quiet belt for 91 F150

eljefino

eljefino

Joined
Jun 15, 2003
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Loaded 351w with AC, PS, smog pump. Size 935K6.

Belt chirps. Is a brand new Dayco. Tensioner is also a new Dayco.

Sprayed water on it, it stopped, so it's not an accessory bearing. Chirping comes from alt/ tensioner area up top but those pulleys are tight and spin quietly. Alignment looks good but some net searching shows these 91 F150s were commonly noisy.

My chirping also quiets down when I'm cranking the steering back and forth. PS reservoir full.

Looked for a Goodyear Gatorback/ Conti Elite in this size but did not find.

Ideas for a quiet belt?
 
The part number is 4060935, but they were discontinued a few years ago. However, the new belts Conti replaced them with are no problem at all. Conti didn't change the part numbers when switching from the Elite/Gatorback to the OET Series :sneaky:

Maybe this one is the right belt, but they used a stock image, so it is still possible that they could send you a OE Technology series (new straight belt). Contact the seller to confirm :cautious:
 
Dust (yes, from the ground) or baby powder usually fixes a squeaky belt in my experience
 
Never had this problem on my '90 351.

I don't think it's gonna help but you can yank the smog pump and run a belt 2" shorter. No, it doesn't "burn up your cat."
 
Will try a Bando belt, if that doesn't work, then I'll try some other ideas in this thread.

Going over my receipts, I got a Dayco Drive-Rite, probably the worst of the worst.
 
Put the Bando belt on, just the regular duty one. Quiet as a mouse. The tensioner judder is gone, too. Think the Dayco Drive-Rite (which I hate, LOL) had some sort of defect, maybe in how deep they cut the grooves, that changed its effective length as it went around the accessories. Anyway good riddance to bad news.
 
eljefino said:
Put the Bando belt on, just the regular duty one. Quiet as a mouse. The tensioner judder is gone, too. Think the Dayco Drive-Rite (which I hate, LOL) had some sort of defect, maybe in how deep they cut the grooves, that changed its effective length as it went around the accessories. Anyway good riddance to bad news.
Click to expand...
I'm sure you know this but the tensioner has an arrow with acceptable range of operation. Really only an issue if you start changing belt lengths.

I ran an externally regulated 100A Taurus alt, van Sag p/s pump, and had a York driven off a custom pulley from the alt. And no air pump of course. Belt routing changed considerably around '93 (I don't think it was '92 despite the front clip revision in '92)
 
While we're at it the Dayco tensioner has a little pin that meets a cavity on the aluminum mounting bracket, and on this truck it was misaligned. Correct P/N per "everybody." I hogged out the hole by about 1/16" and it fits fine. The Drive-Rite belt seemed "very very" tight while the Bando is "correctly" tight, and/or I finally came up with a good system for getting it on there with all my time spent fiddling.

Seeing how Ford was just switching over to serpentine belts in 1991, I figure this first-generation setup was engineered to be tight. It does have to support ~5 hp for the fan.

Truck still has its air pump, the whole thing is in "old man trim." Came with a suction cup compass and those deer whistles on the front bumper. :ROFLMAO:
 
Serp was definitely common by '87. I'm not sure if the first EFI 302s in '85 trucks used a single belt? They definitely had an additional mess of spaghetti for emissions stuff running in to the filter housing and intake tube that slowly got cleaned up over the years.

It's pretty bomber -- I haven't really seen many belt issues on the brick nose trucks.
 
Not that it helps OP, but large case Taurus alt and York OBA (I wish all my trucks had engine driven, infinite OBA)
20231101_170203.jpg
 
eljefino said:
Loaded 351w with AC, PS, smog pump. Size 935K6.

Belt chirps. Is a brand new Dayco. Tensioner is also a new Dayco.

Sprayed water on it, it stopped, so it's not an accessory bearing. Chirping comes from alt/ tensioner area up top but those pulleys are tight and spin quietly. Alignment looks good but some net searching shows these 91 F150s were commonly noisy.

My chirping also quiets down when I'm cranking the steering back and forth. PS reservoir full.

Looked for a Goodyear Gatorback/ Conti Elite in this size but did not find.

Ideas for a quiet belt?
Click to expand...
Does the replacement Dayco belt part number have a "DR" suffix? This is their "economy" replacement belt.

The only difference is I can find between the two tiers, according to the description in the RA catalog, is there's no mention of the economy belt meeting SAE J1459 and SAE J2432 specifications (dimensioning and testing methods).

Both belts are probably the same. The economy one just hasn't gone thru a QC or SAE cert process. 🤷‍♂️
 
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Which tier of Dayco? They make a lower end, but also a higher end with aramid fibers on the V-pulley side that helps to keep them quiet.
 
I have had my share early on with belt noise on my 87 F150. Only two brands have been quiet. Dayco Polycog and Goodyear. Goodyear is gone but I have been running the same Dayco belt noise and crack free for atleast 15 years now. Gates and Motorcraft have been noisy.
 
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eljefino said:
Put the Bando belt on, just the regular duty one. Quiet as a mouse. The tensioner judder is gone, too. Think the Dayco Drive-Rite (which I hate, LOL) had some sort of defect, maybe in how deep they cut the grooves, that changed its effective length as it went around the accessories. Anyway good riddance to bad news.
Click to expand...
Sad to hear that the day I was so bad. What is coo on dayco and Bando?
 
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