[paulthevol]

Hey guys,
I would appreciate some opinions about an oil leak that I have. First off, some info about my situation. The car is a 2008 335i automatic, with 87,100 miles. I have already replaced the VCG, OFHG, and transmission pan gasket. Most importantly, I replaced the oil pan gasket 2 years ago (at 62,900 miles). About a week ago I noticed oil on the garage floor, so I pulled the belly panels, lifted the car, cleaned everything up, and drove the car. I then pulled the car in the garage the lifted it again. The leak is either coming from the rear main seal or the oil pan gasket AGAIN. Here is what is confusing me. The areas marked with the blue circles is where I first started seeing oil leakage. After some time, I see oil leaking at the area circled in red. The area circled in red is above the oil pan gasket. Also, when I remove the black plastic cap from the transmission housing, there is a small amount of oil in there.

Last week I re-torqued the oil pan bolts and I still have a leak.

Any comments or opinions would be appreciated. If you need any other info just leave a reply.

[paulthevol]

So, I dropped the subframe and removed the oil pan only to discover that its the rear main seal that is leaking. In this picture, you can see that the rear main seal is wet and there are drops of oil in that area.

Knowing what I know now, I would have just bought or borrowed a cheap boroscope and looked up into the the torque converter housing.

I hope this helps someone down the road.

Thanks for all your comments and suggestions. I appreciate it.

[soulcrusher]

Hey did you replace the rear seal on your own or pay a mechanic? I may have to this job

[paulthevol]

"Hey did you replace the rear seal on your own or pay a mechanic? I may have to this job"

I sold the car. I got tired of the endless breakdowns and something always going wrong. However, I would have had to pay a mechanic for the rear seal replacement. You need to drop the transmission to replace the seal.

[Soravia]

Looks like mine is leaking in rear main as well as oil pan gasket. It's both minor but they are there. 2011 with only 62k miles.
I bought LiquiMoly snake oil to see if that will help, along with the high mileage rated Mobile 1 oil.
I checked and replaced the oil level sensor gasket. It wasn't leaking.

If rear main I'll limp it until clutch replacement in about 10k more miles?

I wonder if NOT using OE gasket for oil pan will help?

Gasket makers? Custom cut gaskets?

[mweisdorfer]

Originally Posted by Soravia

Looks like mine is leaking in rear main as well as oil pan gasket. It's both minor but they are there. 2011 with only 62k miles.
I bought LiquiMoly snake oil to see if that will help, along with the high mileage rated Mobile 1 oil.
I checked and replaced the oil level sensor gasket. It wasn't leaking.

If rear main I'll limp it until clutch replacement in about 10k more miles?

I wonder if NOT using OE gasket for oil pan will help?

Gasket makers? Custom cut gaskets?

There's a DIY on YouTube how to drop the transmission on an e90. That will get you to the RMS.

If it's the RMS, you are way better off using an OEM gasket with Ultra Grey.

Conventional wisdom would be to change the oil pan gasket and Sandwich it between two beads of Ultra Black. If you still have a leak, it's the RMS. No harm in changing the oil pan gasket. It's going up leak eventually! By using Ultra Black with an OEM gasket, you've increased its longevity.

Also to change out the PCV valve with an upgraded version & change out the PCV breather hose next to it, that has the one way valve. Both of these two items will cause excess pressure in the system when they are not working correctly and lead to a RMS leak, as a result.

[Soravia]

Mine is LCI N52. Looks like it doesn't have a PCV to upgrade to. It doesn't make the high pitch noise. Just changed oil. I'll use engine flush in a month and change oil again. I think that will help clear anything that may be clogging anything in the system. I'll put in oil saver again to help with the seals on next oil change in a month. Valve Cover seals have yet to leak.