Gear oil smell in Cabin

[UNCLETONY]

I tried searching for awhile but haven't come up with anything yet.

My mom has a 04 AWD Yukon Denali 88,000 miles and she told me she keeps smelling natural gas in the cabin after driving for awhile to the point it gets her sick. I assume what she smelling is gear oil from the front diff after it heats up. I took a quick look at it yesterday there did not appear to any oil coming out the vent cap or from the diff itself. Also the oil was changed at 80,000 with mobile 1 syn.

I had a similar problem with my 2500hd where it was throwing up gear oil out the vent but it never smelt in the cab. The fix for my Silverado was taking out the white vent plug on the side of the diff making sure the baffle was facing down during reinstall and cleaning the vent tube and cap. Problem solved.

Is the smell in the cabin a sign the diff is on its way out? Or am I over thinking this since its AWD?

 

[livingez_123]

Natural gas? gear oil doesn't smell like that. She could have a bad cat, maybe with a hole in it. or she has an exhaust leak and it's coming in the cab. Your over thinking it. The front diffs do go out more often just because of the design of the case is weak. The bearings go first, and you will notice a growl coming from the from end under very light throttle and light deceleration. If you catch it early, you can get by with a bearing kit and have it installed by a ring and pinion guy. I took mine out and dropped it off in the am and picked it up later in the afternoon. total bill was $450.
I would look elsewhere for the smell.

 

[UNCLETONY]

Well I had my mom drop the Denali off in my shop last night so I could work on it first thing this morning. I put Bilsteins shocks all the way around and eliminated the air shocks successfully thanks to info I found on this forum (No dummy lights or messages).

I went to drive the truck and right off the bat I could feel the bearing was out in the front differential. I felt a clunk at light acceleration and turned the truck around. Going to pull it out tomorrow if I have time.

I am figuring I should just have it rebuilt? Instead of getting one from the junkyard? Any thoughts would be appreciated.

With respect, gear oil can smell like natural gas. I have been around excavators and backhoes with planetary final drives and have thought we hit a gas line while digging but it was just the final drives stinking. I'm guessing the oil was getting so hot after driving for a bit that it was blowing fumes out of the vent tube and it was getting sucked into the cabin.

FYI I checked the odometer 90,000 miles for others info. Edit also I am sorry I think I put this in the wrong section if a mod wants to move it the truck is a 04 not 07+

 

[UNCLETONY]

Got the differential back from a rebuilder. Said bearing failed. $500 out of my pocket and she drives like she used to.