SFN-20250318A Rust Preventative Oil at Flywheel HouMisdiagnosed as Rear Crankshaft Seal or Crankshaft Collar Malfunction.

TICO Document #: SFN-20250318A (Cummins Technical Service Bulletin: TSB140104)

Description of Procedure:

Residual rust preventative oil from manufacturing can be present at the rear of the engine and be incorrectly diagnosed as a rear crankshaft seal malfunction or a crankshaft collar malfunction on rear gear train engines.

During engine assembly, rust-preventative oil is applied to the inside of the flywheel housing. Excess rust-preventative oil droplets can be visible on the outside of the transmission or flywheel housing, similar to what is shown in Figure 1 below. The use of tracer dye, Part Number 3376891 or 2892320, is not effective in identifying the leak path, as the preservative oil also has a Fluorescent property.

Note: This document only applies to engines equipped with dry flywheel housings.

Units Affected:

• B6.7 CM2350 B121B

• B6.7 CM2350 B135B

• B6.7 CM2350 B148B

• B6.7 CM2450 B155B

• ISB6.7 CM2350 B101

• ISB6.7 CM2350 B103

• ISL8.9 CM2150 L110

• ISL9 CM2150 SN

• ISL9 CM2250

• ISL9 CM2350 L101

• ISL9 CM2350 L111

• L9 CM2350 L116B

• L9 CM2350 L119B

• L9 CM2350 L123B

• L9 CM2450 L126B

• QSB6.7 CM2350 B105

• QSL9 CM2250

Note : This document only applies to engines equipped with dry flywheel housings.

Instructions:

1. Clean external surfaces of all oil around the suspect area.

2. Remove the plug in the bottom of the flywheel housing.

3. Spray electrical contact cleaner, Part Number 3824510, or equivalent, into the flywheel housing.

4. Wipe surfaces clean.

5. Operate the engine for at least one hour at idle and monitor for leaks.

• If oil is not present after performing the Verication steps above, no further action is required.

• If lubricating oil is present, refer to published troubleshooting for lubricating oil consumption excessive in the corresponding Service Manual.