[LocDawgg]

So the other day while driving i noticed my serpentine belt came off. I knew because the A/C stopped, Power steering didn't work, and the battery light came on.

I took the belt off and didn't notice any wear or tear so i decided to reuse it. Still didn't know why it came off in the first place. But i put the belt back on via unloading the tensioner. Afterwards i go to start the car and noticed that the belt is still running but it looks like it is about to fall off the tensioner.

I tried several times to put it back on, which it is perfectly on every time i do so, but after the car starts up and the belt starts to run it slips almost off. I can actually pull it off with my own hands when the car is off.

Attached is a picture. Let me know what you guys think the problem might be. Do i need a new belt? Or maybe a new tensioner?

EDIT: Also i noticed other pictures of tensioners and it seems that my tensioner is missing the actual bolt. The bolt is suppose to be blue and my tensioner doesnt have a bolt at all i think, it just looks like its hung on to something white.

[dc5pat]

Seems like the bolt head broke off from the tensioner. That's why your belt keeps sliding off. Had a bad tensioner on my car but my belt wasn't that off like yours. Just replace all of it at the same time. tensioner, belt, idler pulley, bolt. I got all mine from RM european for about $100.

[Efthreeoh]

Originally Posted by pacman2700

Seems like the bolt head broke off from the tensioner. That's why your belt keeps sliding off. Had a bad tensioner on my car but my belt wasn't that off like yours. Just replace all of it at the same time. tensioner, belt, idler pulley, bolt. I got all mine from RM european for about $100.

This is correct. The tensioner mounting bolt broke and the tensioner is only hanging on by the pin. You need to fix this before you drive the car again.

[LocDawgg]

Originally Posted by pacman2700

Seems like the bolt head broke off from the tensioner. That's why your belt keeps sliding off. Had a bad tensioner on my car but my belt wasn't that off like yours. Just replace all of it at the same time. tensioner, belt, idler pulley, bolt. I got all mine from RM european for about $100.

Do you know if RM European carries genuine BMW parts? Or are they aftermarket?

[Efthreeoh]

Originally Posted by LocDawgg

Do you know if RM European carries genuine BMW parts? Or are they aftermarket?

LocDawgg, just get a new bolt and re-install everything. The belt looks good, but if it is damaged somewhere from slipping off, then replace it. It is about $30. Unless the tensioner is broken, or the bearing is bad, leave it be.

Spend the money on a set of easy-outs, because you're going to need one to get the bolt shank out.

[LocDawgg]

Originally Posted by Efthreeoh

LocDawgg, just get a new bolt and re-install everything. The belt looks good, but if it is damaged somewhere from slipping off, then replace it. It is about $30. Unless the tensioner is broken, or the bearing is bad, leave it be.

Spend the money on a set of easy-outs, because you're going to need one to get the bolt shank out.

I actually got the bolt out with some needle noses. So you think the tensioner should be still good to use?

[kfrazie1]

Originally Posted by LocDawgg

Do you know if RM European carries genuine BMW parts? Or are they aftermarket?

I ordered the same parts from them. When you look at the part it will let you know if its oem. Replace idler pulleys while you are replacing tensioner.

[LocDawgg]

Originally Posted by kfrazie1

I ordered the same parts from them. When you look at the part it will let you know if its oem. Replace idler pulleys while you are replacing tensioner.

So is it OEM? lol

[kfrazie1]

Yes. Some "OEM" parts are actually made by other companies. I think the belt is contitech but its the OEM part BMW used.

[Efthreeoh]

Originally Posted by LocDawgg

I actually got the bolt out with some needle noses. So you think the tensioner should be still good to use?

If it doesn't make noise and the bearing isn't rough when you spin the pulley (it should have some drag to it), I don't see why it would be bad. The only other part is the spring. If you can, mount it in a bench vice and see how strong the spring tension is and how well it moves through the tension of the spring. If it doesn't stick, then I'd continue to use it.

[Chriztofor]

Originally Posted by pacman2700

Seems like the bolt head broke off from the tensioner. That's why your belt keeps sliding off. Had a bad tensioner on my car but my belt wasn't that off like yours. Just replace all of it at the same time. tensioner, belt, idler pulley, bolt. I got all mine from RM european for about $100.

Originally Posted by Efthreeoh

If it doesn't make noise and the bearing isn't rough when you spin the pulley (it should have some drag to it), I don't see why it would be bad. The only other part is the spring. If you can, mount it in a bench vice and see how strong the spring tension is and how well it moves through the tension of the spring. If it doesn't stick, then I'd continue to use it.

Whether the tensioner is bad or not is irrelevant. Might as well replace it if the bolt broke and you have the tensioner in your hand.

[LocDawgg]

Originally Posted by Chriztofor

Whether the tensioner is bad or not is irrelevant. Might as well replace it if the bolt broke and you have the tensioner in your hand.

I replaced only the bolt and cleaned off the tensioner. It was still working fine. Car runs good now no problems

[Chriztofor]

Originally Posted by LocDawgg

I replaced only the bolt and cleaned off the tensioner. It was still working fine. Car runs good now no problems

For the next ------ miles. But hey, you might get lucky.

[LocDawgg]

Originally Posted by Chriztofor

For the next ------ miles. But hey, you might get lucky.

Yeah i might, and if it does fail then i will just replace it. Its not very difficult to do and would take less then 10 mins or so.