Fox T-Bird/Cougar Forums

Technical => Engine Tech => Topic started by: cougarXLS on December 15, 2007, 05:57:02 PM

Title: Automatic Tensioner... Automatic Problems?
Post by: cougarXLS on December 15, 2007, 05:57:02 PM
Okay,
For those of you who have been following my work with Salt... here is what I believe to be either THE problem, or yet just ANOTHER problem.
I replaced my alternator and installed a new serpentine belt.

I started the car... she fires and then stalls.
Okay, so I fire her again... and keep my foot on the gas pedal.  She runs, doesn't stall.  I then here a 'grinding' from under the hood, I let go of the gas pedal (she stalls, of course, we knew this already).
I inspect under the hood, and find that my new serpentine belt has, literally, 'jumped' that gadget called an "Automatic Belt Tensioner".

The alignment of the serpentine belt is perfect with the crankcase, the alternator, smog pump, water pump, power sterring pump, etc.  This is on the V6 EFI configuration.  The belt, however, is NOT perfect with the automatic tensioner.  The belt seems to want to ride on the 'inner-edge' of the pully on the auto-tensioner.

Please DO NOT ask me to check error codes, as there are NONE.  The breakout box suggests the entire 60-pin EEC-IC computer/wiring harness are fine, so does my own visual inspection.

I also know that NO pully is siezed.  They all spin by hand.

Does anyone know why my belt is jumping the tensioner??  Could the tensioner be dying??  The NEW belt is IDENTICAL to it's predecessor.  ANY ideas ANYONE???
Title: Automatic Tensioner... Automatic Problems?
Post by: SLEEPER T-BIRD 87 on December 15, 2007, 06:03:14 PM
does the tensioner spring back ?
Title: Automatic Tensioner... Automatic Problems?
Post by: *MAYHEM* on December 15, 2007, 06:59:39 PM
Sounds to me like the tensioner is shot/has gone eccentric and needs to be replaced.
Title: Automatic Tensioner... Automatic Problems?
Post by: cougarXLS on December 16, 2007, 01:29:29 PM
Quote from: SLEEPER T-BIRD 87;192943
does the tensioner spring back ?


If you're referring to the ability to move the tensioner (i.e. to install / remove the belt); that seems to be fine.  I can rotate it and it will hold it's place.

Basically, here's my problem.  From a visual inspection the tensioner appears fine, and as far as the mechanical operation goes, well, it SEEMS fine.  Why does the belt jump?


You could be right, I may just need a new tensioner, but the price (from NAPA in CDN) is about $120.  I'd like to be sure the tensioner is the culprit before I replace it, but I am kinda out of ideas.
Title: Automatic Tensioner... Automatic Problems?
Post by: TurboCoupe50 on December 17, 2007, 01:41:17 PM
If your tensioner is chattering and causing the belt to jump, possibly you have other issues... A tight/binding water pump, smog pump, etc can cause this...
Title: Automatic Tensioner... Automatic Problems?
Post by: Beau on December 17, 2007, 05:43:40 PM
Just out of curiosity, are any of the pulleys bent or dinged along the front edges?

X2 on the water and smog pumps, as well

Also, if you have another tensioner from another car that you can "borrow", see if that is the source of the problem, I did have one fail on me one time, and it would not keep a belt on.
Title: Automatic Tensioner... Automatic Problems?
Post by: cougarXLS on December 18, 2007, 12:32:32 PM
I will try pulling the tensioner from Pepper (the 5.0 Bird) and install it on Salt (the 3.8 Bird).  Will give it a go.

All pulley's can move freely hand and are in great shape, no nicks, dings or bends.

So, I guess, it could be the actual tensioner, I'll let you know when I 'swap'.
Title: Automatic Tensioner... Automatic Problems?
Post by: cougarXLS on February 08, 2008, 05:07:19 PM
Time for an update...
So, I did the swap... or at least tried.  The two belt tensioners are not interchangeable.