E34 525i Leaks and noises

[sdobrosky]

Alright, so I have been unable to locate my mystery leak - it is either Transmission oil or engine oil that is leaking. The car leaks only after being driven and while driving - if it sits for a while - its fine. The fluid is dripping down between the bell housing of the transmission. It could be the head gasket but I have heard that coolant mixes with the oil in that case and that is not happening. I already replaced the valve cover gasket just for insurance but it seems like the car is leaking more now that I did that. The car never overheats but it shakes and vibrates horribly between 50-80 mph.

I have not looked at the engine or transmission mounts yet, but the vibration is pretty bad (I have driven my E36 with bad mounts and it did not feel like this). Also - the vibration is not constant, it vibrates and then is fine for a second, then vibrates again. This is a constant cycle and I really notice it on the highway.

My concern is the vibration and the fluid leaking. The engine oil level is normal and the fluid looks like oil (not transmission fluid). Are there any other places of common leakage besides the valve cover, head gasket, rear main seal, etc.? Is the vibration engine related or transmission related? Please help ....anyone....I am going to take it to get looked at if I don't get any ideas soon and I fear that problem is going to cost mucho $$$$$.

Thanks.

[moroza]

Speed-dependent vibration is a suspension problem, not a drivetrain problem (unless it's got something to do with the differential, which doesn't seem to be the case). Leaking oil is a drivetrain problem (unless it's a shock absorber, which isn't the case), so you've got two problems. What suspension work have you done? Are your tires balanced? Any recent brake work?

[sdobrosky]

Well I just got the car and to be honest I am pissed. The guy told me that it leaked a little bit...of course that is not the case, it leaks a whole lot. I have not really done any major work on it because I haven't had it that long. I was going to get the tires balanced just to rule that out. My main concern is the leak just because I cannot locate it. But I had not thought about the suspension - I'll take a look at that and maybe work from there. thanks for the information.

[sdobrosky]

Also - to be honest I am not really familiar with the 5 series. I have had a 3 series for a while and know it like the back of my hand, but anyone have any major differences between the two types of BMWs besides the size? I know the engine in both of my cars is an M50 so that helps me out a little when working on the 525.

[moroza]

I've never tried to diagnose a leak before, but something that might work is cleaning up any suspected areas and seeing if it reappears there. You mentioned the leak possibly increasing since you replaced the valve cover gasket. What kind of gasket did you use, and did you use any sealing compound?

By clean up, I don't mean the whole dismantling-pressure washer-degreaser-polish 9 yards, just wipe it down with a bunch of rags or paper towels. If it's coming from somewhere near the back of the engine, you'll have to feel your way around there, so clean up just enough that it feels relatively dry to the touch.

There's also some UV-reactive stuff that you can put in fluids to see where they're coming from, but I know next to nothing about it, much less have any experience using it.

AFAIK, there's no real difference between the drivetrain of an M50-powered E36 and an M50-powered E34, assuming both are manuals or automatics. What kind of transmission do you have, anyway?

Regarding the vibration, is it in fact strictly speed-dependent, having nothing to do with engine speed? Does any particular kind of maneuvering (a turn one way or other) affect it? Can you feel it through the steering wheel, the seat, or both?

[Felixdacat]

When the car is burning the fluid off, does it smell sweet and kinda dry? Possible trans fluid. Auto trans fluid is supposed to be red in color. If it hasn't been changed in a very long time it will become brown. Do you have an Auto?

[sdobrosky]

Both of the cars are auto...I think I will try to give it a real good clean and see if I can diagnose it that way. The leaking has unfortunately become worse. It is not just a drip from right back of the engine block, there is a small puddle. On the valve gasket, I did use sealing compound and that area is still dry after the engine has been run. In regards to the vibration, it is not just one part of the car (steering wheel, seat, pedals) that vibrates or shakes....it is the entire car - I mostly notice that the dash shakes. Once again, this is mainly noticeable from 50-80 mph. Finally, when the fluid burns off, it does not smell sweet - it smells like burning plastic and if you look just right there is very faint smoke (like the fluid is dripping on the exhaust manifold. The fluid on the ground looks like oil - it's not red - I guess it could be very old transmission fluid (brown), the consistency is the same as oil and it smells like oil.

[e34gasm]

Can you tell where the vibration is coming from? If it's from the wheels, then moroza's right: it's probably suspension issues. Does it get worse under braking? My e28 had that problem and it was the bushings. Cleared right up when i put grunts bushings in. Also, check your wheels, you may have just thrown a wheel weight; speed dependent vibration is notoriously linked with improperly balanced wheels. Even if the weights are still there, the greasemonkey who did it may not have done a good job. Most balancers only go up to 55mph. In the past, I've paid extra to have an on-the-car 100mph balance done, and it was silky smooth after that.

But if the vibration is coming from the center of the car, the transmission tunnel, you may need a new guibo and center bearing. Even if it's only one and not the other, replace both. you don't want to have to go back and do it twice because I...er, you were too cheap to do both at the same time (sound like i'm speaking with experience? hehe).

[hooRAH]

Good chance the leak is still coming from the VC gasket. I replaced mine about 2 years ago. Never had any oil on the ground before or after. Had my car on the lift (doing the transmission) and one of the techs was just looking around, stuck his head up, and said "You've got a VC gasket leak".

I insisted that I didnt, that I had replaced the gasket recently. Sure enough, when I looked up there, there was a tiny leak dripping down the backside of the engine that you couldn't see at all from the front. Didn't leak enough to leave a puddle, it just kind of made the backside of the engine a little moist.

I also had to set the VC gasket like 5 times in my girlfriends camry because it still leaked after each time. I finally got it with a good coating of sealant and careful torquing of the bolts.

VC gaskets aren't necessarily hard, but can be a bit difficult to set perfectly. Add a slightly warped VC (mine was) and it makes it harder.

Alternatively, it could be the rear main seal.

[sdobrosky]

Thanks for the info guys. I will definitely get the wheels balanced as a cheap rule out for the issue. I have also heard of replacing a guibo and center bearing so that may be a good option as well. I guess there is always a possibility that I set the valve cover wrong but it really seems like too much of a leak for that. I hate the thought of the issue being the rear main seal....I don't have a lift and I have heard it is very difficult without one. And just to answer a question - the vibration does not get worse with braking - it doesn't seem like they are a part of the problem.