hi everyone,

I have had an issue with my 5 series lately where when i slow down ( belt is slowing down ) i hear a squeal noise that is fairly loud and almost sounds like i am spinning tires around a turn. I replaced the serpentine belt AND the tensioner and the noise is still there !

there is about a quarter inch of play on my serpentine belt, and i was thinking it might need to be tightened more.. but at the same time it took a lot of pressure on the tensioner before i got it to the point that it is at, so i dont want to put much more pressure for fear of breaking something.

Any ideas or help would be great

 

No offense but I think you put the belt on wrong OR you are missing a pulley somewhere. Trust me I've seen it before. Actually i have an AMAZING story where I had changed belts 2 yrs ago and just last month the serpentine belt snapped. I thought I lost a pulley because I had a bearing on the alternator which had no pulley so I attempted to replace it and found NO DIAGRAM with this ghost piece. Dealer didn't sell the tensioner pulley and wanted to convert me to some other hydraulic system. The two tensioner pulleys are the same so I got one from Pep Boys and replaced it. The belt just would not go on. So I looked over a diagram and that pulley did not exist. Why did I replace it? because there was a bearing there to begin with. Keep in mind I changed belts a few years ago and had no problems. So I just took that piece off and replaced the belts like all the other M54 engines I've owned and what every document said. After examining the belt it appears that the bearing that was there put a wearing on the belt for the past two years and ate through part of it....so yeah, weird things can happen.

The first time I changed belts I just degreased/washed the engine and had a squealing for like 500 miles so I changed belts. So that's my story about belts.

 

Could it be pulley bearings? I get a similar sound at a cold start and I'm guessing that's where the sound is coming from.

 

Thanks for the input guys, I'm gonna take the belt off tomorrow and take a closer look to see if i can pin point the issue.

When i first noticed the noise i thought it was just the belt. when my dad and i were trying to put the new belt on, we realized one of the tabs on the tensioner was broken off and there was also a missing rod.






pics comparing the new tensioner to old. we figured that since it was so busted up that HAD to be the issue. i'll have to take a listen tomorrow to see if it might be a specific pulley that is making the noise.

 

when is it making the noise?

Is it possible that it is the ac belt?

Will it make the noise with the main drive belt off?

And yes please check belts after it has been running a couple minutes. If the belt is off a little bit on on pulley it will most likely jump a rib or two off within the first 5 minutes.

 

it is possible that it is the ac belt, im going to try running it without the main belt like you said.

other wise i might just have to bite the bullet and have a local shop check it out. im sure with a lift and the proper tools it should be a fairly easy fix

 

Sounds pretty simple but since your old tensioner was broken, make sure your new tensioner is 'clocked' correctly when it was installed.

 

i took off the main belt, and the noise stopped.. so it must be something with the main belt.

i may sound stupid when i ask this, but what do you mean by clocked?

 

make sure the tang on the new tensioner is placed correctly on the motor. See the pics below for correct positioning.






Tab should be in the 12 o clock position and in the slot

 

awesome, thanks for the pics as well.. im gonna take a look. appreciate the help !