I have a 2003 325i. I have had an ongoing issue with the car since it had about 10K miles on it.

After it has sat in the garage all night- it squeals on the initial start. the squealing noise sounds like a bearing or a water pump but lasts only about 5- 10 seconds.The dealer has replaced the vanosunit twice, several seals, etc. and cannott get the sound to stop. It makes the noise for such a short time that they cannot seem to pinpoint it. They claim to have tried so many times that they are no longer willing tio attempt top fix it. Since there seems to be nothing failing. BMW corporation is standing behind their decision.

It is a very annoying sound. It goes away quickly and cannot be duplicated again until the next morning.

Anyone have any ideas?

Thanks

I had a fan belt that would do that on start up for a few seconds almost everytime the car was started. Tighten your belt and see if it goes away.

alternator pulley maybe? I would get a problem like that from my alternator pulley in the winter when its really cold.

-Robert

Squealing noises generally indicate rubber rubbing on metal. So defenetly check all your belts and hoses and make sure nothing is rubbing on them.

Thanks for the quick responses.

Apparently the dealer has checked all of the belts and hoses. Replaced the pully tensioner, twice, among other standard items.

Any other "guesses"?

Thanks

Take it to a different dealership and call BMW NA direct and complain. You might have a case for the Lemon law.

Um, don't park in the garage overnight?

A simple test to see if the noise originates in the belt drive system would be to remove the belts before starting the car in the morning. If that cures the noise, it can be further pinpointed by then installing one belt before starting the next morning.

Has anyone considered that the starter clutch could be faulty?

99% it's your belt. It's either too loose or it's got some glazing on the belt surface, causing it to slip on a pulley and squeal. On you model year I am almost 100% certain that it has a tensioner pulley so if you've had the tensioner replaced (at 10k?? Wierd) then I doubt it's loose. It's prob the belt needs replacing because of glazing. This can happen to a belt regardless of age, I've had to replace brand new belts because of this same problem. All it takes for the belt to slip a little bit once and you have a glazed spot on the belt that will slip when it's damp and squeal until it warms up.

Oh, and don't buy that "belt dressing" crap, that goop you spray on a belt to get it to stop squealing. It's useless and will prob just make things worse. Belts are an easy DIY job BTW.

If they checked the belts then have someone start the car while you listen. It could be your starter if it sounds like its kinda coming from under your intake manifold.

Air pump?

Thats a lot of trouble for 5 seconds of noise a day.

I vote belt.

You stated they replaced the tensioner. Great, which one? there are two. I had the same issue and it was the tensioner for the alternator and power steering. The other tensioner is for the AC. So again check to see which they replaced and ask to replace the one that they did not.
I agree with others here that is is most likely the belt and to be sure removing all belts and starting the car would verify that assumption.
Good luck.

Must be something in my garage! I've had 2 M54 engines (Z3 and present 530i) that did/do the same thing, sounds like belt tensioner squeal first thing in the morning. Dealer could not duplicate on Z3, will be taking 530 in soon for warranteed Inspection II and will discuss it with them then. I suspect that a new belt will cure problem. Let us know what cures yours.