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Makes 🢒 Chevrolet 🢒 2003 🢒 Kodiak C-Series (Crew) C4/C5 🢒 Bulletins 🢒 Oil Leak at Oil Cooler to Engine Block Mating Surface (Replace O-rings, Apply Sealant)

Oil Leak at Oil Cooler to Engine Block Mating Surface (Replace O-rings, Apply Sealant)

Subject:Oil Leak at Oil Cooler to Engine Block Mating Surface (Replace O-rings, Apply Sealant)

Models:2001-2005 Chevrolet Silverado 2500/3500 Series Pickup Models
2001-2005 GMC Sierra 2500/3500 Series Pickup Models
2003-2005 Chevrolet Kodiak C4500/5500 Series Models
2003-2005 GMC Topkick C4500/5500 Series Models
with 6.6L Duramax™ Diesel Engine (VINs 1, 2-- RPOs LB7, LLY)


This bulletin is being revised to add a new sealant part number. Please discard Corporate Bulletin Number 02-06-01-023D (Section 06 -- Engine/Propulsion System).

Condition

Some customers may comment on oil leaks at the engine oil cooler.

Cause

Minor imperfections in the engine block machined surfaces at the oil cooler interface may allow oil seepage past the oil cooler O-rings.

Correction
  1. Inspect for other oil leaks that may be perceived as an oil cooler leak. An oil leak from one of the main bearing cap side bolts may appear to be coming from the oil cooler.
  2. If the oil cooler is leaking oil, remove the oil cooler from the engine. Use care to remove only the five bolts that hold the oil cooler to the engine block. Refer to the Engine Mechanical sub-section in the appropriate Service Manual.

    3. Object Number: 870004 Size: SH
    (1)Apply sealer to this area
    (2)O-rings
  3. Remove the O-rings from the oil cooler and discard the O-rings.
  4. Clean the mating surfaces of the engine block and the oil cooler.
  5. Install new O-rings (2) to the oil cooler.
  6. Apply sealant (1), P/N 12378521 (in Canada, use P/N 88901148 ), to the oil cooler as shown. Do not apply sealant to the O-ring grooves on the oil cooler.
  7. Install the oil cooler to the engine. Refer to the Engine Mechanical sub-section in the appropriate Service Manual.
  8. The maximum working time of this sealant is 20 minutes. The sealant will be fully cured in 24 hours. The assembly may be filled with engine oil immediately after applying the sealant and torquing the bolts. The engine can be started after 2 hours of cure time.

Parts Information

Part Number

Description

Qty

12378521(US)

88901148 (Canada)

Sealant

1

Parts are currently available from GMSPO.

Warranty Information

For vehicles repaired under warranty, use:

Labor Operation

Description

Labor Time

J3121

Cooler, Engine Oil (Auxiliary) - Replace

Use published labor operation time