Non-Overhaul Repair and Replacement

10-9. Crankshaft Repair

WARNING
Crankshafts may only be repaired by an approved FAA Part
145 Repair Stations. Do not attempt crankshaft repair without
the required FAA certification.
CAUTION: Do not attempt to repair a scored or overheated
crankshaft. Discard and replace scored or scorched crankshafts.

If a crankshaft is repaired by an FAA Repair Station, the nitride
treatment must be restored.
Crankshaft overhaul repairs must be performed by an FAA Part 145 Repair Station
certified to perform crankshaft repair using methods approved by the Federal Aviation
Administration. The repaired crankshaft must meet the dimensional limits specified in the
primary Instructions for Continued Airworthiness.
1. Remove the crankshaft counterweights according to the instructions in Section 10-
9.1.1.
2. Identify the counterweight using the illustrations in Section 10-9.1.2. Inspect the
Counterweight assemblies according to the instructions in Section 10-9.1.3. Replace
Counterweight Bushings according to the instructions in Section 10-9.1.5.
3. Inspect the Hanger Blade Bushings according to the instructions in Section 10-9.1.6.
Replace Hanger Blade Bushings, as required, according to the instructions in
Section 10-9.1.5.
4. Install the Crankshaft Oil Control Plug according to the instructions in Section 10-9.2.
5. After the crankshaft hanger blade bushing replacement, counterweight replacement,
counterweight bushings replacement, or the oil control plug is replaced, perform a
“Magnetic Particle Inspection” on the crankshaft and counterweights and a “Crankshaft
Ultrasonic Inspection” to ensure no cracks developed during the bushing or plug
installation process.
10-9.1. Crankshaft Counterweight Inspection and Repair
This Section is divided in subsections, consisting of multiple tables listing the engine power
train major component part numbers (Table 10-29), parts supersedure (Table 10-33), and
repair instructions for crankshaft counterweights and connecting rods (Table 10-39).
Use Table 10-29 to locate the engine crankshaft part number and subsequent tables in this
section to determine the appropriate counterweight and connecting rod repair instructions.
To determine appropriate piston and piston rings to mate with the connecting rods, refer to
the Tables in Section 10-6.11.

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Table 10-29. Engine Power Train

Crankshaft Connecting Connecting Oil Control

Engine Model Assembly Rod 1 Rod Bearing Bearing Set Collar
A-65 530199A1 A35160A2 639640 627246A2 N/A
530058A6 2 N/A
A-75 530199A1 A35160A2 639640 627246A2 N/A
530058A6 2 N/A
C-75 530196A1 3 A35160A2 639640 530058A4 N/A
530199A1 4 530058A5 N/A
C-85 530196A1 3 A35160A2 639640 530058A4 N/A
530199A1 4 530058A5 N/A
C-90 530182 5 654795 639640 530058A4 N/A
530058A5 N/A
C-145-2 530860 654795 639640 530058A4 N/A
530058A5 N/A
C-145-2H 531113 654795 639649 652152A1 N/A
530058A5 N/A
E-165 352174A2 A36121 530383 646149A1 N/A
E-185-1, 3, 8, 9 537561 A36121 530383 646149A1 N/A
E-185-1, 3, 8, 9 352174 A36121 530383 646149A1 N/A
E-225-4, 8 537561 A36121 530383 646149A1 N/A
627246A2
O-200-A 653012 654795 639640 N/A
530058A6 2
627246A2
O-200-B 653012 654795 639640 N/A
530058A6 2
639640-UPPER 2
O-200-D & X 657466 654795 N/A
657564-LOWER 530058A7
O-240 637069 654794 639640 637062A2 N/A
O-300-A 530860 654795 639640 652152A1 N/A
O-300-B 531113 654795 639640 530516A2 N/A
O-300-C 653382 654795 639640 652152A1 N/A
O-300-D 653382 654795 639640 652152A1 N/A
O-470-2 No Longer Supported
O-470-4 No Longer Supported
O-470-7 No Longer Supported
O-470-11 No Longer Supported
O-470-13A No Longer Supported
O-470-15 No Longer Supported

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Table 10-29. Engine Power Train

Crankshaft Connecting Connecting Oil Control

Engine Model Assembly Rod 1 Rod Bearing Bearing Set Collar
537401A3 6
O-470-A 649141 655910 630826 646589A1 7 N/A
646590A1 8
537401A3 6
O-470-B 653697 655910 630826 N/A
646589A1 7
O-470-C 649141 655910 630826 537401A3 6 N/A
537401A3 6
O-470-E 649141 655910 630826 646589A1 7 N/A
646590A1 8
646591A3 8
646588A1 7
O-470-G 652005 655910 630826
646807A1 9 626739
627795A3 6 10
537401A3 6
O-470-J 649141 655910 630826 646589A1 7 N/A
646590A2 8
537401A3 6
O-470-K 652039 655910 630826 646589A1 7 N/A
646590A2 8
537401A3 6
O-470-L 652039 655910 630826 646589A1 7 N/A
646590A2 8
646807A1 6
O-470-M 652039 655910 630826 646589A1 7 N/A
646590A2 8
537401A3 6
O-470-N 653697 655910 630826 N/A
646589A1 7
646591A3 8
O-470-P 652011 655910 630826 646588A1 7
627795A3 6 9
537401A3 6
O-470-R 649141 655910 630826 646589A1 7 N/A
646590A2 8
646589A1 7
O-470-S 649141 655910 630826 N/A
646590A2 8

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Table 10-29. Engine Power Train

Crankshaft Connecting Connecting Oil Control

Engine Model Assembly Rod 1 Rod Bearing Bearing Set Collar
646589A1 7
O-470-U 649138 655910 630826 N/A
646590A2 8
GO-300-A, C, D, E 627822 654794A1 639640 626943A1 N/A
GTSIO-520-C 653020 655910 630826 633024A2 N/A
GTSIO-520-D 653020 655910 630826 633024A2 N/A
GTSIO-520-H 653020 655910 630826 633024A2 N/A
GTSIO-520-K 653020 655910 630826 633024A2 N/A
GTSIO-520-L 653020 655910 630826 633024A2 N/A
GTSIO-520-M 653020 655910 630826 633024A2 N/A
GTSIO-520-N 653020 655910 630826 633024A2 N/A
IO-240-A 653164 654793A1 642338 637062A3 N/A
IO-240-B 653164 654793A1 642338 637062A3 N/A
IOF-240-B 653164 654793A1 642338 637062A3 N/A
IO-346-A 630778 655910 630826 646594A1 N/A
IO-360-A 653138 654794A1 639640 646595A1 N/A
IO-360-AB 653129 654793A1 642338 646597A1 N/A
IO-360-AF 653129 654793A1 642338 646597A1 N/A
IO-360-C 653138 654794A1 639640 646595A1 N/A
IO-360-CB 653129 654793A1 642338 646597A1 N/A
IO-360-D 653138 654794A1 639640 646595A1 N/A
IO-360-DB 653129 654793A1 642338 646597A1 N/A
IO-360-ES 653129 654793A1 642338 646597A1 N/A
IO-360-G 653139 654794A1 639640 646595A1 N/A
IO-360-GB 653129 654793A1 642338 646597A1 N/A
IO-360-H 653139 654794A1 639640 646595A1 N/A
IO-360-HB 653129 654793A1 642338 646597A1 N/A
IO-360-J 653139 654794A1 639640 646595A1 N/A
IO-360-JB 653129 654793A1 642338 646597A1 N/A
IO-360-K 653139 654794A1 639640 646595A1 N/A
IO-360-KB 653129 654793A1 642338 646597A1 N/A
627795A3 6
IO-470-C 652011 655910 630826 646588A1 7 626739
646591A3 8
627795A3 6
IO-470-D 649133 655910 630826 646588A1 7 626739
646591A3 8

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Table 10-29. Engine Power Train

Crankshaft Connecting Connecting Oil Control

Engine Model Assembly Rod 1 Rod Bearing Bearing Set Collar
627795A3 6
IO-470-E 649133 655910 630826 646588A1 7 626739
646591A3 8
627795A3 6
IO-470-F 649133 655910 630826 646588A1 7 626739
646591A3 8
627795A3 6
IO-470-H 652011 655910 630826 646588A1 7 626739
646591A3 8
627795A3 6
IO-470-J 652009 655910 630826 646588A1 7 626739
646591A3 8
627795A3 6
IO-470-K 652009 655910 630826 646588A1 7 626739
646591A3 8
627795A3 6
IO-470-L 652010 655910 630826 646588A1 7 626739
646591A3 8
627795A3 6
IO-470-M 649133 655910 630826 646588A1 7 626739
646591A3 8
627795A3 6
IO-470-N 652011 655910 630826 646588A1 7 626739
646591A3 8
627795A3 6
IO-470-R 630977 A36121 530383 646588A1 7 626739
646591A3 8
627795A3 6
IO-470-S 649133 655910 630826 646588A1 7 626739
646591A3 8
627795A3 6
IO-470-U 649135 655910 630826 646588A1 7 626739
646591A3 8
627795A3 6
IO-470-V 649135 655910 630826 646588A1 7 626739
646591A3 8

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Table 10-29. Engine Power Train

Crankshaft Connecting Connecting Oil Control

Engine Model Assembly Rod 1 Rod Bearing Bearing Set Collar
646588A1 7
IO-520-A 649134 655910 630826 626739
646591A3 8
IO-520-B 649895 655910 630826 646593A2 629680
IO-520-BA 649896 655910 630826 646593A2 629680
IO-520-BB 649898 655911 642398 646592A2 629680
IO-520-C 649895 655910 630826 646593A2 629680
IO-520-CB 649898 655911 642398 646592A2 629680
646588A1 7
IO-520-D 649134 655910 630826 626739
646591A3 8
646588A1 7
IO-520-E 649134 655910 630826 626739
646591A3 8
646588A1 7
IO-520-F 649134 655910 630826 626739
646591A3 8
646588A1 7
IO-520-J 649134 655910 630826 626739
646591A3 8
646588A1 7
IO-520-K 649134 655910 630826 626739
646591A3 8
646588A1 7
IO-520-L 649134 655910 630826 626739
646591A3 8
IO-520-M 5 649895 655910 630826 646593A2 629680
IO-520-MB 649898 655911 642398 646592A2 629680
IO-520-P 649144-1 655910 630826 646593A2 629739
IO-550-A 649900 655911 642398 646592A2 629680
IO-550-B 649900 655911 642398 646592A2 629680
IO-550-B29B, 33B, 37B 649900 655912 642398 646592A2 629680
IO-550-C 649900 655911 642398 646592A2 629680
IO-550-C25B, 29B, 30B 649900 655912 642398 646592A2 629680
IO-550-D 646623 655911 642398 646592A2 626739
IO-550-E 646623 655911 642398 646592A2 626739
IO-550-F 646623 655911 642398 646592A2 626739
IO-550-G 649900 655911 642398 646592A2 629680
IO-550-L 646623 655911 642398 646592A2 626739
IO-550-N 649900 655911 642398 646592A2 629680
IO-550-P 649900 655911 642398 646592A2 629680
IO-550-R 649900 655911 642398 646592A2 629680
IOF-550-B, C 649900 655911 642398 646592A2 629680

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 Non-Overhaul Repair and Replacement
Table 10-29. Engine Power Train

Crankshaft Connecting Connecting Oil Control

Engine Model Assembly Rod 1 Rod Bearing Bearing Set Collar
IOF-550-D, E, F, L 646623 655911 642398 646592A2 626739
IOF-550-N, P, R 649900 655911 642398 646592A2 629680
LTSIO-360-E 653137 654794 639640 646596A1 N/A
LTSIO-360-EB 653136 654793 642338 646597A1 N/A
LTSIO-360-KB 653136 654793 642338 646597A1 N/A
LTSIO-360-RB 653136 654793 642338 646597A1 N/A
LTSIO-520-AE 649144-2 655000 630826 646591A4 626739
TSIO-360-A 653138 654794 639640 646595A1 N/A
TSIO-360-AB 653129 654793 642338 646597A1 N/A
TSIO-360-B 653138 654794 639640 646595A1 N/A
TSIO-360-C 653139 654794 639640 646595A1 N/A
TSIO-360-CB 653129 654793 642338 646597A1 N/A
TSIO-360-D 653139 654794 639640 646595A1 N/A
TSIO-360-DB 653129 654793 642338 646597A1 N/A
TSIO-360-E 653139 654794 639640 646595A1 N/A
TSIO-360-EB 653129 654793 642338 646597A1 N/A
TSIO-360-F 653139 654794 639640 646595A1 N/A
TSIO-360-FB 653129 654793 642338 646597A1 N/A
TSIO-360-G 653139 654794A1 639640 646595A1 N/A
TSIO-360-GB 653129 654793 642338 646597A1 N/A
TSIO-360-H 653139 654794 639640 646595A1 N/A
TSIO-360-HB 653129 654793 642338 646597A1 N/A
TSIO-360-JB 653129 654793 642338 646597A1 N/A
TSIO-360-KB 653129 654793 642338 646597A1 N/A
TSIO-360-MB 653129 654793 642338 646597A1 N/A
TSIO-360-RB 653129 654793 642338 646597A1 N/A
TSIO-360-SB 653129 654793 642338 646597A1 N/A
627795A3 6
TSIO-470-B 652011 646437A2 630826 626739
646588A1 7
627795A3 6
TSIO-470-C 652011 646437A2 630826 626739
646588A1 7
627795A3 6
TSIO-470-D 652011 646437A2 630826 626739
646588A1 7
TSIO-520-AE 649144-1 655000 630826 646591A4 626739
TSIO-520-AF 649134 655004 630826 646591A3 8 626739
TSIO-520-B 649895 655004 630826 646593A2 629680

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Table 10-29. Engine Power Train

Crankshaft Connecting Connecting Oil Control

Engine Model Assembly Rod 1 Rod Bearing Bearing Set Collar
TSIO-520-BB 649898 655005 642398 646592A2 629680
TSIO-520-BE 649898 655005 642398 646592A2 629680
646588A1 7
TSIO-520-C 649134 655004 630826 626739
646591A3 8
TSIO-520-CE 649148 655911 642398 646592A2 626739
TSIO-520-D 649895 655004 630826 646593A2 629680
TSIO-520-E 649895 655004 630826 646593A2 629680
TSIO-520-EB 649898 655005 642398 646592A2 629680
646588A1 7
TSIO-520-H 649134 655004 630826 626739
646591A3 8
TSIO-520-J 649895 655004 630826 646593A2 629680
TSIO-520-JB 649898 655005 642398 646592A2 629680
TSIO-520-K 649895 655004 630826 646593A2 629680
TSIO-520-KB 649898 655005 642398 646592A2 629680
TSIO-520-L 649895 655004 630826 646593A2 629680
TSIO-520-LB 649898 655005 642398 646592A2 629680
646588A1 7
TSIO-520-M 649134 655004 630826 626739
646591A3 8
TSIO-520-N 649895 655004 630826 646593A2 629680
TSIO-520-NB 649898 655005 642398 646592A2 629680
646588A1 7
TSIO-520-P 649134 655004 630826 626739
646591A3 8
646588A1 7
TSIO-520-R 649134 655004 630826 626739
646591A3 8
646588A1 7
TSIO-520-T 649134 655004 630826 626739
646591A3 8
TSIO-520-UB 649898 655005 642398 646592A2 629680
TSIO-520-VB 649898 655005 642398 646592A2 629680
TSIO-520-WB 649898 655005 642398 646592A2 629680
TSIO-550-A 649900 655911 642398 646592A2 629680
TSIO-550-B 649900 655911 642398 646592A2 629680
TSIO-550-C 649900 655911 642398 646592A2 629680
TSIO-550-G 649900 655911 642398 646592A2 629680
TSIO-550-J 649900 655911 642398 646592A2 629680
TSIO-550-K 649900 655911 642398 646592A2 629680
TSIO-550-N 649900 655911 642398 646592A2 629680

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 Non-Overhaul Repair and Replacement
Table 10-29. Engine Power Train

Crankshaft Connecting Connecting Oil Control

Engine Model Assembly Rod 1 Rod Bearing Bearing Set Collar
TSIOF-550-D 649900 655911 642398 646592A2 629680
TSIOF-550-J 649900 655911 642398 646592A2 629680
TSIOF-550-K 649900 655911 642398 646592A2 629680
TSIOL-550-A 652359 655911 642398 646592A2 629680
TSIOL-550-B 652359 655911 642398 646592A2 629680
TSIOL-550-C 652359 655911 642398 646592A2 629680
1. See Table 10-39 for new and old connecting rod part numbers and associate hardware usage
2. With 633141 thrust washer
3. Tapered crankshaft with removable prop flange
4. Propeller flange included with crankshaft forging
5. Non-production engine
6. Flange type bearing for use with Phase 1 style crankcase and crankshaft. See Service Bulletin M78-9 or latest revision.
7. Thrust washer type bearings for use with Phase 2 style crankcase and crankshaft. See Service Bulletin M78-9 or latest revision.
8. For use with Phase 3 style crankcase and crankshaft. See Service Bulletin M78-9 or latest revision.
9. For O-470-G engines with modernized crankshafts using oil transfer collar.
10. For O-470-G engines with modified crankshafts. Remove and discard nylon wipers for O-470-G

Table 10-30. Crankshaft Assembly Part Number History

Crankshaft
Specification Assembly Supersedes Supersedes Supersedes Supersedes
O-200-A 653012 531434
O-200-B 653012 531434
O-200-D & X 657466
O-300-A 530860
O-300-C 653382 1 652110 628124
O-300-D 653382 2 652110 628124
O-470-A 649141 633225 537290
O-470-B 653697 633227 539576
O-470-C 649141 633225 537290
O-470-E 649141 633225 537290
O-470-F 649141 633225 537290
O-470-G 652005 633256
O-470-J 649141 633225 537290
O-470-K 652039 633219 539665
O-470-L 652039 633219 539665
O-470-M 652039 633219 539665
O-470-N 653697 633227 539576
O-470-R 649141 633225 537290
O-470-S 649141 633225 537290
O-470-U 649138 643911 641905

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Table 10-30. Crankshaft Assembly Part Number History
Crankshaft
Specification Assembly Supersedes Supersedes Supersedes Supersedes
GO-300-A, C, D, E 627822
GIO-550-A3 652800A1
GTSIO-520-C 653020 652832 652821 652001 635104
GTSIO-520-D 653020 652832 652821 652001 635104
GTSIO-520-H 653020 652832 652821 652001 635104
GTSIO-520-K 653020 652832 652821 652001 635104
GTSIO-520-L 653020 652832 652821 652001 635104
GTSIO-520-M 653020 652832 652821 652001 635104
GTSIO-520-N 653020 652832 652821 652001 635104
IO-240-A 653164
IO-240-B 653164
IOF-240-B 653164
IO-346-A 630778
IO-360-A 653138 652047 649785 639200 634479
IO-360-AB 653129 652014 643627 642350
IO-360-AF 653129
IO-360-C 653138 652047 649785 639200 634479
IO-360-CB 653129 652014 643627 642350
IO-360-D 653138 652047 649785 639200 634479
IO-360-DB 653129 652014 643627 642350
IO-360-ES 653129
IO-360-G 653139 652048 639786
IO-360-GB 653129 652014 643627 642350
IO-360-H 653139 652048 639786
IO-360-HB 653129 652014 643627 642350
IO-360-J 653139 652048 639786
IO-360-JB 653129 652014 643627 642350
IO-360-K 653139 652048 639786
IO-360-KB 653129 652014 643627 642350
IO-470-C 652011 652006 633256 626784
IO-470-D 649133 630927 627530
IO-470-E 649133 630927 627530
IO-470-F 649133 630927 627530
IO-470-G 649133 630927 627530
IO-470-H 652011 652008 628995 630977 627348
IO-470-J 652009 643089 633246 628358
IO-470-K 652009 643089 633246 628358
IO-470-L 652010 643090 630886 628694

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Table 10-30. Crankshaft Assembly Part Number History
Crankshaft
Specification Assembly Supersedes Supersedes Supersedes Supersedes
IO-470-M 649133 630927 627530
IO-470-N 652011 652006 643091 630932 629309
IO-470-P 629882
IO-470-R 630977 629366
IO-470-S 649133 630927 627530
IO-470-U 649135 632195
IO-470-V 649135 632195
IO-520-A 649134 631716
IO-520-B 649895 633620
IO-520-BA 649896 639243
IO-520-BB 649898 646438 642396
IO-520-C 649895 633620
IO-520-CB 649898 646438 642396
IO-520-D 649134 631716
IO-520-E 649134 631716
IO-520-F 649134 631716
IO-520-J 649134 631716
IO-520-K 649134 631716
IO-520-L 649134 631716
IO-520-M 649895 633620
IO-520-MB 649898 646438 642396
IO-520-P 649144-1
IO-550-A 649900 646604
IO-550-B 649900 646604
IO-550-C 649900 646604
IO-550-D 646623
IO-550-E 646623
IO-550-F 646623
IO-550-G 649900
IO-550-L 646623
IO-550-N 649900
IO-550-P 649900
IO-550-R 649900
IOF-550-N 649900
IOF-550-P 649900
IOF-550-R 649900
LTSIO-360-E 653137 652045 641382
LTSIO-360-EB 653136 652015 643633
LTSIO-360-KB 653136 652015 643633

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Table 10-30. Crankshaft Assembly Part Number History
Crankshaft
Specification Assembly Supersedes Supersedes Supersedes Supersedes
LTSIO-360-RB 653136
LTSIO-520-AE 649144-2 643126-1
TSIO-360-A 653138 652047 649785 639200 634479
TSIO-360-AB 653129 652014 643627 642350
TSIO-360-B 653138 652047 649785 639200 634479
TSIO-360-C 653139 652048 639786
TSIO-360-CB 653129 652014 643627 642350
TSIO-360-D 653139 652048 639786
TSIO-360-DB 653129 652014 643627 642350
TSIO-360-E 653139 652048 639786
TSIO-360-EB 653129 652015 643633 642376
TSIO-360-F 653139 652048 639786
TSIO-360-FB 653129 652014 643627 642350
TSIO-360-G 653139 652048 639786
TSIO-360-GB 653129 652014 643627 642350
TSIO-360-H 653139 652048 639786
TSIO-360-HB 653129 652014 643627 642350
TSIO-360-JB 653129 652014 643627 642350
TSIO-360-KB 653129 652015 643633 642376
TSIO-360-LB 653129 652014 643627 642350
TSIO-360-MB 653129 652014 643627
TSIO-360-RB 653129
TSIO-360-SB 653129
TSIO-470-B 652011 652008 628995
TSIO-470-C 652011 652008 628995
TSIO-470-D 652348 652007 632494
TSIO-520-AE 649144-1 643126
TSIO-520-AF 649134 631716
TSIO-520-B 649895 633620
TSIO-520-BB 649898 646438 642396
TSIO-520-BE 649898 646438 642396
TSIO-520-C 649134 631716
TSIO-520-CE 649148 646683
TSIO-520-D 649895 633620
TSIO-520-E 649895 633620
TSIO-520-EB 649898 646438 642396
TSIO-520-G 649134 631716
TSIO-520-H 649134 631716
TSIO-520-J 649895 633620

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Table 10-30. Crankshaft Assembly Part Number History
Crankshaft
Specification Assembly Supersedes Supersedes Supersedes Supersedes
TSIO-520-J 649895 633620
TSIO-520-T 649134 631716
TSIO-520-UB 649898 646438 642396
TSIO-520-VB 649898 646438 642396
TSIO-520-WB 649898 646438 642396
TSIO-550-A 649900
TSIO-550-B 649900
TSIO-550-C 649900
TSIO-550-E 649900
TSIO-550-G 649900
TSIO-550-J 649900
TSIO-550-K 649900
TSIO-550-N 649900
TSIOF-550-D 649900
TSIOF-550-J 649900
TSIOF-550-K 649900
TSIOL-550-A 652359
TSIOL-550-B 652359
TSIOL-550-C 652359
1. Part No. 653382 Crankshaft, Part No. 656081 Gear and four each Part No. 654584 bolts must be used together
2. Part No. 653382 Crankshaft, Part No. 630690 Gear and four each Part No. 654584 bolts must be used together
3. Not a production engine

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Non-Overhaul Repair and Replacement
Table 10-31. Crankshaft Assemblies
Hanger
Blade
Bushing BUSH CWT CWT BUSH Cheek PIN CWT. RET RET
C/S Assy 1 I.D. Qty C/S CWT Bushing I.D. LOC. CWT. PIN DIA. ORDER Plate RING
531015 .4613 1 531017 531016 .4613 2
5
.4643 .4643 2 .3758
530860 630261-15 .3768
530868 402805-3
530863 .435 1 530864 530866 .435 2 6
.438 .438
531015 .4613 1 531017 531016 .4613 2
5
.4643 .4643 .3758
531113 630261-15 2 .3768 530868 402805-3
530863 .435 1 530864 530866 .435 2 6
.438 .438
2 2 3
.732 .732 .491
627822 626566 .739
2 627821 626564 .739
5 632261-11 2 .492
3 633976 629004
2 8 3
531015 .4613 1 531017 531016 .4613 2 5
.4643 .4643 .3758
628124 630261-15 2 .3768
530868 402805-3
530863 .435 1 530864 530866 .435 2 6
.438 .438
2 639195 2 643626-105 .565 6
.566

646623 350998
.622 1 639196 639193
.622 5 643626-103 .474 4 643629 629104
.626 .626 .475
1 639196 5 643626-104 .527 5
.528
.622 2 .622 2 .556 6
649133 350998 .626
639195 639193 .626
643626-101 .557 643629 629104
2 5 6
2 639195 2 643626-101 .556 6
.557

649134 350998
.622 1 639196 639193
622 5 643626-103 .474 4 643629 629104
.626 .626 .475
1 639196 5 643626-104 .527 5
.528
2 639195 2 643626-101 .556 6
.557

639135 350998
.622 1 639196 639193
622 5 643626-104 .527 5 643629 629104
.626 .626 .528
1 639196 5 643626-106 .507 4.5
.508
2 639195 2 643626-101 .556 6
.557

649138 350998
.622 1 639195 639193
622 5 643626-104 .527 5 643629 629104
.626 .626 .528
1 639195 5 643626-106 .507 4.5
.508
1 2 643626-101
.556 6
.622 .622 .557
649141 350998 .626
639195 639193 .626
643629 629104
1 2 643626-104 .527 5
.528

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Table 10-31. Crankshaft Assemblies
Hanger
Blade
Bushing BUSH CWT CWT BUSH Cheek PIN CWT. RET RET
1
C/S Assy I.D. Qty C/S CWT Bushing I.D. LOC. CWT. PIN DIA. ORDER Plate RING
1 2 643626-104
.527 5
.622 .622 .528
649144-1 350998 .626
639195 639193 .626
643629 629104
1 2 643626-105 .565 6
.566
1 2 643626-104
.527 5
.622 .622 .528
649144-2 350998 .626
639195 639193 .626
643629 629104
1 2 643626-105 .565 6
.566
2 639195 2 643626-105 .565 6
.566

639148 350998
.622 1 639196 639193
.622 5 643626-103 .474 4 643629 629104
.626 .626 .475
1 639196 5 643626-104 .527 5
.528
2 639195 2 643626-101 .556 6
.557

649895 350998
.622 1 639196 639193
.622 5 643626-103 .474 4 643629 629104
.626 .626 .475
1 639196 5 643626-104 .527 5
.528
2 639195 2 643626-101 .556 6
.557

649896 350998
.622 1 639196 639193
.622 5 643626-101 .556 6 643629 629104
.626 .626 .557
1 639196 5 643626-103 .474 4
.475
2 639195 2 643626-105 .565 6
.566

649898 350998
.622 1 639196 639193
.622 5 643626-103 .474 4 643629 629104
.626 .626 .475
1 639196 5 643626-104 .527 5
.528
2 639195 2 643626-105 .565 6
.566

649900 350998
.622 1 639196 639193
.622 5 643626-103 .474 4 643629 629104
.626 .626 .475
1 639196 5 643626-104 .527 5
.528
1 639197 2 643626-105 .565 6
.622 .622 .566
652005 350998 .626
639193 .626
643629 629104
1 639197 2 643626-108 .594 4
.595
1 639195 2 643626-101 .556 6
.622 .622 .557
652009 350998 .626
639193 .626
643629 629104
1 639195 2 643626-104 .527 5
.528

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Table 10-31. Crankshaft Assemblies
Hanger
Blade
Bushing BUSH CWT CWT BUSH Cheek PIN CWT. RET RET
1
C/S Assy I.D. Qty C/S CWT Bushing I.D. LOC. CWT. PIN DIA. ORDER Plate RING
2 639195 2 643626-101 .556 6
.622 .622 .557
652010 350998 .626
639193 .626
643629 629104
2 639195 5 643626-104 .527 5
.528
2 639195 2 643626-101 .556 6
.622 .622 .557
652011 350998 .626
639193 .626
643629 629104
2 639195 5 643626-101 .556 6
.557
2 639195 2 643626-101 .556 6
.622 .622 .557
652039 350998 .626
639193 .626
643629 629104
2 639195 5 643626-101 .556 6
.557
2 639195 2 643626-101 .565 6
.566

652348 350998
.622 1 639196 639193
.622 5 643626-103 .474 4 643629 629104
.626 .626 .475
1 639196 5 643626-104 .527 5
.528
2 639195 2 643626-105 .565 6
.566

652359 350998
.622 1 639196 639193
.622 5 643626-103 .474 4 643629 629104
.626 .626 .475
1 639196 5 643626-106 .507 4.5
.508
2 2 643626-104 .527 3
.528

653020 658975
.754 2 652833 628978
.754 5 643626-104 .527 3 631808 629004
.757 .757 .528
2 8 643626-104 .527 3
.528
1 639199 2 643626-110 .498 4.5
.604 .604 .499
653129 639580 .607
639198 .607
653143 629004
1 639199 2 643626-111 .552 6
.553
1 639199 2 643626-110 .498 4.5
.604 .604 .499
653136 639580 .607
639198 .607
653143 629004
1 639199 2 643626-111 .552 6
.553
1 639199 2 643626-110 .498 4.5
.604 .604 .499
653137 639580 .607
639198 .607
653143 629004
1 639199 2 643626-111 .552 6
.553
1 639199 2 643626-109 .545 6
.604 .604 .546
653138 639580 .607
639198 .607
653143 629004
1 639199 2 643626-109 .545 6
.546

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Table 10-31. Crankshaft Assemblies
Hanger
Blade
Bushing BUSH CWT CWT BUSH Cheek PIN CWT. RET RET
1
C/S Assy I.D. Qty C/S CWT Bushing I.D. LOC. CWT. PIN DIA. ORDER Plate RING
1 639199 2 643626-110 .498 4.5
.604 .604 .499
653139 639580 .607
639198 .607
653143 629004
1 639199 2 643626-111 .552 6
.553
1 639199 2 643626-112 .520 5
.604 .604 .521
653382 639580 .607
639198 .607
653143 629004
1 639199 2 643626-112 .520 5
.521
2 639195 2 643626-105 .565 6
.622 .622 .566
653697 350998 .626
639193 .626
643629 629104
2 639195 5 643626-105 .565 6
.566
2 2 643626-104 .527 3
.528
652800A1 .754 2 .754 5 643626-104 .527 3
3 628975 .757
652833 628978 .757 .528
631808 629004
2 8 643626-104 .527 3
.528
1 639195 2 643626-105 .565 6
654359 .622 .622 .566
3
350998 .626
639193 .626
643629 629104
1 639195 2 643626-105 .565 6
.566

1. Replacement Crankshaft hanger blade bushings may be purchased in standard and oversize dimensions as listed in Table 10-32
2. If replacing Part No. 630261 pin with Part No. 643626 pin, the Part No. 643629 plate must be used
3. Used in non-production engines only

Table 10-32. Crankshaft Hanger Blade Bushing Sizes

Crankshaft Blade
Bushing Part No. STANDARD P 0.0015 P 0.003 P 0.005 P 0.010 P 0.015
350998 AVAILABLE AVAILABLE AVAILABLE AVAILABLE AVAILABLE AVAILABLE
530863 AVAILABLE N/A AVAILABLE AVAILABLE N/A N/A
531015 AVAILABLE N/A N/A N/A N/A N/A
537038 AVAILABLE N/A N/A N/A N/A N/A
626566 AVAILABLE N/A N/A AVAILABLE N/A N/A
628975 AVAILABLE N/A AVAILABLE AVAILABLE AVAILABLE N/A
639580 AVAILABLE AVAILABLE AVAILABLE AVAILABLE AVAILABLE AVAILABLE

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Table 10-33. Wide Rod Crankshaft
(NOT CURRENT PRODUCTION)

Hanger CWT RET RET

Blade BUSH CWT C/S CWT Bushing BUSH Cheek CWT. PIN PIN CWT. PLATE RING
1 2 3 4 5
C/S Assy Bushing I.D. Qty I.D. LOC. DIA. ORDER
352174 .622 .622 .5554
(E-185-1, 3, 350996 .626
2 352117 350977 .626
2 630261-4 .5574
6 352115 352116
8, 9, 11)
537661 350998
.622
1 352117 350997
.622
2 630261-4
.5554
6 352115 352116
(E-185-1, 3, .626 .626 .5574
8, 9, 11 & .6534 .6534 .5554
E-225-4, 8) 537038 .6554
1 537049 537044 .6554
2 630261-4 .5574
5 352115 352116
537290 350998
.622
1 352117 350997
.622
2 630261-4
.5554
6 352115 352116
(O-470-A, .626 .626 .5574
C, E, F, J & .6534 .6534 .5554
R) 537038 .6554
1 537049 537044 .6554
2 630261-4 .5574
5 352115 352116
.622 .622 .5652
539576 350998 .626
1 352117 350997 .626
2 630261-2 .5662
6 352115 352116
(O-470-B &
.6534 .6534 .5947
N) 537038 .6554
1 537049 537044 .6554
2 630261-1 .5967
6 352115 352116
.622 .622 .5931
350998 .626
1 352117 350997 .626
2 630261-5 .5951
9 352115 352116
627576
(O-470-G) .6534 .6483 .5931
537038 .6554
1 625818 625817 .6523
2 630261-5 .5951
6 352115 352116
.622 .622 .5554
539665 350998 .626
2 352117 350997 .626
2 630261-4 .5574
6 352115 352116
(O-470-K,
.622 .622 .5554
L, M) 350998 .626
2 352117 350997 .626
5 630261-4 .5574
6 352115 352116
.622 .622 .5554
350998 .626
2 352117 350997 .626
2 630261-4 .5574
6 352115 352116
627587
(O-470-P) .622 .622 .5554
350998 .626
2 352117 350997 .626
5 630261-4 .5574
6 352115 352116
.622 .622 .5554
350998 .626
2 352117 350997 .626
2 630261-4 .5574
6 352115 352116
626784
(IO-470-C) .622 .622 .5554
350998 .626
2 352117 350997 .626
5 630261-4 .5574
6 352115 352116

627530 .622 .622 .5554

350998 .626
2 352117 350997 .626
2 630261-4 .5574
6 352115 352116
(IO-470-D,
E, F, G, M & .622 .622 .5554
S) 350998 .626
2 352117 350997 .626
5 630261-4 .5574
6 352115 352116
.622 .622 .5554
350998 .626
2 352117 350997 .626
2 630261-4 .5574
6 352115 352116
627348
(IO-470-H) .622 .622 .5554
350998 .626
2 352117 350997 .626
5 630261-4 .5574
6 352115 352116
.622 .622 .5554
350998 .626
2 352117 350997 .626
2 630261-4 .5574
6 352115 352116
629366
(IO-470-R) .622 .622 .5554
350998 .626
2 352117 350997 .626
5 630261-4 .5574
6 352115 352116

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Table 10-33. Wide Rod Crankshaft
(NOT CURRENT PRODUCTION)
Hanger CWT RET RET
Blade BUSH CWT C/S CWT Bushing BUSH Cheek CWT. PIN PIN CWT. PLATE RING
1 2 3 4 5
C/S Assy Bushing I.D. Qty I.D. LOC. DIA. ORDER
.622 .622 .5554
629882 350998 .626
1 352117 350997 .626
2 630261-2 .5574
6 352115 352116
(IO-470-P,
.622 .622 .5554
T) 350998 .626
1 352117 350997 .626
2 630261-2 .5574
6 352115 352116
.622 .622 .5554
628358 350998 .626
1 352117 350997 .626
2 630261-4 .5574
6 352115 352116
(IO-470-J,
.6534 .6534 .5554
K) 537038 .6554
1 537049 537044 .6554
2 630261-4 .5574
5 352115 352116
.622 .622 .5554
350998 .626
2 352117 350997 .626
2 630261-4 .5574
6 352115 352116
628694
(IO-470-L) .6534 .6534 .527
350998 .6554
2 352117 350997 .6554
5 630261-3 .528
5 352115 352116
.622 .622 .5554
350998 .626
2 352117 350997 .626
2 630261-4 .5574
6 352115 352116
629309
(IO-470-N) .6534 .6534 .5554
350998 .6554
2 352117 350997 .6554
5 630261-4 .5574
6 352115 352116
632195 350998
.622
2 352117 350997
.622
2 630261-4
.622 6
(IO-470-U .626 .626 .626
& V) .622 .622 .622 5
350998 .626
1 631968 350997 .626
5 630261-3 .626
352115 352116

350998
.622
1 631968 350997
.622
5 630261-32
.622 4.5
.626 .626 .626

1. Counterweight Part No. 352117 superseded by Part No. 639195;

Counterweight Part No. 537049 superseded by Part No. 639205; 
Counterweight Part No. 639205 superseded by Part No. 639205A1;
Counterweight Part No. 625818 superseded by Part No. 639210; 
Counterweight Part No. 639210 superseded by Part No. 639210A1
2. Bushing Part No. 350997 superseded by Part No. 639193;
Bushing Part No. 537044 superseded by Part No. 639204
3. Counterweight Supersedure (See Table 10-34 for details): 
When using Part No. 630261-x pins, Part No. 635623 retainer plates must be used
When using Part No. 643626-x pins, Part No. 643629 retainer plates must be used
4. Plate Part No. 352115 superseded by Part No. 629105; 
Plate Part No. 629105 superseded by Part No. 635623; 
Plate Part No. 635623 superseded by Part No. 643629
5. Retaining Ring Part No. 352116 superseded by Part No. 629104

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Non-Overhaul Repair and Replacement

Table 10-34. Counterweight Supersedure

Superseded Part
Current Part No. Pin Diameter No. Pin Diameter Original Part No. Pin Diameter
643626-101 0.556 - 0.557 630261-35 0.5559 - 0.5569 630261-4 0.554 - 0.5574
643626-103 0.474 - 0.475 630261-38 0.474 - 0.475 630261-27 0.474 - 0.475
643626-104 0.527 - 0.528 630261-37 0.527 - 0.528 630261-3 0.527 - 0.528
643626-105 0.565 - 0.566 630261-40 0.5652 - 0.5662 630261-2 0.5652 - 0.5662
643626-106 0.507 - 0.508 630261-39 0.507 - 0.508 630261-32 0.507 - 0.508
643626-107 0.490 - 0.491 630261-34 0.4902 - 0.4906 N/A N/A
643626-108 0.594 - 0.595 630261-36 0.5931 - 0.5951 630261-5 0.5931 - 0.5951
643626-109 0.545 - 0.546 630261-41 0.545 - 0.546 N/A N/A
643626-110 0.498 - 0.499 630261-43 0.498 - 0.499 N/A N/A
643626-111 0.552 - 0.553 630261-44 0.552 - 0.553 N/A N/A
643626-112 0.520 - 0.521 N/A N/A N/A N/A
N/A N/A N/A N/A 630261-11 0.4916 - 0.4921
N/A N/A N/A N/A 630261-15 0.3758 - 0.3768
N/A N/A N/A N/A 630261-17 0.6700 - 0.6710

10-9.1.1. Crankshaft Counterweight Removal

1. Remove the counterweight retaining rings (snap rings) from the counterweight bores
using Inside snap ring pliers with a 90 degree bend.
2. Remove the counterweight pin retaining plates from the bores. The plates are a close
tolerance fit and may require slight rocking to remove them.
3. Remove the counterweight pins with a magnet.
CAUTION: Retaining rings are single use; discard immediately
upon removal.
4. Discard the retaining plates and retaining rings.

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10-9.1.2. Counterweight Identification
Counterweights dimensions are illustrated in Figure 10-25 through Figure 10-33.

Figure 10-25. Part No. 530864 Counterweight Assembly

(made with 530865 Counterweight and 530866 Bushings)

Figure 10-26. Part No. 531017 Counterweight Assembly

(made with 530865 Counterweight and 531016 Bushings)

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Non-Overhaul Repair and Replacement

Figure 10-27. Part No. 639196 Counterweight Assembly

(made with 631903 Counterweight and 639193 Bushings)

Figure 10-28. Part No. 639197 Counterweight Assembly

(made with 633339 Counterweight and 639193 Bushings)

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Figure 10-29. Part No. 639195 Counterweight Assembly

(made with 351000 Counterweight and 639193 Bushings)

Figure 10-30. Part No. 639199 Counterweight Assembly

(made with 629693 Counterweight and 639198 Bushings)

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Figure 10-31. Part No. 652833 Counterweight Assembly

(made with 652834 Counterweight and 628978 Bushings)

Figure 10-32. Part No. 627821 Counterweight Assembly

(made with 626688 Counterweight and 626564 Bushings)

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Figure 10-33. Part No. 639205 and 639210 Counterweight Assemblies

(made with 35100 Counterweight)
(639205 Counterweight uses 639204 Bushings)
(639210 Counterweight uses 639209 Bushings)

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10-9.1.3. Crankshaft Counterweight Inspection
CAUTION: Only the case hardened (tuftrided) counterweight
assemblies P/N 639195, 639196, 639197, 639199, 639205, or later
design and 627821, 530864, 531017 (non-tuftrided) counterweight
assemblies may be considered for bushing replacement. Discard all
other earlier design counterweights.
CAUTION: On GTSIO-520 engine models, ALL Part No. 631810
counterweights must be replaced with 652833, or later design
counterweights. Scrap all 631810 counterweights upon removal.
Equipment required
• 4% copper sulfate (CuSO4) and water solution (by volume)
• Borroughs Part No. 8077C, Counterweight Bushing Removal/Installation Fixture
(Section 2-1), or equivalent
• Two matched V-blocks
1. Inspect the crankshaft counterweight bump surface as shown in Figure 10-34; bump
surface contact marks must not exceed 0.005 inches in depth.
2. Remove and discard the counterweight bushings using the Counterweight Bushing
Removal/Installation Fixture 8077C or equivalent.
3. Thoroughly clean the counterweight bushing bore.
4. Verify tuftriding is present on the counterweight assemblies by placing one drop of a
4% copper sulfate (CuSO4) and water solution (by volume) on the cleaned surface of
the counterweight bushing bore.
5. Allow at least 15 seconds for the chemical reaction to take place.
6. Formation of red deposits indicates the absence of tuftriding. Discard any
counterweight that does not exhibit tuftriding and replace with new counterweights.
7. If no reaction occurs, wipe off copper sulfate and water solution. The counterweight
may be reused during overhaul, provided it meets all other inspection criteria.
8. Perform a “Magnetic Particle Inspection” on the crankshaft and counterweights
according to the instructions in Section 11-3.

INSPECT THIS
BUMP SURFACE AREA

Figure 10-34. Crankshaft Counterweight Bump Service Inspection

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10-9.1.4. Crankshaft Counterweight Bushing Bore Inspection
Equipment required
• Federal Dimension Air Gauge (with appropriate setting ring and air plug) or
• Starrett No. 78 series 3-point contact inside micrometer (Section 2-1)
1. Verify the counterweight bushing bores are smooth. Discard counterweights with worn,
pitted, fretted or out-of-round bushing bores.
2. Use a Federal Dimension Air Gauge (with appropriate setting ring and air plug) or
Starrett No. 78 series 3-point contact inside micrometer to measure the bushing bores.
Compare the bushing bores specified total indicator reading (T.I.R.) to the
specifications in Table 10-35. Discard counterweights with bushing bores exceeding
the specified dimensions.
3. Carefully inspect the counterweight counterbores for signs of wear in the wall that
retains the counterweight pin retaining plates. This area is adjacent to the inside edge of
the retaining ring groove. It may appear as an additional step and/or taper of the hole
into the retaining ring groove. Discard any counterweight that is:
a. Cracked
b. Worn, pitted, fretted, or out of round bushing bores
c. Worn or has distortions in the retaining ring groove that can affect the retaining
ring seating
4. If no plate wear is evident, check the retaining ring groove in each hole for wear
patterns that can affect the retaining ring seating. Any worn condition that may affect
retaining ring seating will require replacement of the counterweight.
5. Crankshaft counterweights are matched in pairs with a maximum weight variation of
two grams. If either counterweight is damaged, replace the counterweights as a
matched pair.

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Figure 10-35. Counterweight Bushing Bore Inspection

Table 10-35. Counterweight Bushing Bore Dimensions

“A” Diameter
Counterweight Assembly Part No. Counterweight Part No. See Figure 10-35
530864 530865 0.687 - 0.688
531017 530865 0.687 - 0.688
627821 626688 1.000 - 1.001
639195
639205 351000 0.8745 - 0.8755
639210
639196 631903 0.8745 - 0.8755
639197 633339 0.8745 - 0.8755
639199 629693 1.000 - 1.001
652833 652834 1.000 - 1.001

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10-9.1.5. Crankshaft Counterweight Bushing Replacement
Replace all crankshaft counterweight bushings at overhaul:
Equipment Required
• Borroughs Part No. 8077C Counterweight Bushing Removal/Installation Fixture, or
equivalent
• Federal Dimension Air Gauge (with appropriate setting ring and air plug) or
• Starrett No. 78 series 3 point contact inside micrometers
• Snap ring pliers (with 90-degree bend)
• Arbor press
The complete crankshaft /counterweight assembly is dynamically balanced and the
counterweights are matched in pairs with a maximum weight variation of two grams. If
either counterweight is damaged, both counterweights in the matched pair must be
replaced as a pair on that crankshaft cheek, even if only one counterweight is
unserviceable.
WARNING
Removing the counterweight bushings with makeshift tools
may cause irreparable damage which could lead to engine
malfunction.
1. Remove the crankshaft counterweight bushings with a Borroughs Part No. 8077C
Counterweight Bushing Removal/Installation Fixture and an arbor press.
2. Measure the crankshaft counterweight bushing bore inside diameter. Bushing bores
must be smooth and cylindrical (no out of round). Replacement bushings require an
interference fit of 0.0015 to 0.003 inches in the bushing bores.
3. Visually inspect the counterweights to determine acceptability of parts. Replace
counterweights with worn, pitted, fretted or out-of-round bushing bores.
WARNING
Counterweight bushings and bushing retainer plates (except as
indicated in Figure 10-37) require an interference fit. Replace
counterweight bushings (or counterweights) if insertion in the
bushing bore is possible without resistance.
4. Inspect counterweight bores/counterbores for signs of wear in the wall that retains the
counterweight pin retaining plates (area adjacent to the inside edge of the retaining
groove; it may appear as a taper of the hole into the retaining ring groove). If any wear
is evident, discard and replace the counterweight.
NOTE: Replace both counterweights in the matched pair even if only one
counterweight is unacceptable.
5. If the counterweight conforms to specification, check the counterweight retaining ring
groove for distortions in width, roundness or pattern which can affect the seating of the
retaining ring. Discard and replace the counterweight matched pair if wear or
distortions are found even on one counterweight.

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6. Install new bushings in the same positions as the old bushings on the counterweight
assemblies (Figure 10-36) using the Borroughs Part No. 8077C Counterweight
Bushing Removal/Installation Fixture. The bushing lead-in (Figure 10-36) must be
positioned toward the counterweight during installation. Press the bushing flush with
the surfaces as illustrated.

Figure 10-36. Counterweight Inspection, Repair and Installation

Applicable to 360, 470, IO520, LTSIO-520, and 550 Series Engines
Not Applicable to GTSIO-520 (See Figure 10-37)
7. Verify newly installed bushing dimensions in Table 10-36. Close tolerances require
replacement bushings shall be 100% dimensionally inspected using calibrated, accurate
measuring equipment (one of the following):
a. Federal Dimension Air Gauge (with appropriate setting ring and air plug)
b. Starrett No. 78 series 3 point contact inside micrometers.

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8. Perform a “Magnetic Particle Inspection” according to the instructions in Section 11-3
on the crankshaft counterweight assembly to ensure the counterweight is free of cracks.

Table 10-36. Counterweight Bushing Bore Dimensions

“A” Diameter
Counterweight Assembly Part No. See Figure 10-36 & Figure 10-37
530864 0.435 - 0.438
531017 0.4613 - 0.4643
639195 0.622 - 0.626
639196 0.622 - 0.626
639197 0.622 - 0.626
639199 0.604 - 0.607
639205 0.6514 - 0.6554
639210 0.6483 - 0.6523
652833 0.754 -0.757
627821 0.732 -0.739

Figure 10-37. GTSIO-520 Counterweight Inspection, Repair and Installation

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10-9.1.6. Crankshaft Hanger Blade Bushing Inspection
Crankshaft hanger blade bushings (also referred to as damper bushings) must meet
dimensional specifications in Table 10-37. If the hanger blade bushing exhibits gouges or
scratches, is loose, or is otherwise unserviceable, replace the hanger blade bushing:
Equipment Required
• Borroughs Part No. 8077A Crankshaft Hanger Blade Bushing Removal/Installation
Tool, or equivalent
• Federal Dimension Air Gauge (with appropriate setting ring and air plug) or 
Starrett No. 78 series 3 point contact inside micrometers
WARNING
Removing or installing crankshaft counterweight bushings with
makeshift tools may cause irreparable damage to the
crankshaft that could lead to engine malfunction.
1. The bushing bores must be smooth and cylindrical (no out of round). Replacement
bushings require an interference fit of 0.0015 to 0.003 inches in the bushing bores.
2. Install the new crankshaft hanger blade bushings per Figure 10-38 using the Borroughs
Part No. 8077A Crankshaft Hanger Blade Bushing Removal/Installation Tool.
NOTE: New bushings must be installed into the same positions as the
original. Replacement crankshaft hanger blade bushings are available in
standard and some oversize dimensions.
3. Review Table 10-37 and Figure 10-38 to determine acceptability of parts.
4. Verify the dimensions of the newly installed bushings. Close tolerances require
replacement bushings be 100% dimensionally inspected using calibrated, accurate
measuring equipment (one of the following):
a. Federal Dimension Air Gauge (with appropriate setting ring and air plug)
b. Starrett No. 78 series 3 point contact inside micrometers.
5. Perform a “Magnetic Particle Inspection” according to the instructions in Section 11-3
on the crankshaft assembly after bushing installation to ensure no cracks developed as a
result of bushing installation and the crankshaft is free of cracks.

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Figure 10-38. Crankshaft Hanger Blade Bushing Replacement

Table 10-37. Counterweight Hanger Blade Bushing Dimensions

Crankshaft Installed Crankshaft Installed
Assembly Part Crankshaft Part Diameter “A” Assembly Part Crankshaft Part Diameter “A”
No. No. See Figure 10-38 No. No. See Figure 10-38
530860 5307891 0.4613 - 0.4643 652010 652004 0.622 - 0.626
646623 643687 0.622 - 0.626 652011 652004 0.622 - 0.626
649133 649132 0.622 - 0.626 652039 649137 0.622 - 0.626
649134 649132 0.622 - 0.626 652348 652004 0.622 - 0.626
649135 649132 0.622 - 0.626 652359 649899 0.622 - 0.626
649138 649137 0.622 - 0.626 653020 653019 0.754 - 0.756
649141 649137 0.622 - 0.626 653129 652012 0.604 - 0.607
649144-1 649143 0.622 - 0.626 653136 652013 0.604 - 0.607
649144-2 649146 0.622 - 0.626 653137 652044 0.604 - 0.607
649148 649147 0.622 - 0.626 653138 652046 0.604 - 0.607
649895 649894 0.622 - 0.626 653139 652046 0.604 - 0.607
649896 649894 0.622 - 0.626 653382 653383 0.604 - 0.607
649898 649897 0.622 - 0.626 653697 649137 0.622 - 0.756
649900 649899 0.622 - 0.626 652800 6494742 0.754 - 0.626
652005 652004 0.622 - 0.626 654359 643687 0.622 - 0.626
652009 652004 0.622 - 0.626
Install flush to below surface unless otherwise specified.
1. Part No. 530789 installs flush to 0.015 - 0.005 below surface
2. Part No. 649474 installs flush to 0.005 below surface

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10-9.2. Oil Control Plug Replacement
• Oil Plug Leak Test Fixture (Figure 2-12)
• Oil Control Plug Installation Tool (Figure 2-8 through Figure 2-11)
(differs by engine model)
NOTE: The 2.375-inch diameter collar at the rear of the Oil Control Plug
Installation Tool prevents driving the oil control plug beyond the
specified depth in the crankshaft. Do not use makeshift tools to install the
oil control plug.
1. Remove the crankshaft oil control plug using a 0.4375-20 diameter bolt approximately
8 inches long with 0.4375 -20NF threads and a slide hammer.
2. Inspect the inside diameter of the crankshaft for rust or pitting. Discard crankshafts
exhibiting rust or pitting. Clean the bore of the crankshaft using a pneumatic drill and a
two inch Merrit Wheel. The inside diameter of the crankshaft must be clean and free of
any sludge residue prior to installing a new oil control plug.
3. Two special tools (Oil Control Plug Installation Tool (Table 10-34) and Oil Control
Plug Leak Test Fixture (Figure 2-12)) are required to perform this procedure. The tools
are designed especially for this application. The 2.375-inch diameter collar at the rear
of the Oil Control Plug Installation Tool prevents driving the oil control plug beyond
the specified depth for the plug in the crankshaft (see Table 10-34).

Table 10-38. Crankshaft Oil Plug Installation Specifications

Engine Model Installation Tool Depth of Plug in Crankshaft
IO-360, LTSIO-360, TSIO-360 Figure 2-8 4.44 - 4.46 inches
O-470-G, IO-470-C, H, J, K, L & N Figure 2-9 5.91 - 5.93 inches
O-470-B, E, M, R, S & U
IO-470, D, F, M, S, U & V Figure 2-11 4.96 - 4.98 inches
TSIO-470
520 & 550 Sandcast Figure 2-11 4.92 - 4.94 inches
520 & 550 Permold Figure 2-10 4.66 - 4.68 inches
CAUTION: Do not use makeshift tools to perform this procedure.
Non-conforming tools can damage components, rendering them
unusable.
NOTE: Ensure the threaded hole in the oil control plug is facing toward the
propeller flange at installation.
4. Carefully drive in the new oil control plug into the crankshaft using an air impact
hammer and the Oil Control Plug Installation Tool.
5. Leak test the oil control plug and pressure test the crankshaft by connecting the Oil
Control Plug Leak Test Fixture (Figure 2-12) to the crankshaft using a C-clamp with
neoprene rubber pads as shown in Figure 10-39. Apply 70-80 psi air pressure and close
the air supply. Monitor the pressure gauge for 15 seconds; allowable pressure loss is
not to exceed 2 psi.

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6. After all crankshaft repairs have been completed, restore the helix pattern to the
exposed portion of the crankshaft according to instructions in Section 10-9.3.

Figure 10-39. Crankshaft Oil Control Plug Leak Test

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10-9.3. Crankshaft Plating Overhaul
1. Remove any tin plating on the crankshaft in the one inch area shown in Figure 10-40 by
rubbing a piece of very fine emery cloth, buffing around the shaft to attain a smooth
uniform finish without any scratches.
2. Apply a ½-inch wide strip of 180 grit emery cloth against the newly polished one inch
area on the crankshaft with firm hand pressure to lightly scratch (not score or gouge) a
new helix design in a 30° pattern in the plated area as shown in Figure 10-40. Rub the
emery cloth in the plated area outward toward the propeller flange, counter-clockwise.
For left-hand rotating engines, rub clockwise. The helix promotes proper seating of the
crankshaft oil seal and a better seal to help prevent leakage.
3. After preparing the first quarter portion, rotate the crankshaft by hand so that the next
portion is visible and continue rubbing with the 180 grit emery cloth until the entire one
inch plated area (Figure 10-40) around the crankshaft is lightly scratched with the
helical design.
4. Flush the particles from the crankshaft with mineral spirits.
5. Wipe the plated area with the lightly scratched helical pattern on the crankshaft with
acetone. Ensure the crankshaft is free of any debris or particulate matter to facilitate
clean sealing.
CAUTION: Adequately mask the propeller flange bolt holes and the
forward prop contact surface to prevent paint damage to nut/washer
bearing surfaces.
6. Mask the crankshaft except for the area prepared in the previous steps to prevent over
spray. Apply a single coat of high-performance rust preventive acrylic enamel
(designed for steel), minimal thickness required for coverage, not on load bearing
surfaces according to the paint manufacturer’s instructions to the portion of the
crankshaft which will be exposed to the elements. Allow the paint to dry to the touch.

Figure 10-40. Crankshaft Helix Pattern

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10-9.4. Connecting Rod Replacement
WARNING
Never remove material from a connecting rod. The removal of
metal from connecting rods, crankshafts or pistons, for the
purposes of balancing, is not an approved procedure.
Removing material from a connecting rod will destroy the shot
peen treatment and may cause stress risers. Connecting rods
are matched to limit engine vibration with no more the 1/2
ounce weight variance allowed between connecting rods in
opposing cylinder bays.
CAUTION: For dynamic balance, connecting rod assemblies are
paired with a maximum weight variation of one-half ounce (14
grams) between opposing bays. For this reason, connecting rods
must be replaced in pairs.
NOTE: The allowable weight variation between pistons and connecting
rods does not apply to the entire set. Connecting rod and piston weight
variations are limited to opposing bays.
1. Remove the connecting rods according to the instructions in the primary Instructions
for Continued Airworthiness(Section 1-1.1).
2. Clean the connecting rods with an approved solvent or degreaser. Verify all surfaces are
free of varnish, oil, or residue that will affect reliability of visual, dimensional and
magnetic particle inspections.
10-9.4.1. Connecting Rod Dimensional Inspection
1. Verify the connecting rod and cap mate marks are aligned and the position numbers
stamped on or adjacent to the bolt boss match. Scrap connecting rods and caps with
mate marks that do not align.
2. Visually inspect the connecting rods for corrosion, pitting, discoloration (bluing),
galling, bending, twisting, impact damage or nicks. Scrap connecting rods with any of
these indications.
3. Weigh the connecting rods within opposing cylinder pairs (1 vs. 2, 3 vs. 4, etc.) with a
calibrated scale, accurate to one-half ounce, and record the weight variation. Discard
connecting rod pairs exceeding 1/2 ounce maximum weight variation.
4. Visually inspect the connecting rod and cap parting surface. Contact signatures
resulting from assembly forces are normal and acceptable. Connecting rods exhibiting
fretting signatures, indicated by erosion of the original machining marks, either locally
or over the entire surface, are not acceptable for continued service. Scrap connecting
rods with fretting at the parting surfaces; do not attempt rework.
5. Visually inspect the nut seat area. Excessive fretting signatures indicate material loss.
Scrap connecting rods with edge loading under the bolt head surface contact area.
6. Visually inspect dowel surfaces at the rod and cap bolt holes. Scrap connecting rods
with fretting at the dowel surface.

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7. Align the mate marks on matching position numbers and assemble the connecting rod
and cap by installing a bolt through the cap and rod. With the cap seated firmly against
the rod, you must be able to install the remaining bolt using hand pressure only. Scrap
connecting rods if the bolts cannot be installed by hand.
8. Lubricate the connecting rod bolt and nut threads with clean 50 weight aviation oil.
9. Install and torque the nuts and bolts to Appendix B specifications.
10.Inspect the inside diameter joint of the rod to cap with both bolts and nuts installed and
torqued; mismatch (or a step) must be less than 0.001 inch. To check for a mismatch:
place the rod on a surface plate with the split line at the 6 and 12 o'clock position; use
V-blocks to hold the connecting rod in place. Use a dial indicator mounted on a height
gauge, zero out on one side of the split line and move the indicator across the split line;
a mismatch (or a step) of more than 0.001 inch is not acceptable.
WARNING
Removing and installing the piston pin bushing with makeshift
tools will damage connecting rods.
11. Remove the piston pin bushings from the connecting rod using a Connecting Rod
Bushing Removal/Installation Set (Borroughs Part No. 8098, or equivalent) and an
arbor press.
12.Inspect the piston pin bushing bore and surrounding area for nicks, gouges and
mechanical damage. Scrap connecting rods with any of these indications.
13.Use precision measuring equipment, such as a dial bore gauge or air gauge; verify the
connecting rod meets the dimensional specifications in Figure 10-41 and Table 10-39.
14.Measure the inside diameter of the rod and cap within 30° of the rod and cap joint; take
a second measurement 90° from the first. Both measurements must meet dimensional
specifications in Figure 10-41 and Table 10-39; the difference between these two
measurements is an indication of out-of-round and must not exceed 0.0015 inches.
Scrap connecting rods and caps which fail to meet dimensional specifications in Figure
10-41 and Table 10-39 or exceed 0.0015” out-of-round. Scrap connecting rods and caps
which fail to meet these specifications.
15.Inspect the connecting rod channel rails for nicks, gouges or mechanical damage. Scrap
connecting rods with any of these indications.
16.Perform a “Connecting Rod Magnetic Particle Inspection” according to the instructions
in Section 11-3.1.

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WARNING
Failure to comply with the specifications and instructions
depicted in Figure 10-41 will result in engine malfunction and/
or stoppage.

Figure 10-41. Connecting Rod Dimensions

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Table 10-39. Connecting Rod Specifications

Connecting Piston Pin

Rod Bores Piston Pin Bushing Connecting
1, 2
Connecting Forging Nut P/N Centerline Bore I.D. I.D. Crankpin Rod End
Rod Part Part Distance (No Bushing) Bushing P/N Bore I.D. Width
Engine Model Number Number Bolt P/N “A” “B” “C” “D” “E”

WARNING
If the Hardware listed in the footnotes at the end of the Table is
not available, replace the obsolete connecting rod assembly with
replacement (later) configuration listed for the engine model.

O/IO/TSIO-470 655910 3 646126 654490 Nut 6.6230 1.2340 1.1267 2.3755 1.521
 Superseded Superseded 6.6270 1.2350 1.1269 2.3760 1.525
Small Bore 655000 632041 655958 Bolt
IO & TSIO-520 655004 530658
 654999
IO-346 646778

E- Series 654796 3, 4 646126 654487 Nut 6.6230 1.2340 1.1263 2.3755 1.583
 Superseded Superseded 6.6270 1.2350 1.1265 2.3760 1.587
O-470- 646478 632041 655960 Bolt
2,4,11,13A,15 530658
 A361215
IO-470-
C,G,J,K,P,R

654793 3, 4 646116 654487 Nut 6.3730 1.0620 1.000 2.0615 1.2215

360 Large Bore
IO-240 Superseded Superseded 6.3770 1.0630 1.0005 2.0620 1.2255
646320 626119 655959 Bolt
IOF-240
642268 538684

654794 3, 4 646116 654487 Nut 6.3730 1.0620 1.000 2.0615 1.3015

360 Small Bore Superseded Superseded 6.3770 1.0630 1.0005 2.0620 1.3055
GO-300 646321 626119 655959 Bolt
626128 538684

654795 3, 4 646116 654487 Nut 6.3730 1.0620 0.9230 - 2.0615 1.3015

O-200  0.9235
Superseded Superseded 6.3770 1.0630 2.0620 1.3055
O-300 646322 626119 655959 Bolt
C-90  530192
530184 6 530186 6
C-145
5561 6

655911 3 646126 654490 Nut 6.6230 1.2340 1.1267 2.3755 1.461

IO / TSIO-520 Superseded Superseded 6.6270 1.2350 1.1269 2.3760 1.465
Large Bore 632041 655958 Bolt
655005 4
TSIO-520-BE 530658
646476
646475

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Table 10-39. Connecting Rod Specifications

Connecting Piston Pin

Rod Bores Piston Pin Bushing Connecting
Connecting Forging Nut P/N 1, 2 Centerline Bore I.D. I.D. Crankpin Rod End
Rod Part Part Distance (No Bushing) Bushing P/N Bore I.D. Width
Engine Model Number Number Bolt P/N “A” “B” “C” “D” “E”

655910 3 646126 654490 Nut 6.6230 1.2340 1.1267 2.3755 1.521

Superseded Superseded 6.6270 1.2350 1.1269 2.3760 1.525
L/TSIO-520-AE 655000 4 632041 655958 Bolt
530658
646480
643166

TSIO-520-CE 655911 3 646126 654490 Nut 6.6230 1.2340 1.1267 2.3755 1.461
IO-550 Superseded Superseded 6.6270 1.2350 1.1269 2.3760 1.465
TSIO-550 655001 632041 655958 Bolt
TSIOL-550 646482 530658

IO-550-B29, 655911 3, 7 646126 654490 Nut 6.6230 1.2340 1.1267 2.3755 1.461
B33, B37, C25, Superseded Superseded 6.6270 1.2350 1.1269 2.3760 1.465
C30 655001 632041 655958 Bolt
654440 530658
TSIO-520-
UB17

655910 3 646126 654490 Nut 6.6230 1.2340 1.1267 2.3755 1.521

Superseded Superseded 6.6270 1.2350 1.1269 2.3760 1.525
GTSIO-520
655004 632041 655958 Bolt
530658

1. The most current part number connecting rod nuts and bolts must not be used on or with superseded part number nuts and bolts
2. See Appendix B for Nut and Bolt torque specifications
3. Connecting Rod Assembly must use corresponding Bolt and Nut specified in column 4 of table.
4. Current part number (serviceable) connecting rods must use the most current part number connecting rod new nuts and bolts. The most
current connecting rod new nut and bolt part numbers can be used with old (serviceable) connecting rods of the same style. (Hex head rod
bolts must replace hex head rod bolts, contour head rod bolts must replace contour head rod bolts.)
5. Part No. A36121 connecting rod assemblies utilizing Part No. 632041 forging must be serviced according to table. 
Part No. A36121 connecting rod assemblies utilizing the Part No. 40742 forging must be serviced with Part No. 35972 connecting rod bolt,
Part No. 24804 nut and Part No. MS24665-132 cotter pin; torque to the value specified in Appendix B.
6. Part No. A36121 connecting rod (identified by forging number 530186), A35159 (Identified by forging number 5561) and A35160 (Also
identified by forging number 5561) must be serviced with Part No. 530213 bolt, Part No. 24804 or Part No. 626140 nut and Part No. 639292
cotter pin, torqued to value specified in Appendix B.
7. Used in Balanced Set Part No. 655913

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10-9.4.2. Connecting Rod Piston Pin Bushing Replacement
Replace all connecting rod piston pin bushings at overhaul.
Equipment Required
• Arbor press
• Borroughs Part No. 8098, Connecting Rod Bushing Removal/Installation Set, or
equivalent
• Borroughs Part No. 8111A, Connecting Rod Boring and Alignment Fixture, or
equivalent
• High speed borer of the correct size
• Borroughs Part No. 8042C Adapter Kit, or equivalent (E-Series, 470, 520 engines) or 
Part No. 8072C (240, 300, 360 engines), or equivalent
• Vertical mill, or equivalent, capable of maintaining 1750 RPM.
• Federal Dimension D-2500 or D-4000 Air Plug Gauge with a 1.1268 setting ring and
1.1268 air plug, or equivalent)
• Profilometer
WARNING
Use only the special tools listed. Removing and installing
connecting rod bushings with makeshift tools can damage the
connecting rods.
Verify the piston pin bushing being installed is the correct part number for the application.
Use a Connecting Rod Bushing Removal/Installation Set (Borroughs Part No. 8098 or
equivalent) and an arbor press to install the piston pin bushing as follows:
1. Press out the old piston pin bushing using the Connecting Rod Bushing Removal/
Installation Set and an arbor press. Verify the connecting rod bore is smooth.
2. Verify the new bushing part number. Dip the new piston pin bushing in clean 50 weight
aviation engine oil before placing it in position. The bushing may be chilled to aid
installation.
3. Visually inspect the piston pin bushing bore to determine acceptability of parts. No
nicks or gouges are permissible on the bore after the bushing is removed. Discard the
connecting rod if nicks/gouges are found.
4. Position the connecting rod over the pilot so the mate marks and piston pin bore
chamfer are facing up.
5. Place the piston pin bushing on the pilot so that the bushing split is located 45° ± 5°
from the center line of the connecting rod, facing the crankpin end. Refer to the
Connecting Rod dimensions in Figure 10-41 and Table 10-39.
6. Position the ram onto the pilot.
7. Using the arbor press, carefully press the new piston pin bushing flush with the piston
pin bore.

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8. Bore the new piston pin bushing to the diameter specified in Figure 10-41 and
Table 10-39 according to the “Connecting Rod Piston Pin Bushing Boring” in
Section 10-9.4.3.
9. Visually inspect the connecting rod for nicks or damage that may have occurred during
bushing installation. Scrap connecting rods exhibiting these conditions.
10.Verify the piston pin bushing split line meets Figure 10-41 specifications.
11. Because of the close tolerances required, inspect the new piston pin bushing; note the
bushing bore inner diameter must meet Table 10-39 specifications:
a. Use a Federal Dimension Air Gauge (with the appropriate setting ring and air
plug) to verify that the piston pin bushing is within the connecting rod minimum
and maximum limits specified in Table 10-39.
b. Check the piston pin bushing surface finish with a profilometer. The surface
finish must not exceed 16 Ra.
c. Check the connecting rod bushing for alignment and twist after bushing
installation using the Connecting Rod Boring and Alignment Fixture (Borroughs
Part No. 8111A or equivalent). To check the connecting rod twist, insert the push-
to-fit arbors into the pin and crank end of the rod.
d. Place the connecting rod crank pin end onto the V-blocks.
e. Place the pin end arbor on the two machined parallel steel blocks spaced equal
distance from the center line of the rod, but not less than 6 inches apart.
f. Use a flat feeler gauge to detect clearance between the machined steel blocks and
the pin end arbor. Refer to the connecting rod dimensions in Table 10-39 for
specified limits.
g. To check the connecting rod alignment, rotate the pin end of the connecting rod
to a vertical position and with the arbor resting against a positive stop.
NOTE: The piston pin bushing must be bored to the proper inside
diameter according to the “Connecting Rod Piston Pin Bushing Boring”
instructions in Section 10-9.4.3.
h. Using a dial indicator mounted on a vertical stand resting on the surface plate,
measure the vertical distance of the pin end arbor from the surface plate at points
of equal distance from the centerline of the connecting rod. Compare the
connecting rod measurements to the connecting rod dimensions in Table 10-39.
Connecting rods exceeding Table 10-39 limits must have the piston pin bushing
replaced and reamed or the connecting rod must be scrapped.

Standard Practice Maintenance Manual 10-99

15 Sep 2019
Non-Overhaul Repair and Replacement
10-9.4.3. Connecting Rod Piston Pin Bushing Boring
Equipment Required
• Borroughs Part No. 8111A, Connecting Rod Boring and Alignment Fixture, or
equivalent
• Adapter Kit
• Vertical mill, or equivalent, capable of maintaining 1750 RPM
• Boring tool of the correct sizes

1. Place the connecting rod on the base plate and secure with retainers provided.
2. Select the correct adapter kit and boring tool for the connecting rod.
3. Using a vertical mill, or equivalent, bore the connecting rod bushing to size. Maintain
1750 RPM during the boring process.

10-100 Standard Practice Maintenance Manual

15 Sep 2019