Doing my usual under hood check, I noticed a small bit of oil residue under the master cylinder aroung the hard brake lines. It seems to be coming from a vent line that is clip mounted next to the brake lines. Any idea where this vent comes from? I am bringing Kong into the dealership this week for it and a few other issues.

Doing my usual under hood check, I noticed a small bit of oil residue under the master cylinder aroung the hard brake lines. It seems to be coming from a vent line that is clip mounted next to the brake lines. Any idea where this vent comes from? I am bringing Kong into the dealership this week for it and a few other issues.

Did you ever find out what this was? I just developed the exact same problem last week. Seems fine around town but will sometimes blow oil from that vent after long highway stints.

It was a bad vent/vent valve ...take it to the dealer..it is a warranty item.

cool, thanks!

That is the vent for the front differential.
There have been some issues with those leaking, and a new vent on the end not fixing it. The fix is to replaced the vent line with a larger diameter hose.

So maybe I should start with that before I hit the dealer, loose my truck for probably two days, and pay them $100/hr to not fix it in the end? (I'm out of warranty at this point).

So rather than try to put a new fitting on the differential (if it even can be changed), can I run a reducer from the new, larger diameter tubing to short lengths of the stock tubing at the vent and diff. ends?

Anyone perform this fix at home successfully?

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JohnnyRPM:
So maybe I should start with that before I hit the dealer, loose my truck for probably two days, and pay them $100/hr to not fix it in the end? (I'm out of warranty at this point).

So rather than try to put a new fitting on the differential (if it even can be changed), can I run a reducer from the new, larger diameter tubing to short lengths of the stock tubing at the vent and diff. ends?

Anyone perform this fix at home successfully? </div></BLOCKQUOTE>

I have to believe the fix is an easy one. I would go to the parts counter and discuss with one of the techs. Get the right assembly and install yourself.

yes, you're right, use the reducers and just make the tube between the diff and the vent a larger diameter. Doesn't have to be a lot larger, just the next size up. I think it's 5/16 hose if I remember right.

Great...is there a tsb on this by any chance? I couldn't find one in the service manual browser app app I'm running.

No bulletin on this, it was something suggessted by tech assist a year ago when we ran into one that we couldn't get to stop leaking, and that has fixed several since then.

Front Axle Vent Fluid Leak - keywords hose lube repeat tube #PIP3454 - (Jun 1, 2005)
Front Axle Vent Fluid Leak
2003-2005 Hummer H2

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
Front axle fluid leak that appears to be from the end of the axle vent hose.

Recommendation/Instructions:
Increasing the inside diameter of the vent hose will help prevent the lube from being forced out of the hose during normal venting. Replace the existing vent hose with a section that is 5/16" (8 mm) inside diameter and of the same length as the original hose. Use a worm gear style hose clamp to retain the hose to the housing and also the vent cap to the other end of the hose.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

Excellent....thanks!

Re: Oil leak at vent tube...
 

Has anyone had to do more than just increase the size of the tubing for the fix? My truck has this same problem following a good road trip. I was really nervous until I got home and did a search. This forum is such a relief!

Jimmy