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Oil in airbox


Well-Known Member
Mar 28, 2010
I've recently routed both the diffs and the gearbox breather into one tube and plumbed it into the side of the airbox (thereby effectively breathing from the top of the snorkel). However, on checking if any water got into the airbox after Mondays Salisbury Plain outing (which it didn't), I found a reasonable amount of oil in the bottom of the airbox. I'm assuming this can only have come from my breather and is therefore either gearbox oil, diff oil, or a mix of both.

Any ideas if this indicates anything I should be concerned about?

All oils are new (less than two weeks since replacing) and all breather lines were 100% clear before Monday's outing. If nothing to bother about I'll simply disconnect at the original breathers and blow any excess oil out to clear the breathers.

Hi Lorin,
Are your inner axle oil seals good (i.e. recently done)? Obviously(!) something is pressurising the diff(s) or the gearbox - maybe separate off one of the breathers at a time and monitor how you go to try and isolate the source.
Not sure why pottering around the Plain would cause the diffs to get hot, although the drive there or home could have warmed them up. Your 'box is manual, right? In which case I don't know what would make the 'box run hot - oil levels good in 'box and t/case? If it's an auto then you should be able to distinguish between ATF and diff or t/case oil...

Hopefully someone with some real advice will be along soon to educate both of us :twisted:

Hi Andrew,

Yeh front axle was fully rebuilt and I think the rear had new axle seals (I'll check). I'll do as you say and see if I can identify exactly where it's coming from.

Hi Lorin,

I can not help but think this issue is related to your two new leaks thread. If there is enough pressure to blow oil along the breather tubes into the air box then I would have thought there was enough pressure to blow oil past the seals.

I can not think of an explaination though just a link between the two.