Hello guys...


I am stuck with trying to figure out why my belt tensioner rattles...


Before I start here is what I have replaced:


belt, tensioner (3), new AC compressor two years ago, and tensioner mount from junkyard


I have tried a new NAPA tensioner, a used one and a junkyard one, and an ebay special - all with the same results.


It has been doing this for over a year now.


The rattle only happens when I have the AC on. Without the AC, the tensioner seems fine and looks like it is vibrating just such a little bit...and no different as my old Lightning and my present Hemi Jeep.


When the AC is on it rattles bad until you reach a consistent RPM. Then it goes away.


It has been one of those things that I have tried to forget, but lately since we have been traveling, we have been using the AC a lot and I hear the rattle a lot!


I have heard of slugging (overcharged AC) can do this in GMs - but the guy I had do my AC was a real pro. It has been flawless for two years. The only thing is I do have front and rear air and my compressor cycles every 20-30 seconds or so. That would indicated low Freon, so that would rule out slugging...I would think.


I do have a little whine from my PS pump, but I don't think is enough to cause the rattling of the tensioner. It is moving back and forth about 1/2 inch when it does rattle.


I do want to add that I have run the van for 5000 miles in the past few weeks with AC on and have had no issues to other parts or systems...


Any ideas??? Need a video?


thanks!

 

By rattle do you mean an actual noise or just that it moves back and forth rapidly?

 

both...

 

In that case it can be any one of the other pulleys. Turning on the A/C increases the load on the belt and in turn effects the tensioner. It could also be the belt itself is too long. When the A/C is on check the wear indicator stops on the tensioner and see it they're hitting each other.

 

I would buy another belt and consider getting another tensioner too. I've been through this before and the problem boiled down to the manufacturer producing tensioners that could not tension the belt enough. This led to the tensioner moving around a lot and this would weaken the belt.
I've also had VW diesels that would absolutely kill anything but the best belts. They had 100 amps of draw on the alternator for 2 minutes every time they were started.
Steve

 

thanks Ill check those out and report back.

 

here is a video...


as you can see, without AC it is 100% fine...turn it on and it rattles. It sounds like the rear pin on the back of the tensioner itself is what is causing it.


You can see if you look closely the belt vibrating a little...maybe it is stretched out?


Let me know what you think..


https://goo.gl/photos/aKDSFMY8Bq6gz6qg8

 

I would go over it with a stethoscope to see what it is. Or wait until it gets worse and more obvious.
Steve

 

Well I just ended up replacing everything - tensioner, idler pully and belt. It sounds good now.

I swear - parts - are - junk - now...

I guess I should expect to change these every year now

 

Well I still have a tick off the start. At least it is gone with the AC on...