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Discussion Starter · #1 ·
Hi everyone,

I'm looking for some serious advise, help and direction here. Back in May I had the serpentine belt, tensioner and idler pulleys replaced on my 2008 e92 335i. When the upper idler pulley was being replaced it was over tighten and stripped the threads of the aluminum block. The hole was then drilled out, tapped and replaced with new threads.

The belt was then put on and everything was fine for about 2 months until mid-july when the belt started squealing. I didn't think that the belt would go bad that fast so I replaced it with a genuine BMW belt in early August. When the new belt was put on the car ran perfectly!..for about another 2 months.

Recently the water pump failed at 65k and I used this opportunity to replace the pump, belt (Dayco this time) and upper pulley...again. The belt was fine for a few DAYS this time. Now it makes a light squealing for about 5-10 minutes until the belt warms up.

I'm thinking that when the hole was drilled and tapped in the block that it might not have been 100% straight and is causing the pulley to sit on a slight angle and is now burning through belts (4 in approximately 6 months).

I'm lost with what to do right now, but I need to have this repaired. If anyone can provide some input or knows someone in the Northern NJ area who would be willing to help out and repair this issue...that would be awesome!
 

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JJ, if a pulley is misaligned or at an angle, especially the tensioner pulley, the belt will show severe edge wear. You don't mention any observed wear at all. Most any indy shop should be able to resolve your problem.
 

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did you redrill and tap the hole of did someone else do it? if it was someone else I would go back to them

If you did it, how did you drill out the hole and tap it and still use the same bolt?
you should have drilled it out, tapped it and then installed something Like Keenserts, or Helicoils
both are threaded inserts that will bring the over sized hole back to original size
 

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Discussion Starter · #4 ·
did you redrill and tap the hole of did someone else do it? if it was someone else I would go back to them

If you did it, how did you drill out the hole and tap it and still use the same bolt?
you should have drilled it out, tapped it and then installed something Like Keenserts, or Helicoils
both are threaded inserts that will bring the over sized hole back to original size
I've drilled and tapped the hole using the PowerCoil kit. Like DSXMachina said, there might be an angle causing the belt to slip towards the edge. When I replaced the last belt I didn't notice any wear.

I've had 1 indy shop turn me down because they didn't want to touch it. Is this something that could be repaired? Could a skilled mechanic realign the hole and replace the threads?
 

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I've drilled and tapped the hole using the PowerCoil kit. Like DSXMachina said, there might be an angle causing the belt to slip towards the edge. When I replaced the last belt I didn't notice any wear.

I've had 1 indy shop turn me down because they didn't want to touch it. Is this something that could be repaired? Could a skilled mechanic realign the hole and replace the threads?
I don't think your tensioner is crooked. Even if you did drill the hole crooked when you were installing the insert the back of the tensioner is a broad flat surface. It would tend to sit flat when you torqued down the bolt. Don't jump to conclusions.
You don't even know for sure yet that belt misalignment is the cause of the squeal. There could be other reasons. Oil can get on the belt and it doesn't take much. The belt may be slipping due to excessive load from a binding component. This needs a professional evaluation. At my shop we'd start with a visual exam, followed by belt removal and hand spinning of all the rotating parts.

[We never discussed the possibility that the tensioner itself is shot. Poor tension = slipping belt.]
 

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Discussion Starter · #6 ·
I don't think your tensioner is crooked. Even if you did drill the hole crooked when you were installing the insert the back of the tensioner is a broad flat surface. It would tend to sit flat when you torqued down the bolt. Don't jump to conclusions.
You don't even know for sure yet that belt misalignment is the cause of the squeal. There could be other reasons. Oil can get on the belt and it doesn't take much. The belt may be slipping due to excessive load from a binding component. This needs a professional evaluation. At my shop we'd start with a visual exam, followed by belt removal and hand spinning of all the rotating parts.

[We never discussed the possibility that the tensioner itself is shot. Poor tension = slipping belt.]
The tensioner was replaced in May and then again in July because I thought that may have been the issue. The tensioner is not where the threads were stripped. It was the upper idler pulley right behind the intake pipe.

Could it be possible that the belt routing is incorrect? My belt has been routed following the diagram below.

 

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The tensioner was replaced in May and then again in July because I thought that may have been the issue. The tensioner is not where the threads were stripped. It was the upper idler pulley right behind the intake pipe.

Could it be possible that the belt routing is incorrect? My belt has been routed following the diagram below.

That is the correct routing. Visually sight along the edge of the belt, does everything look to be in line? Are the ribs of the belt all sitting in pulley grooves? Remove the belt and spin everything by hand (except of course the crank pulley). Everything should spin smoothly with no looseness or vibration or gritty feel.

Something to try: Shut off all accessories. Turn off the engine and leave your lights on for five minutes. Start the engine. Any squeal? Turn on the AC. Any squeal? Turn your steering wheel all the way to the lock in either direction. Any squeal?
 

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I agree with DSX that maybe another component, such as alternator or condenser, may be the culprit.

I've heard many good things about Shade Tree in Morristown, NJ. They work on a lot of Euro makes.
 

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Discussion Starter · #9 ·
I agree with DSX that maybe another component, such as alternator or condenser, may be the culprit.

I've heard many good things about Shade Tree in Morristown, NJ. They work on a lot of Euro makes.
I made an appointment to have Shade Tree look it over. They're less than 15 minutes from me. I appreciate your input on a good garage!
 
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