2002 Chevy Avalanche Oil from air vent

DCWINFREY1

MEMBER
2002 CHEVROLET AVALANCHE
V8
4WD
AUTOMATIC
173,500 MILES

I have recently started having oil coming out the vent tube on the front differential of my avalanche.
I changed the oil and replaced it with the book reccommended 80-90 wt oil it called for. When I checked the oil it was low. I found out there is a bulletin that reccommends to go to 75-80 synthetic, so I replaced it with synthetic. It is still coming out, but not as bad. Is there some ind of deflector that may have broken off inside the diff that is allowing the oil to be spashed out.

2 Replies

RHALL77

MECHANIC
3,361 POSTS

The plastic vent housing is usually the cause of the leak. That need to be replaced

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Friday, March 6th, 2009 AT 9:06 AM

MERLIN2021

MECHANIC
17,250 POSTS

By now there is a new part to replace the vent tube or you can try fixing yours by following this TSB.
ADVANCE SERVICE INFO - FLUID LEAK FROM FRONT OF VEHICLE (ADD TEFLON TAPE TO FRONT AXLE VENT/PLUG THREADS) TECHNICAL SERVICE BULLETIN Reference Number(s): 03-04-19-003, � Date of Issue: � July 30, 2003 Related Ref Number(s): 03-04-19-003 ARTICLE BEGINNING CONDITION Some customers may comment on a fluid leak from the front of the vehicle. Diagnosis may lead to a concern of an axle fluid leak from the front axle vent connector assembly (or plug in an H2). In some cases, the vent/plug connector may be finger tight, or separated from the axle housing. CAUSE Some vent/plug connectors may exhibit a shrinkage after installation into the axle assembly, which occurs for a time during thermal cycling until it becomes dimensionally stable. CORRECTION Replacing the vent/plug connector may not repair the vehicle in some cases because the new piece may also shrink. A vent connector with a new material that will not exhibit this condition will enter production in the 4th quarter of 2003. Until the new part number vent/plug connector assembly is available from SPO, follow the recommended procedure below. This bulletin will be revised when the new part number becomes available. PROCEDURE Reseal the vent/plug connector assembly with Teflon(R) tape following these steps: 1. Remove the vent/plug connector from the axle assembly. 2. Remove the O-ring from the vent/plug connector. Inspect the O-ring for wear or cracks. 3. Wipe away any excess oil and debris with a clean cloth. 4. Mark the vent/plug connector on the flange in order to identify the starting point of the Teflon (R) tape. CADILLAC: 2002-2003 Escalade, Escalade EXT; 2003 Escalade ESV with All Wheel Drive or Four Wheel Drive CHEVROLET: 2002-2003 Avalanche, Silverado, Suburban, Tahoe with All Wheel Drive or Four Wheel Drive GMC: 2002-2003 Denali, Denali XL, Sierra, Yukon, Yukon XL with All Wheel Drive or Four Wheel Drive HUMMER: 2003 H2 with All Wheel Drive or Four Wheel Drive SECTION: 04 - Driveline Axle Page 1 of 2 ADVANCE SERVICE INFO - FLUID LEAK FROM FRONT OF VEHICLE (ADD TEF...5. Wrap Teflon(R) tape three times around the vent/plug connector threads in a clockwise direction relative to the vane/oil side of the vent. Start and stop at the mark from step 4. 6. Trim the excess Teflon(R) tape from the inner-most threads. Excessive Teflon(R) tape may enter the front axle assembly possibly causing a seal leak. Fig. 1: Trimming Excess Tape 7. Reinstall the vent/plug connector O-ring. 8. Install the vent/plug connector back into the axle assembly. Tighten the vent/plug connector to 15-20 N.m (11-14 lb ft). WARRANTY INFORMATION IMPORTANT: DO NOT tape the inner-most threads of the vent/plug. Excessive Teflon(R) tape may enter the front axle assembly possibly causing a seal leak. IMPORTANT: DO NOT USE RTV Silicone on the vent/plug. Page 2 of 2 ADVANCE SERVICE INFO - FLUID LEAK FROM FRONT OF VEHICLE (ADD TEF...