This is kind of a weird one.

When I got home tonight, I noticed an oil spot on the garage floor. At first I thought it had come from the rear end. But after I pulled the car in, I realized that it was too far to the right.

Upon inspection, I noticed that the right axle housing had some oil on it right around the label. Then I noticed a small, cylinder or cap covering a bolt on top of the axle housing - perhaps some kind of plug. (See pic.) The cylinder is loose and will woble if touched, but it doesn't come off.

Does anyone know what this is? Should it be loose? Anyone else see oil in that spot? Should I worry. The car only has about 2000 miles.

Thanks

 

Vent cap I believe.
Should be loose.
Shouldn't lose fluid, but can under certain circumstances.
(Such as being upside down or overfilled).
It may just be because of humidity and temperature if it is very little fluid.

 

I thought that might be the case, but couldn't figure out why there would be a vent cap on top of the axle housing.

Thanks.

 

Yep, it's a vent. The axle would be air tight without it. As the gear oil (and the axle itself) heats up the axle would become pressurized from the expanding fluid. The seals aren't designed to hold pressure, thus the need for a vent cap. You really shouldn't see any seepage however.

 

i had the same thing on my '03 - I actually had my mechanic take the vent off because the vent cap would strike my flowmaster exhaust pipe if I hit a bump in the road. it would have ended up putting a dime size hole in the over axel pipe if i didnt remove it. No change since removed.

 

Its definetely a vent and the cap is there to keep stuff from getting in (short of fully submerging the axle housing).