7/30/2017 G3306 Gas Engine G6X00001-UP(SEBP3728 - 26) - Documentation
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Product: GAS ENGINE
Model: G3306 GAS ENGINE G6X03678
Configuration: G3306 Gas Engine G6X00001-UP
Testing and Adjusting
G3304 and G3306 Engines
Media Number -SENR7939-08 Publication Date -01.09.2011 Date Updated -01.02.2017
i02024662
Compression
SMCS - 1215-081
Table 1
Tools Needed Quantity
193-5859 Cylinder Pressure Gauge Gp (Gas Engine) 1
Cylinder pressure can be measured during inspection of the spark plugs. The condition of the following items
can be tested by checking the cylinder pressure: valves, valve seats, pistons, piston rings and cylinder liners.
A loss of cylinder pressure or a change of pressure in one or more cylinders may indicate the following
conditions. These conditions may indicate a problem with lubrication:
Excessive deposits
Guttering of valves
A broken valve
A piston ring that sticks
A broken piston ring
Worn piston rings
Worn cylinder liners
Measure the cylinder pressure of an engine after approximately 250 hours of operation. Record the data.
Continue to periodically measure the cylinder pressure. Comparing the recorded data to the new data provides
information about the condition of the engine.
Note: Cylinder pressure is one of the factors that help to determine the overhaul interval. Refer to the engine's
Operation and Maintenance Manual.
If the cylinder pressure has risen by one or more compression ratios, the engine needs a top end overhaul in
order to remove deposits. Failure to remove the deposits will increase the chance for detonation. Severe
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7/30/2017 G3306 Gas Engine G6X00001-UP(SEBP3728 - 26) - Documentation
guttering of the valves will occur.
To measure the cylinder pressure, use the 193-5859 Cylinder Pressure Gauge Gp (Gas Engine). Use the Special
Instruction, NEHS0798 that is included with the gauge. Use the following guidelines:
Remove all of the spark plugs.
Fully open the throttle plate.
Minimize the cranking time. This will enable a maximum consistent cranking speed for the check. Also,
the battery power will be conserved.
Illustration 1 is a graph of approximate cylinder pressures for engines with different compression ratios.
Illustration 1 g00760309
Approximate cylinder pressure chart
(Y) Cylinder pressure in kPa (psi)
(X) Compression ratio
(1) Normal range for cylinder pressure
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7/30/2017 G3306 Gas Engine G6X00001-UP(SEBP3728 - 26) - Documentation
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