Tensioner makes a knocking sound, common problem? what is the fix?

[sakudog]

My tensioner is occasionally making a knocking sound, I've verified it is the tensioner.

Is this a common problem? The tensioner itself seems to be strong enough to tension the belt but the pulley is noisy, can you just replace the pulley?

Who makes a replacement unit other than NOS4GN who wants nearly $400 for what should cost $90 max!

 

[Royal-T-Ltd]

dunno if its the fix for you. but you can replace just the bearing in the pulley or the whole pulley itself, if thats the problem. Both are relatively cheap fixes.

 

[87chrisss]

Yes it's very common for the tensioner's to be noisy. Mine also does it occasionally. On my other T-type it was so loud + vigilante multidisk converter with all the rattling it litterally sounded like my motor was gone, but i knew what it was..

 

[sakudog]

I did see that RockAuto carried a few replacement pulleys by Dayco & ACdelco.

http://www.rockauto.com/catalog/moreinfo.php?pk=1332944
http://www.rockauto.com/catalog/moreinfo.php?pk=347137

Has anyone replace the tensioner pulley on these cars before? I'm guessing you need to pop the bolt with a impact to loosen it? Is it anything goofy like reverse threaded etc?

 

[SHADOWII]

I purchased a new pulley w/bearing, a few years ago at advance auto for $15.00

 

[sakudog]

Cool, do you remember the install procedure?

Does the tensioner pulley bolt come out with hand tool mounted on the engine or do you need to remove it?

 

[Royal-T-Ltd]

you can use hand tools...nothing crazy or special.... just reinstalled mine a couple of weeks ago

 

[sakudog]

Ok cool, well then I guess I'll pick up a replacement pulley locally and slap it in tonight.

 

[coach]

Mine sounds like a rod is gone but only when the rpm drops to about 800-900. It's done it for years, so I know the rods are good. I hope my new tensioner on my new engine doesn't do this.

 

[sakudog]

Actually, thats EXACTLY what I thought it was!!!!

 

[broke]

Mine seemed to make alot of noise and it turned out to be alt bearing goin out. Replaced the alternator and the belt and its smoother than ever.

 

[GullsGN]

Mine sounds like a rod is gone but only when the rpm drops to about 800-900. It's done it for years, so I know the rods are good. I hope my new tensioner on my new engine doesn't do this.

Hmmm, that brings to mind a symptom that took me 10 years to find. It was a knock at low RPM, like idle with the AC on, and it wasn't the pulley. There is a bolt behind the AC compressor for the mounting bracket into the block. This bolt had loosened and backed out. Just thought I would throw this out there for anyone experiencing an unexplained low RPM knock at the front of their motor. Hope it helps someone.

 

[Slow91z]

When they knock usually the belt is a shade to short or a shade to long...the tensoner moves as the motor runs and if it's close to the limit of travel either direction it knocks against the stop.

Watch it while running and the knock will be timed with the movement.

 

[gnmaster2004]

Hes right, sounds like a streeched belt, seen it a dozen times

 

[coach]

I have replaced the pulley and the belt. I never tried to tighten the bolt. You can see the tensioner moving to the sound of the knock. Im pulling this engine soon. I will check the bracket and see if its loose. Its held to the front of the head with 3 bolts.

 

[bison]

what length belt are you guys using?

 

[coach]

what length belt are you guys using?

Well you can't see my arms right now, but it's about this big_____________!!! Haha
I'd have to go look

 

[sakudog]

Bison:

Last night when I picked up the new pulley I also grabbed a fresh belt and installed both at the same time, the knocking sound is gone as far as I can tell but the tensioner seems to move more than what I've seen in newer cars is it possible the tensioner arm spring is just worn out?

The belt I'm using is here

http://www.autozone.com/autozone/pa..._/N-iidqmZapsy5?itemIdentifier=10262_0_17408_
Effective length is 63.98"

The pulley I put on:

http://www.autozone.com/autozone/pa...8gd4q?itemIdentifier=634070&_requestid=397302

Again, everything seems to be working fine and the knocking sound is gone....the belt I removed was very old with small cracks all in it...

 

[bison]

The belt that works almost every time is the 635. Every now and then a 630 will go on. The stock replacement is 640 and 99 times out of 100 it will be too long after a short run time.

 

[sakudog]

Bison, dang well I appreciate the knowledge!

Part Number: 640K6
Weight: 0.35 lbs
Warranty: 1 YR
Notes: Multiple accessory
Belt Construction: K-Section
Belt Material: EPDM
Belt Rib Count: 6
Effective Length (in): 63.98
Effective Length (mm): 1625.092