Serpentine Belt broke while driving - new belt won't install!

[Shanestrait]

It is two broken pieces.

You're saying you would remove the entire outer edge?

[abscate]

No, just JB weld the broken pieces back on, working with the glue from the area that does not touch the belt.

[Shanestrait]

So... after a few days of perfectly fine driving,

Today, the dash flickered a couple times while driving. When I got home I popped the hood with car running. Brand new tensioner pulley was moving (not side to side, but back and forth a little).

Is this part bad and do I need to get a new one? Is it not providing enough tension?

[cn90]

I have learned a long time ago that for my BMWs and Volvos, I only use INA tensioner and Conti belt, which are exactly what came from factory.

They fit perfectly, zero issues.

[Shanestrait]

Noted - if I get a new one I will get INA.

Is this indicative or a faulty tensioner or could there be other issues? Didn't notice any obvious issues on the other pulleys.

[Shanestrait]

Pulled belt and checked torque on mount bolts, started again and still happening. It felt like there was sufficient tension on it when I held it when removing/installing belt. What a nightmare of a job this has been.

[RickHaleParker]

Keep your cheap tensioner at your own risk. My advice is, never go cheap on mission critical components. The risk-reward ratio is unfavorable.

[Shanestrait]

I've ordered an INA tensioner. Hopefully it holds up.

I'm quickly learning to not go the quick easy route on these parts.

[RickHaleParker]

If you comb through the forums, you will find cases when the Serpentine belt snapped or came off and took out the timing belt.

[SuperHerman]

The tensioner has the ability to move back and forth. That is what the spring is for - to keep tension. I would look else where and eliminate something else causing the movement, which the spring in the tensioner is reacting to. As mentioned in my earlier post, some other pulley or the harmonic balancer (rubber in this may have gotten damaged) may have been damaged and has a "short and a long side". This "short and long side" changes each revolution of the offending component - as it gets long the tensioner spring applies more pressure, as it goes short it applies less -- so you see the tensioner moving back and forth.

I had a harmonic balancer fail on my BMW, which was bought with a damaged engine. A new used engine was sourced from a front end wreck and my shop installed it. The original engine damage was caused by a serpentine belt that snapped and sucked up into timing belt and caused a ton of damage - ruining the engine (like Rick mentions). When it was all put together I noticed exactly what you described. I changed out the tensioner myself and asked the shop about the harmonic balancer. It happened that they used the original one, rather than one from the donor engine. They swapped it out and no more wobble.

With proper light and the engine running go through all the pulleys mentioned earlier and the harmonic balancer looking for wobble. Have some one bring up the RPMs to 1500 and look for any changes. Exclude all possibilities. Yes, it could be the tensioner spring on the new unit you purchased is too weak and causes the wobble, but excluding everything else makes sense. It could also be the alternator is failing - if that is what the engine light showed. Do you have any squealing from the belt?