[villaan]

Hi all -

I have a 2007 335xi with a pretty healthy oil leak. I've had it up on a lift for a week just letting it sit to see where the oil leak is coming from. The oil is leaking from where the oil pan connects to the bellhousing of the transmission. Any experts out there that can help me diagnose whether this is more likely the oil pan gasket or the rear main seal?

I was geared up to tackle the oil pan gasket - but am worried I should take to a indy shop if its more likely the rear main seal.

Thanks in advance!

Pic:
https://www.amazon.com/photos/share/...6BV5P1WI9ckIA2

[aj90]

Hi,
For some reason your picture isn't showing. When my car had an OPG leak, oil dripped from the rear bolts and into the rear seal area. If you have oil around the gasket as well as the rear seal, then I would say that it is the OPG. If it's only around the rear seal then it's the seal.

OPG leak on my 330
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View post on imgur.com

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[BMW_SYNERGY]

Looks like the oil pan gasket has never been replaced before judging by the original bolts still one there. I would say it's the oil pan gasket. They usually tend to leak from the sides and then it runs down in that back area.

If it were my car I'd start with that since you say you're comfortable tackling that job (Gonna need it anyway). Give it a good cleaning and I bet we'll be good to go. You may need to clean off some residual oil that gets trapped in small areas after your test drive, but if done correctly you'll be leak free and have saved yourself hundreds compared to an independent shop.

[mweisdorfer]

I'd do the Oil Pan gasket myself. If it turns out its the rear main seal, then at least you did the Oil Pan gasket. At some point in time, it will go. There is no question on that.

There is not one diy on this forum for a rear main seal. Best to take it to an Indy, if you don't know exactly what you are doing

[tylerboland01]

Get some fluorescent dye and a UV light, clean the pan with some heavy degreaser and drive around for 30-40 miles under 40mph to avoid excessive splatter. It should be pretty easy to tell where the oil is coming from.

If you have to drop the trans you may as well do the pan at the same time.

[Efthreeoh]

If the oil pan is leaking, the leak at the rear of the pan can make it appear like the rear crank seal is bad. When I did the clutch in my car at 293K I thought the rear seal was leaking. I discovered that the design of the N52 (N54 I assume too) has the rear of the pan protrude into the bell housing behind the flywheel. When the pan gasket leaks, the oil from the leak gets spewed all over the inside of the bell housing and drips out the inspection hole (this is for the manual trans drivetrain). If you want to see what I mean, go find my DIY for the N52 clutch replacement, I have pictures showing how bad the oil gets spewed around inside the bell housing from the pan gasket leaking. Have the pan gasket repaired and the bottom of the bell housing cleaned, then keep an eye on it. My rear seal at 332K is still leak free.

If you find out then that the rear seal is indeed bad, the repair is expensive because the trans needs to come out, but there is no cost savings by doing the pan gasket and pulling the trans (to replace the seal) at the same time. So there is no need to speculate the rear seal is bad and replace it during the pan gasket repair unless you are absolutely sure the rear seal is bad. You can't tell until you seal up the pan gasket leak first.

[antonmn]

I did my OPG once, then paid to have it done again, before realizing it was the RMS. But even then we didn't really know it was the RMS until we dropped the trans. One week in January it started to dump a quart every 150 miles... not good. Steady drip before that - looked the same as the pic.

The RMS had somehow spun in the bore. Weird, and expensive.

[Efthreeoh]

Finally was able to look at the pic. That's an oil pan gasket leak.

[cybermgm23]

Originally Posted by Efthreeoh

If the oil pan is leaking, the leak at the rear of the pan can make it appear like the rear crank seal is bad. When I did the clutch in my car at 293K I thought the rear seal was leaking. I discovered that the design of the N52 (N54 I assume too) has the rear of the pan protrude into the bell housing behind the flywheel. When the pan gasket leaks, the oil from the leak gets spewed all over the inside of the bell housing and drips out the inspection hole (this is for the manual trans drivetrain). If you want to see what I mean, go find my DIY for the N52 clutch replacement, I have pictures showing how bad the oil gets spewed around inside the bell housing from the pan gasket leaking. Have the pan gasket repaired and the bottom of the bell housing cleaned, then keep an eye on it. My rear seal at 332K is still leak free.

If you find out then that the rear seal is indeed bad, the repair is expensive because the trans needs to come out, but there is no cost savings by doing the pan gasket and pulling the trans (to replace the seal) at the same time. So there is no need to speculate the rear seal is bad and replace it during the pan gasket repair unless you are absolutely sure the rear seal is bad. You can't tell until you seal up the pan gasket leak first.

^^^ this

[ny325]

Approximately how much to repair the oil pan gasket on a 2008 E90 328i at Indy shop? Thanks. Dealer price was $1,200.

[cybermgm23]

Originally Posted by ny325

Approximately how much to repair the oil pan gasket on a 2008 E90 328i at Indy shop? Thanks. Dealer price was $1,200.

depends on a lot of factors, where you are, what kind of parts you want used and how good of a shop. you should call around.