Screeching like Belt Slipping on Startup

[Traian]

I want to solve all the little problems on my car now. A while ago I replaced the main belt and one of the pulleys, after it disintegrated on me. I believe everything was installed and routed correctly, and I tightened up the bolts on the tensioner.

The only difference I noticed was that somehow when it was loose, the tensioner swept out through its motion (its arc) with much more difficulty than when I first untightened it to remove the old belt, when it moved very smoothly. Anyway, now the car makes an awfull screeching noise on startup like a belt slipping, which stops after about 5 seconds and never comes back, until another completely cold starup (ie overnight).

I took it in to a indy BMW shop, they looked it over and told me everything looks okay to them, belt, pulleys, tensioner. They suggested that it might be the AC belt, which does indeed look all cracked and worn. However it seems like too much of a coincidence for this to ahve started right after I replaced the accesory belt. Anyone have any ideas? Thanks!

[Blitzkrieg Bob]

give the belts and pulleys a shot while the motor is running.

[aston_jag_tech]

Its the starter!!!!
I had the same problem, only when engine is very very cold and only lasts a few seconds. The bolts for the starter are 17mm. You need wobble extensions(3/4) and the extensions need to be as long as the block pretty much. Plus a 8,10 and 15..or 13. 30 minutes tops.

[Russell]

May be one or more of the pulleys. Mine were all repaced and noise went away. Now I am starting to get a small period of squeal on the first start after setting several hours. I think it is pulley staring to wear. I have also been told an old tensioner will cause a small amount of slippage.

[winfred]

bingo, it's a worn bearing on one of the rollers most likely, it will get worse till it locks up and tosses the belt

May be one or more of the pulleys.

[Traian]

Thanks for the suggestions. The pulleys felt tight and solid when I replaced the belt, none of them budged. Also the belt feels tight now, and is not worn unusually or anything, after maybe 1000km driving. If it is the tensioner, what should I look for? Also, aston_jag_tech, what did you mean by the starter? Bad starter? That would be bad...

[aston_jag_tech]

Thanks for the suggestions. The pulleys felt tight and solid when I replaced the belt, none of them budged. Also the belt feels tight now, and is not worn unusually or anything, after maybe 1000km driving. If it is the tensioner, what should I look for? Also, aston_jag_tech, what did you mean by the starter? Bad starter? That would be bad...

I had a squeal screech on cold starts after car sat for a long time. Only after the engine started and the starter disengaged. I tried to demisnish it with the old starter but the internal plastic parts were broken and it was pointless to put it back in. But, the starter did its job day in day out, just a really embarssing noise on cold start ups.
I havent found the fault in the starter but my problem was the starter.

You should upload a sound clip of the noise. I would say if your noise is very high pitch squealing that is a lower frequency than I would suspect pulleys and since you just recently had some work done there, check it.

[Traian]

Thanks yes it is a high pitched squeal, but i don't think I have any way to upload the sound? If I remove the belt, can I just check for play in the pulleys and find the problem this way? I also bought a can of belt dressing and will apply it the next time I drive the car (don't have too many chances nowadays).

[Traian]

Thanks Bob, the belt dressing thing worked, no more squeak!! And my windows work too now (unrelated to the belt dressing), man what a day! Now gotta fix that transmission whine....