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+--- Thread: cm870 belt tensioner (/showthread.php?tid=3023)
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cm870 belt tensioner - tree98 - 04-23-2018
Belts been squealing, started at around 1700 rpm and has been gradually starting to squeal at lower and lower rpm's, now it starts around 1400. How tight should the tensioner make the belt? I can turn the fan pulley by hand without hardly trying seems like that's to loose right?
RE: cm870 belt tensioner - Nilao - 04-23-2018
Mine continued to squeal. Once they burnish the surface thgey never stop until you replace the belt. But yes I'd replace the tensioner as well if its over 700k.
RE: cm870 belt tensioner - Brock - 04-23-2018
With belts and tensioners, I found you save a bundle if you go to automotive part stores rather then the oem. I like the continental belts as I've always like the Goodyear gatorback so I go on continental website and find the part numbers for belts and tensioners then bring them to a local auto parts place.
Belt at international $120
Belt at Partsource $30
Tensioner at international $280
Tensioner at Partsource $145
RE: cm870 belt tensioner - Chamberpains - 04-23-2018
I also shop ebay for belts. There are a lot of businesses getting rid of old stock cheap. I picked up original Continental part # belt and a gatorback goodyear belt for $30 free shipping just last month. I also had to find a belt that was 2" shorter because my alternator pulley was size reduced somewhere in its molested life.
With continental part #'s, the first #'s are the # of grooves and ridges across the belt that needs to match your pulley and the 2nd set of #'s is the total length of the belt in millimetres. So if you need a shorter belt just knock off 25 millimeters per inch and search that part number. Although most belt #'s end in 0 so just round off in the safe direction and you should find the length your looking for.
RE: cm870 belt tensioner - tree98 - 04-23-2018
(04-23-2018 )Brock Wrote: With belts and tensioners, I found you save a bundle if you go to automotive part stores rather then the oem. I like the continental belts as I've always like the Goodyear gatorback so I go on continental website and find the part numbers for belts and tensioners then bring them to a local auto parts place.
Belt at international $120
Belt at Partsource $30
Tensioner at international $280
Tensioner at Partsource $145
The tensioner sure looks like a Cummins only part
RE: cm870 belt tensioner - Nilao - 04-23-2018
Nah, I got mine from my local heavy duty Napa. Called Traction. It's a Gates brand tensioner.
RE: cm870 belt tensioner - Signature620 - 04-24-2018
I find that a sufficiently tensioned belt will let you turn the fan by hand 1 way but not the other. With the engine running see if the squeal goes away for a moment if you squirt WD or brake clean spray on it - If it squeals louder for a second then goes away conpletely for a moment it probably just needs a new belt.
RE: cm870 belt tensioner - Rawze - 04-24-2018
(04-24-2018 )Signature620 Wrote: I find that a sufficiently tensioned belt will let you turn the fan by hand 1 way but not the other. With the engine running see if the squeal goes away for a moment if you squirt WD or brake clean spray on it - If it squeals louder for a second then goes away conpletely for a moment it probably just needs a new belt.
I have always used a bit of plain water in a squirt bottle. I would think WD would leave an oily film?.
Anyhow, Many times, squealing belts are also caused by polished pulleys much of the time. After removing the belt, rough the pulleys up with a wire brush to remove buildup in the groves and to remove any polishing. I know of one guy who claimed he could not get his to stop squealing no matter what... New belts, new tensioner, he roughed up the pulleys with a wire brush,.. he eventually resorted to painting his pulleys with a bit of muriatic acid and letting it sit on them for an hour or so, washed it off with plain water, then wire brush again, -- After that, no more squeal.
RE: cm870 belt tensioner - Brock - 04-24-2018
Yeah the tensioner absolutely is not Cummins only, Cummins does not make tensioners. It's usually these guys or similar
http://m.acdelco.com/auto-parts/belts-and-hoses/belt-tensioner-pulley.html