TECHNICAL
BULLETIN
Wärtsilä low-speed engines RT-107
Services 2-stroke Issue 1, 22.04.2011
Servo oil pump pinion bearing Next opportunity
failure Concerned components
Supply unit servo oil pump pinion
bearing of Wärtsilä RT-flex96C-B and
Information to all Owners and Operators of RT-flex84T-D engines in service.
Wärtsilä RT-flex96C-B and RT-flex84T-D engines
Current situation
Concerned are only servo oil pump
bearings of engines built before 2007.
Problem
Too less bearing clearance might lead to
overheating and thus affect the bearing
surface.
Solution
The servo oil pump pinion bearings must
be inspected and in case of damage they
must be exchanged at the latest during the
first dry docking.
Wärtsilä Switzerland Ltd. Tel (24h): +41 52 262 80 10
PO Box 414 Fax: +41 52 262 07 31
CH-8401 Winterthur technicalsupport.chts@wartsila.com
TECHNICAL BULLETIN RT-107
Issue 1, Page 2 / 5
Contents
Page
Introduction 2
Inspection of bearing bush 3
Exchange of bearing bush 5
Introduction
Wärtsilä received reports about failing supply unit servo oil pump pinion bearings
of RT-flex96C-B and RT-flex84T-D engines. Most cases concern the bearing
bush (6) to the camshaft side (forward). Only engines built before 2007 are
concerned as afterwards the clearance of this bearing was increased. With
today’s increased clearance no failures have been reported.
Even with damaged bearing bushes the engine is able to operate without
restrictions over a longer period. However, it is strongly recommended to replace
these bearings at the latest during the first dry docking. In order to clarify the
extent of bearing bush damage, Wärtsilä has a method to inspect the servo oil
pump pinion bearings by endoscope. With such inspections it is possible to give
an indication about the necessary exchange actions and thus being prepared for
the first dry docking.
Supply unit with servo oil pumps
3 4
3 6 7 5
1. Supply unit with servo oil pumps, 2. Gear wheel inspection opening, 3. Servo
oil pump inspection opening, 4. Servo oil pump #3, 5. Section through servo oil
pump #3, 6. Bearing bush forward, 7. Bearing bush aft
Fig. 1
TECHNICAL BULLETIN RT-107
Issue 1, Page 3 / 5
Damaged bearing bushes
1. Squeezed out white metal
Fig. 2
Inspection of bearing bush
The inspection by endoscope is only to be used as guidance as only the forward
bearing bush (6) can be inspected by this method, see Figure 1.
With the endoscope it is possible to enter the gear wheel inspection opening (2)
or servo oil pump inspection opening (3) and route the probe with a tube to the
various servo oil pump pinions, see Figure 1.
For each pinion (1) there is a passage or inspection hole (3) in the casting which
provides access to the forward bearing bush (2), see Figure 3. The probe of the
endoscope needs to be guided through the inspection hole (3) up to the small
gap between pinion and housing (4).
On the running edge of the bearing it is possible to see squeezed out white
metal (2) if the bearing was overheated, see Figure 4. In this case this bearing
has to be exchanged.
The endoscope needs to be of a flexible type as the access inside the supply unit
casing is rather limited. Wärtsilä can provide this service for a servo oil pump
bearing inspection.
Experience showed that mostly the forward bearing bushes are subject to
possible damage. This can be explained by the axial force from the pinion acting
in the same direction.
TECHNICAL BULLETIN RT-107
Issue 1, Page 4 / 5
Inspection of servo oil pump bearing bush and pinion
3 1
1. Pinion, 2. Bearing bush, 3. Inspection hole, 4. Way for bearing inspection
Fig. 3
Damaged bearing bush, view through inspection hole
2 2
1. Bearing bush, 2. White metal squeezed out between bearing bush and pinion
Fig. 4
TECHNICAL BULLETIN RT-107
Issue 1, Page 5 / 5
Exchange of bearing bush
With damaged bearing bushes it is possible to have metal to metal contact during
the engine start. Even though these bearing bushes are not heavy loaded it is
necessary to exchange them at the next opportunity but at the latest during the
first dry docking.
Note:
Wärtsilä recommends exchanging all old type bearing bushes with smaller inner
diameter to new ones as soon as time permits. Only bearing bushes of engines
built before 2007 are affected.
The exchange of the bearing bushes is not easy and thus it is strongly
recommended to order Wärtsilä Services to perform this job.
The forward and aft bearing bushes of the pinion are identical, this means both
need to be replaced at the same time, if they are of the old design and
irrespective if they are damaged or not.
If there is a record of already exchanged bearing bushes it is not necessary to
perform any further action.
For questions about the content of this Technical Bulletin or if you need Wärtsilä
assistance, services, spare parts and/or tools, please contact your nearest
Wärtsilä representative or send your enquiry to:
technicalsupport.chts@wartsila.com
or phone 24hrs Support: +41 52 262 80 10.
© 2011 Wärtsilä Switzerland Ltd. – All rights reserved
No part of this publication may be reproduced or copied in any form or by any means (electronic, mechanical,
graphic, photocopying, recording, taping or other information retrieval systems) without the prior written
permission of the copyright holder. Wärtsilä Corporation makes no representation, warranty (express or implied)
in this publication and assumes no responsibility for the correctness, errors or omissions for information
contained herein. Information in this publication is subject to change without notice.
Unless otherwise expressly set forth, no recommendation contained in this document is to be construed as
provided due to a defect in the engine, but merely as an improvement of the engine and/or the maintenance
procedures relating thereto. Any actions by the owner/operator as a result of the recommendations are not
covered under any warranty provided by Wärtsilä and such actions will thus be at the owners/operators own
cost and expense.
NO LIABILITY WHETHER DIRECT, INDIRECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL, IS
ASSUMED WITH RESPECT TO THE INFORMATION CONTAINED HEREIN. THIS PUBLICATION IS
CONFIDENTIAL AND INTENDED FOR INFORMATION PURPOSES ONLY.
