99 540i sligth misfire and rough idle??

I could believe it was the gasket. one of thing that had crossed my mind.

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Replacing the exhaust manifold gasket really worked well.. Now there is a barely noticeable shake and no fuel smell. The fumes smell was really bad and I did not know where it was coming from. I noticed the aux fan was making this really loud strenuous noise when it turned on, when they scanned it a code came up for the aux fan but I forget to write down the code. I will try to get it tomorrow. they think the mechanic who replaced my radiator messed up the fan some how. I am going to try sort it out tomorrow, any idea's?? This mechanic who changed my radiator is really pissing me off he put 5w40 instead of 10w40 like I told him and now the engine is running a little rougher, he told me there really is no difference but now I know the lubrication from 10w can help a lot. going to drain out the 5w and put 10w and the rislone treatment in.

Wow!! I found the obvious reason for the shaking and rough idle. The exhaust manifold gasket helped a log but the rest of the problem was due to a bad drives side motor mount. I can't believe none if the mechanics that looked at the car did not see the black goop coming out. The truth is both parts needed to be replaced.im just glad I'm not stuck with a partial shake because my mechanic said it was normal for an older car.. Thanks for all the help and insite.

Black goop coming out? Of what?

Originally Posted by caballero

Unfortunately this seals are of very poor quality, BMW knows about this problem and they simply don't care. Google Bisan systems because that's the company that I use when I replace mine, I did mine about two years ago and I believe they cost me about 60.00 dollars good luck

Great tip. Also you may have oil that seeped down to your spark plugs when the valve cover gasket was replaced. I did.

Originally Posted by akillies

bad drives side motor mount.

If you need a DIY:
- Motor mounts (aka engine mounts) and transmission mounts (aka holders) DIYs for the BMW E39 I6 (0) (1) (2) (3) (4) & for the V8 (1) (2) (3).

I said black goop b/c that's what it looked like but the motor mount is either packed with grease or a thick oil. When it starts seepping out around the edges and/or when its visable you know it is bad and needs to be replaced.