Belt length causing tensioner rattle | Page 2 | Ford Explorer Forums - Serious Explorations

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Belt length causing tensioner rattle

This was super helpful. I had to replace my alternator and also replaced the serp belt. When I was finished the tensioner was clacking like crazy so I replaced it too which helped. A week later it started clacking again in gear. I went back to my parts store and did some research. It turns out they carry this belt from 3 different companies at different price points. Even though they are all for the same car/engine etc they are all different lengths! Crazy! I went with the shortest belt (Also the cheaper option) and the clacking is gone! Thanks, Pontiseve.

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another thanks pontisteve. i went down the tensioner route too but after replacement, still had a rattle. i was SO close to ordering an alternator (the rattle was louder when i pulled more juice, but only at an idle rpm) until i found the pictures you posted of a slack belt and a properly tensioned belt. my belt showed no visible signs of wear but the indicator on the tensioner told the story.

my engine is the v6 ohv with a/c on a 95 - i used a gated k060870.

*IMPORTANT* when you service your belt, especially on pre 98 OHV trucks, I strongly suggest replacing your idler pulley. They also cause subtle noise symptoms before they fail. The pulleys are a failure item and if they are original by this time they are waiting to divorce from the bearing and leave you stranded! It is inexpensive and a 5 minute job.

I've found on most vehicles (not just Exploders!) when it seems the belts are too long and you have to keep getting shorter and shorter belts the problem is a worn out tensioner-but since it's constantly under spring tension there won't be any play just a worn out internal bushing or shaft. Replacing the tensioner assembly, not just the pulley, tightens everything up and also eliminates the "tensioner shake".


Replaced the alternator several times because I was SURE that was what was creating the noise. After reading this (thank you Explorer Forum), found it to be the tensioner rattling, due to incorrect belt length. As previous posters stated, the problem was worse with the A/C on. The tensioner was fine, just at the end of its range. Took trying several different belt lengths before I found the right one. Dayco 5060875 did the trick.

Here's another data point for you...

I just had to replace the belt tensioner on my 98 SOHC (the old one broke). By the time I found out that my son was working on it, he had the job done with the old belt - I forgot to tell him I had a new one. Dang, but I'm one lucky old man.

But we started it up and the new tensioner was chirping whenever it bounced - which was a lot. So we changed the belt and get no chirping. Go figure - eh?

I got the new belt at O'Reilly: MasterPro Belt/Hose - Serpentine Belt Part # K060864 which is listed as 86 7/8 ".

Comparing the two belts, the new belt is a bit shorter and thicker. And the new belt required more strength to pull on the tensioner. With the old belt the tensioner was bouncing right around 8 o'clock, but with the new belt it's almost down to 6 o'clock.


Had the same issue and I taken care then problem with flat head end hammer cut little bit of the tantioner filing point problem solved ;)