Oil leak help! (Photos)

[StartX5]

While replacing O2 sensor (postcat) i found some wet oil from the area between transmission oil pan and transfer case. The oil leak seems a while ago and i don't see any oil drops in the area but it's wet. I checked transmission oil pan gasket all the way round and oil is not coming from there. I changed transfercase and rear/front differential fluid at 75K miles, all i remember when i pumped transfercase fluid it spilled out some and i cleaned right after the bolt locked.

Look at the photos below, do yo know where is the oil coming from?

[PUREVIL]

Can't say where it's coming from but it does look like the oil has been transferring around in wet conditions. The water eventually evaporates and leaves that oily residue making the leak look much bigger and worse than it actually is.

I'd degrease/pressure wash it clean and monitor it. The leak will present itself.

[thedweeb]

Check out the post by Dville...transfercase removal and go to page 11 ( dont know how to place a link) looks like the same fault as you have.

Dweeb

[StartX5]

Dweeb, thanks so much for your information. I was in that thread last night too but i did not have chance to read to page 11 (to page# 9 and stopped).
I cleaned wet and moisture area last night and today i drove around 50 miles and checked again, nothing there so may be it's low leak. I looked at it 2 more times to make sure exactly where's oil coming from. And it's from transmission gasket seal: the area where the junction between the rear shaft, tran shaft and transfer case.

I need to replace gaskets numbers 3 and 5 from diagram below:


My question is: do I need to change transmission oil when replacing these gasket? Does anyone know?

[joeboch348]

I wish mine leaked that little

[StartX5]

joe, did you replace the gaskets? tell me in detail if you did. it's no more leak since i cleaned the leaking area couple days ago but not yet, let see what happens in the future. I cleaned it very well and oil was from the gasket between transfer case and transmission output shaft. If it leak more in the future, i replace the gasket. This is a big job and i will need a helper and a lift for it.
I mentioned this to my brother in law in Boston and he said many many BMWs oil leak from that area when cars reached to 60-70K miles or 5,6 years old. I sent him photos where oil leak he said alot og cars leak like this but they don't know until it drop alot of oil.

When car is runing oil pressure from transmission extention where rear shaft, spline and transfer case located and due to gasket aging, oil leak from there. This happens when cars is reaching to higher mileage or aging, it's normal but we should monitor it.

[joeboch348]

I haven't done anything yet but keep wiping up the puddles. Waiting for summer.

[StartX5]

yes joe, that's what i plan too. Waiting for a little more, few more months see what happens then if necessary i will do it during the summer time.

[StartX5]

After cleaning wet oil/moisture ared by gunk engine degreaser and driving for a week for ~330 miles both highway and local mileage. Wet oil leak was gone, it's dry and in the good shape.
The wet and moisture area pictured above was coming from oil filter housing gasket leak that i repaired before. no leak from either transmission extension gasket nor transfer case.

[SF2000x5]

Originally Posted by joeboch348

I wish mine leaked that little

Tell me about it. I should degrease and track the leak(s).