belt tensioner assembly
 

I'm kind of new to Ford's but now have an old F-1 with a 302 Mustang HO '85 engine. Trouble with the serpentine belt & alternator and wondering if the heavy belt tensioner assy could be the cause?? Mine moves with some force but wondering if they should move freely??

The tensioner is spring loaded to enable it to keep the proper tension on the drive belt. If you look real closely, you will see an arrow and a gauge on the tensioner. As long as the arrow is within the guide marks, you have the correct length belt and belt tension. The tensioner will go bad as well as the idler pulley on it. What type of problems are you having?

Thanks for the reply! I've had 2 alternator replacements due to front bearing failures, replaced the tensioner assembly totally & a new belt but still have belt contact just under the tensioner. Little rubber particles all over! I don't get it as the replacement parts are same as what ran fine for months!!!

Are you sure the replacement alternators were the exact match as the OEM? Was the same pulley used?

Remans are usually thrown together from a common pile of parts, i.e. thay pay little attention to what the exact fit was on any one car. So this problem was present before replacing the tensioner?

I'm not sure what you mean... is the belt under the tensioner touching itself where it goes aroundthe W/P? If this is the case, try a slightly shorter belt.

Yes it is & I tried 1 size shorter but I can't even get it on its so tight! I don't get it as the pulley is the one off the last alternator I think there's only one correct way to wind the belt. It goes from the PS pump under the tensioner pulley to the alternator back over the wp pulley & down & around the crank pulley. Its like the tensioner is too strong but the old one that worked for a year does the same!

Check your belt installation, on some models there is more than one way to route the belt. You can usually tell the correct orientation by the way the belt rides on the individual pulleys, ribbed side always rides a ribbed pulley. Smooth pulleys always see the smooth backside of the belt.

Worth a look see. ;)

Bringing this back up for closure. I'd like to think that when one posts a problem, you should also provide closure so that the solution is open to everyone, even if its simplistic!! So, the belt started rubbing on itself due to a loose alt. pulley . It rounded out the hole enough to let the belt touch itself. So, I got another pulley & went through a belt trial fit ... then I found out that the pulley I'd bought, despite being same diameter across the outer, is about 3/8" under when you mike the inside where the grooves are!! Turns out that 4 cylinder pulleys are under enough to let the belt touch itself while the proper 5.0 liter Mustang pulley gives you JUST enough room when the tensioner comes down. Serpentines are not adjustable with slide grooves so the pulley size is critical! Looking back its easy but like so many things in the sport when you start crossing up stuff for your hot rod , its NOT!!

:thumbup:

Thanx For The Post!

Appreciate your sharing what you found...