View Full Version : Belt Tensioner Oscillating?
GeoffK
08-22-2004, 09:21 PM
I noticed today when the engine was running that the belt tensioner is oscillating back and forth a great deal. I don't think this is normal and wanted to ask if anyone else has noticed this or does you tensioner stay relatively stable? It is moving back and forth such that the arm is moving quite a distance either direction. I am thinking perhaps I have a bent pulley somewhere or something in the AC clutch causing this?
BillyGman
08-23-2004, 12:16 AM
Can it be loose bolts on the tensioner?
FordNut
08-23-2004, 06:23 AM
I have noticed this on some other members' cars. Mine doesn't move at all. Don't know if it's a problem or not.
TripleTransAm
08-23-2004, 06:28 AM
I think it deserves being looked at. I can't remember the exact details, but for some reason I recall having spoken to someone about belts and tensioners and being told this was not normal behaviour. I wish I had more concrete details... all I know is that it was not in relation to anything having to do with Marauders, so it must have been quite a few years back.
The tensioner should be applying a constant tension on the belt, so the fact that this tension is being overcome (and the tensioner bobbing around) is due to some change in the tension of the belt in that area. Whether it's caused by a localized imperfection in the belt itself, or an out-of-round pulley somewhere in the system, that has to be determined. I'd have someone look at it just to be sure... I'm not a big fan of leaving things to vibrate excessively as this causes undue wear on other parts of the system.
David Morton
08-23-2004, 10:48 AM
Three things can cause this "bobbing". In the order of frequency are (in my 10 years as ASE Master Tech experience): #1) Worn belt that has low spots in it, #2) Debris on one or more of the pulleys that makes a high spot; and #3) bent or loose pulley, or one with a bad bearing.
A visual on a running engine will show up #3 & #2 most of the time and if you don't determine the problem is there, just replace the belt.
Oh, and one last thing, do find out and repair this problem. There is a bushing inside the tensioner that is not designed to last very long doing this kind of duty. It will wear out faster if the problem isn't fixed.
Mongoose
08-23-2004, 10:40 PM
My :twocents: goes to the bad tensioner bearing. There was no bushing in mine, just a sealed bearing that went bad. After purchasing and installing a new tensioner, I repaired the original (~$4 for a bearing) and am keeping it for a spare.
Donny Carlson
10-11-2004, 06:41 PM
Fordnut emailed me that he had noticed my tensioner was oscillating, and sure enough, he was right.
Today, Scott over at Team Ford replaced the tensioner under warrantee. Fixed!
Pics of the new tensioner:
http://www.mercurygallery.net/mmnet/data/500/1136DSC01333.JPG
http://www.mercurygallery.net/mmnet/data/500/1136DSC01332.JPG
Smokie
10-11-2004, 07:13 PM
My tensioner does not vibrate, if you are under warranty, take it in for repairs is not normal. If is on your nickel, take the belt off tensioner and spin by hand, listen, rotate by hand slowly, feel for roughness, try flexing pulley to check for bearing play, should be none, check that bracket moves freely, moves without binding when you load against spring. If pulley checks ok, replace belt.
jakdad
10-13-2004, 08:57 AM
Our 01 Sable had a tensioner fail at 32,000 miles. We replaced it and put on a new belt. Saved the old belt for hard times. An interesting side note, the tensioner we bought at O'reilly auto is the same brand (Gates) down to the last detail as the OEM. I guess Gates and Dayco furnish most OEM tensioners.
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