PLATE 8N9104 - Caterpillar

Caterpillar: Confidential Yellow
The information supplied in this service letter may not be valid after the termination date of this program. Do not perform the work outlined in this Service Letter after the termination date without first contacting your Caterpillar product analyst.
This Program can be administered either before or after a failure. In either case the decision whether to apply the Program is made by the dealer. When reporting the repair, use "PS4230" as the Part Number and "7755" as the Group Number. If administered before failure, use "56" as the Warranty Claim Description Code and use "T" as the SIMS Description Code. If administered after failure, use "96" as the Warranty Claim Description Code and use "Z" as the SIMS Description Code.
Termination Date
October 31, 1998Problem
The torque on the 6B6682 Nut was found to be out of print specification during a recent audit of air compressor drive gear retaining nut torque.
Affected Product
Model & Identification Number
3116 (9YN4239-4358)
3126 (1WM18739-20407 9ZR598-629 4ES374-384 )
Parts Needed
Inspection Only
1 - 7W6552 Gasket Compressor Replacement
1 - 6B6682 Nut1 - 7C3179 Gear-Compressor (if needed)1 - 6D1004 Gasket-Power Steering Pump1 - 6L1883 Gasket-Compressor Governor1 - 8M7065 Gasket-Compressor Intake1 - OR3391 Compressor Assembly (or as equipped)1 - 7X0521 Washer1 - 9Y4634 Gasket-CompressorAction Required
Check the engine to see if "QT" has been stamped on the block next to the serial number plate. If "QT" if has not been found, continue with compressor inspection/ replacement.
1. Wash Engine and Compressor, if needed.2. Remove the air compressor from the engine.3. Measure the breakaway torque of the 6B6682 Nut in the loosening direction.4. If the torque is below 290 N m (220 ft lbs), then loosen the nut and retighten to 160 N m (120 lb ft). Lubricate the thread and the nut seat with engine oil. If the gear has been removed, wipe clean but DO NOT lubricate the gear bore or the compressor shaft.
If the torque is above 290 N m (220 lb ft), then replace the compressor, gear (if damaged in disassembly), nut and washer.
Tag the compressor crankshaft with "yielded thread" for Reman.
Paint Compressor, if needed.
5. Install air compressor and test.6. Stamp "QT" on the left-rear block rail next to the serial number plate.Service Claim Allowances
Cab Types
RV = Recreational Vehicle (Motorhome, etc.)BU = BusTK = TopKick/KodiakMC = Medium Conventional (Freightliner FL Series, Peterbilt 330 and Kenworth T300)SP = Special (Does not fit one of the above categories) Labor Breakdown
If required, up to an additional 1.6 hours may be claimed using 1803-500 for difficult access in an RV, SP or BU cab type.
When the air compressor requires replacement, claim these additional SMCS codes.
Parts Disposition
Handle the parts in accordance with your Warranty Bulletin on warranty parts handling.