Drive belt tensioner noise

[pepehuertars]

The tensioner on my ohv uses what they call the “v tab”.

View attachment 166224

That's right. On my 96 ex OHV, the OE one started to rattle a couple of months ago. I ordered a doorman brand tensioner, It was the same design but the "spring" inside the tensioner was a cheaper construction steel spring or something like that. Ended buying a new Motocraft tensioner that works like the original one.

 

[swshawaii]

ANY parts from Dorman/Help! is a last resort for me. Unless it can't be sourced anywhere else I'll gladly pay Ford's MSRP from my local dealer if I have to. Had fitment or quality control issues with 9 of the 10 Dorman parts I've tried and removed.

 

[CDW6212R]

Replace all of the idler pulleys at the same time when you do a tensioner, or other pulley, or belt with lots of miles.

The belts and pulleys are not identical on all SOHC 4.0's, I had to swap pulleys on my 99 the first time using an aftermarket alternator. That pulley was slightly different, and the two possible OEM belts weren't fitting well, so I changed the top idler pulley, slightly bigger I recall. So it's easy to adjust belt length needed by altering the top idler pulley, if needed.

BTW, consider re-greasing the idler pulley bearings too, the online video/youtube describes poor new grease in them. It's easy to remove the side bearing covers, and install quality grease(white lithium etc) into them, or inject if the covers don't want to come off. Evidently the low end suppliers(China sources, Dorman etc), have people barely putting any grease into the bearings, so they often fail in just a few short years.

 

[koda2000]

The tensioner should have an index cast into it on the part w/out the pulley and a pointer on the part with the pulley. When the engine is running the tensioner pulley will bounce around a little bit (this is normal) but if the belt is a little too long, or a little too short, the tensioner will hit it's stop and make noise. The pointer will indicate if the belt is too long/short. Normally the pointer should run somewhere in the middle of the index. Many belt manufacturers indicate the specifics about their belts in their part number. That Makes them easy to decipher. For example, 865K6 would indicate a 6-rib, 86.5" long belt. If you find your current belt is causing your tensioner to bounce against its stop look for a belt that is slightly shorter, say 862K6 or 863K6. Or you can look for a larger idler pulley which would accomplish the same thing. The tensioner itself rarely if ever makes noise and if the pulley goes bad you can just purchase a replacement pulley, which will probably be plastic because it has shoulders to keep the belt in place.

Sounds like you have quite a collection of tensions now.

 

[239]

The tensioner was making a slight amount of noise when new so that leads me to believe the belt is too long. I’ll try to find an 88” belt since mine is 88.25”. The noise is terrible now so I’m guessing the belt has loosened.

I see an 880K6 on so I might try that.

 

[koda2000]

The tensioner was making a slight amount of noise when new so that leads me to believe the belt is too long. I’ll try to find an 86” belt. The noise is terrible now so I’m guessing the belt has loosened.

I see an 860K6 on advance so I might try that.

Serpentine belts don't really stretch much w/age as compared to old-style V-belts, but If you at max with a new belt I suppose it wouldn't take much wear to make the tensioner start to clunk on its stop.

Were you able to see the index marks on the tensioner?

 

[239]

Serpentine belts don't really stretch much w/age as compared to old-style V-belts, but If you at max with a new belt I suppose it wouldn't take much wear to make the tensioner start to clunk on its stop.

Were you able to see the index marks on the tensioner?

Unfortunately I can’t locate it but I’ll look again tonight.

 

[koda2000]

The photo below is of a different tensioner, but it was the only one I could find that showed an example of the index marks.

Note the 3 lines cast into the spring housing and on the pulley arm. That's what your looking for. If/when you locate them you want to watch them with the engine running to see how they line up.

In any event, I think your belt is probably too long as there's really not much in a tensioner to make noise other than it hitting its stops.

 

[239]

The photo below is of a different tensioner, but it was the only one I could find that showed an example of the index marks.

Note the 3 lines cast into the spring housing and on the pulley arm. That's what your looking for. If/when you locate them you want to watch them with the engine running to see how they line up.

In any event, I think your belt is probably too long as there's really not much in a tensioner to make noise other than it hitting its stops.

I saw two lines on one halve that are about an inch apart. But the alternator bracket blocks the view of the other half where the indicator line would be. I may just try an 88” belt if it doesn’t damage anything. I’m not sure if it will since it’s only a .25” difference.

 

[koda2000]

@239 - Using a slightly shorter belt will not hurt anything. If it's too short you wont be able to get it on. Something slightly shorter than what you have now will probably get rid of you noise. You might even be able to go a little shorter, but as long as the noise goes away (and it stays quite) you're good. If it works write the belt number down somewhere for future reference.

 

[239]

@239 - Using a slightly shorter belt will not hurt anything. If it's too short you wont be able to get it on. Something slightly shorter than what you have now will probably get rid of you noise. You might even be able to go a little shorter, but as long as the noise goes away (and it stays quite) you're good. If it works write the belt number down somewhere for future reference.

I’ll definitely post a separate thread and tag it accordingly. I can see the tensioner move back and forth quite a bit, so it looks like the internal spring is failing. I’ll post a thread with the results when I solve the issue.

 

[koda2000]

I’ll definitely post a separate thread and tag it accordingly. I can see the tensioner move back and forth quite a bit, so it looks like the internal spring is failing. I’ll post a thread with the results when I solve the issue.

As I said earlier, the movement is normal. As long as it doesn't hit it's stops its okay. If the movement is excessive it's not the fault of the tensioner. Another pulley in the system may have excessive run out.

 

[CDW6212R]

My 99 SOHC had a bad first tensioner. It was new and I got it replaced before driving the truck the first time. I think it came from Autozone but I don't recall the brand. I've tried to only buy Ford tensioners since then.

 

[koda2000]

My 99 SOHC had a bad first tensioner. It was new and I got it replaced before driving the truck the first time. I think it came from Autozone but I don't recall the brand. I've tried to only buy Ford tensioners since then.

The OP has replaced his tensioner multiple times with decent quality replacements and the noise always comes back. The likely hood of getting multiple defective tensioners is low IMO. I've installed several AutoZone brand tensioners w/out any problems, not that I'm saying they're particularly good quality. Dayco and Gates tensioners are fairly comparable to Motorcraft quality IMO.

 

[CDW6212R]

The OP has replaced his tensioner multiple times with decent quality replacements and the noise always comes back. The likely hood of getting multiple defective tensioners is low IMO. I've installed several AutoZone brand tensioners w/out any problems, not that I'm saying they're particularly good quality. Dayco and Gates tensioners are fairly comparable to Motorcraft quality IMO.

I agree completely, I only added to the list of people who have had new tensioners not work right. I agree he might just need a different belt length.

I used a bigger top idler pulley when a new alternator had a larger pulley and made the belt too short. There are lots of different belt lengths in the stock range, if the belt size isn't found easily, a different pulley can do the same thing.

 

[koda2000]

I agree completely, I only added to the list of people who have had new tensioners not work right. I agree he might just need a different belt length.

I used a bigger top idler pulley when a new alternator had a larger pulley and made the belt too short. There are lots of different belt lengths in the stock range, if the belt size isn't found easily, a different pulley can do the same thing.

Agreed, but if the alt pulley was larger, wouldn't you need a smaller idler pulley to use the same belt?

 

[CDW6212R]

Sorry, smaller alt pulley. That was about 2009 when I got that aftermarket alternator. I wanted to use the pulley it came with, for the idle current it was made for. Now I'd prefer to stick with a stock alternator pulley size, the 4G units are virtually all the same besides the couple of high end 250amp models. Mine was about $160 then, 170amp. It(DBA) wasn't that high of quality, went out after two years.

 

[239]

I went with a Bosch alternator but swapped the stock pulley over. I got a new steering pump in the last year so maybe the size changed. I do notice that my belt slips on easier than it did before all of that.

 

[239]

Update: I installed a new tensioner and it has a clear indicator. As you can see, it starts off with plenty of clearance, but closes and starts to hit the stop point when I put the truck in drive. That’s where the rattle is coming from. I’m going to try an 87” belt since I’m out of ideas.

 

[CDW6212R]

Those are great pictures. If the tensioner hits the stop point, that will be a noise, and the belt loosening up momentarily. I'd say a belt about 1/2" different than that existing belt will help.