Oil leak tranny/engine

**Garageaholic** · 07-19-2006, 04:22 PM

I just changed both seals and it's still leaking.. but only when i just drove for a while... not when i'ts just sitting..... but then again, that happens with most oil leaks

**Garageaholic** · 07-28-2006, 05:06 AM

Bump. do I need to let it break in? or does it need to be changed again!... What could I possibly have done wrong? Did I need grease or some agent to seal it up?? or just put it in dry?

**RobertK** · 07-28-2006, 05:18 AM

The rear main seal is very tricky on these cars from what I've been told. I'm having the same problem you are.

The aluminum plate that the rear main seal sets in needs to be thoroughly cleaned with carb cleaner and then you need to take a scotchbrite pad and lightly score the inside of the plate where you tap in the seal.

After you tap the seal into the plate, thoroughly clean the area that the plate bolts to and around the rear of the crank that the seal goes over. Be sure to use some carb cleaner and a scotchbrite pad on it as well. This gives the rubber seal a place to seal into. Make sure you score the rear crank all the way around and not front to back.

Last, put your plate seal in place and use some high temp grease around the rear crank to help the rear main seal.. seal properly and then bolt everything in place. Make sure to use a small amount of grease to lighly cover the seal and the surface of the rear crank. DO NOT slop a bunch on there.

If you are still having problems after this be sure to check the bind plugs located under your valve cover gasket (2 at the front and 2 at the rear of the head.) and also check your oil pan gasket. They both tend to make the rear of the engine leak if you overfill it or top it off. Since the rear main seal plate bottom is sealed by part of the oil pan gasket it is easy to damage it and cause oil to leak out of the back of the pan.

**Garageaholic** · 07-28-2006, 05:27 AM

Thanx for the detailed response, but it's leaking a tiiiiny bit ( a few drops after a drive), then it stops..

Is it worth removing the engine/tranny and digging in to replace it if it's just that small... I mean, i'm meticulous, but it took me 3 weeks to get that engine in the way i wanted it...

**RobertK** · 07-28-2006, 05:31 AM

I would remove the part of the tranmission bell housing that covers the rear of the oil pan. Since the plate that holds the rear main seal also seals against the rear of the oil pan seal it's very possible that the gasket's seal cannot be restored if it was an old oil pan gasket.

Mine was really bad because of my oil pan gasket but when I replaced it I found that I still have a small rear main leak but not as bad as it was when the oil pan gasket was bad.

**Garageaholic** · 07-28-2006, 05:47 AM

Yeah, i replaced the oil pan gasket as well..

Should i let it break in and eventually it will seal itself... or replace it now.. It's going to be a bitch and a half...

**RobertK** · 07-28-2006, 06:30 AM

It shouldn't leak at all if it was done right the first time. I've heard other mechnics complain about having to replace the rear main seal in some BMWs 2-3 times before they got it right.

Chech your bind plugs first though

**rs4pro3** · 07-28-2006, 06:48 AM

m30's don't have those plugs, but did you replace the gasket on the plate that bolts to the back of the head?

**netcsk** · 07-28-2006, 07:32 AM

I'm heading in come a few weeks to do my rear main seal again. I've delt with it for about 15 months now and don't want to drop oil anymore. If I don't get it right this time, I'm going to be pretty pissed off.

**Garageaholic** · 07-28-2006, 08:01 AM

Originally posted by rs4pro3

m30's don't have those plugs, but did you replace the gasket on the plate that bolts to the back of the head?

Sure did. I did it dry though. No grease or gasket sealer on there. Maybe that was the problem..... If that's the case. is this going to get worse?? or remain the same..

Also ely, i have a little extra oil than i should in the engine. Could this be causing it?

**rs4pro3** · 07-28-2006, 09:28 AM

a little extra oil won't hurt. I did that gasket with sealer when I did mine, it's just a guese as it could be leaking down the back of the block.

**E30/M30** · 07-30-2006, 01:44 PM

I used sealer on that little gasket at the back of the head but when the bolts tightened up it pushed the gasket out and split it so it was replaced with out any sealer and it's fine now.

Did you put the bolt in with the sealing washer back in where it came from ?

Where your old crank seal rubs against the crank has it worn a grove ?

If it has then you have a little leeway to move the seal forwards or backwards in it's mounting so the seal seals on to a flat unworn surface on the crank.

**Garageaholic** · 07-30-2006, 06:10 PM

I have to take my engine out and check it out... i haven't seen it yet, but i will do it this week... wish me luck. i do NOT want to remove this engine. i am very unhappy right now. but i'm not settling. I'm doing a quality job, not a half assed job. i will fix this

wish me luck . i will take all your comments into consideration and answer them all when i have visual inspection on what's going on

**Garageaholic** · 08-02-2006, 03:10 AM

Ok I think I figured it out.....

So after thinking about it over and over.. and taking the tranny, oil pan, rear seal carrier out yesterday... I realized that the transmission is awefully greasy inside the bell housing by the throwout bearing/release fork/etc..... Then it dawned on me....

There was no leak from the tranny OR the rear engine seal (although i'm replacing them again anyway) What happened was that when I drove, inside of the tranny bell housing got hot enough to kinda "melt" the excess bearing grease that I put in there. And i was liberal with the amount that I had put in...So I believe that It got hot enough in there to melt the grease to a liquid and then it came dripping out of the tranny/engine area... I'm almost sure of it..

It was a waste of time and work and money, but I think that is the problem. Like 90% sure. The other 10% is used replacing the seal and gaskets anwyay....
Any thoughts?

Oil leak tranny/engine

Oil leak tranny/engine

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