Belt tensioner rattle

[masospaghetti]

I tried installing 2 new Dayco tensioners (which are a different design than the original tensioner) and both of them chatter at low RPM, high load condition. It sounds like a heatshield rattle, but it goes away when I reinstall my old tensioner. I also tried a new Gates tensioner which looks almost identical to the original, and it also chatters.

I was replacing my old tensioner as preventative mtc, it still seems to work fine, and I believe it's the original part.

Why would the new tensioners chatter? Is it worth getting a Motorcraft unit? (The picture of the Motorcraft unit looks identical to the one used by Gates, so i'm guessing they are actually the same part)

2000 Explorer, 4.0 OHV, 5-speed manual, 144,000 miles. Thx all!

 

[yavapaires]

I assume you are refering to the serpentine belt tensioner, correct? I assume you are refering to the pully/bearing? Or are you refering to the spring part of the tensioner? did you spin the pulley prior to installing it? Did ANY of the pulleys rattle when spun by hand? Most pulleys are replaceable without replacing the complete tensioner. If the spring, I have no idea. It would be highly doubdtful to get three bad tensioners. I would test the bearing of the original one and reinstall it, if it is not making any noise.

 

[SoNic67]

Maybe the belt is too stretched and the new tensioners are pulling it harder and hit the limiters?
If you didn't have enough "pull" with the new tensioners, the belt would slip and slip and squeal, not "chatter".
Probably the old tensioner has a weaker spring and does not hit the limiter but still enough tension for the belt not to slip>

 

[masospaghetti]

Sorry, I wasn't totally clear on my post. I replaced the entire tensioner assembly (spring assembly and pulley) with three new units. All of them rattled. I agree it seems unlikely that three new units, with 2 different designs from two manufacturers, would all behave this way.

Again the old tensioner still works fine and the pulley still spins freely and smoothly, I just thought it would be a good preventative item to replace.

 

[masospaghetti]

Maybe the belt is too stretched and the new tensioners are pulling it harder and hit the limiters?
If you didn't have enough "pull" with the new tensioners, the belt would slip and slip and squeal, not "chatter".
Probably the old tensioner has a weaker spring and does not hit the limiter but still enough tension for the belt not to slip>

Makes sense, but the belt is about 6 months old, I can't believe it's stretched to that point yet.

 

[yavapaires]

Sorry, I wasn't totally clear on my post. I replaced the entire tensioner assembly (spring assembly and pulley) with three new units. All of them rattled. I agree it seems unlikely that three new units, with 2 different designs from two manufacturers, would all behave this way.

Again the old tensioner still works fine and the pulley still spins freely and smoothly, I just thought it would be a good preventative item to replace.

On every one I have had to replace, they have all started to make noise,vibration,squealing, or bearing noise before they died. It sounds to me like you keep a good eye or ear on things. They last a long time. I would wait for a problem to show itself before I got too worried about replacing the tensioner.

 

[frankenfreak]

idler pully

I cant find a pic to see if the OHV has an idler pulley for the serpentine belt. I had to replace mine on my OHC when I replaced my tensioner pulley. Mine was worn out and rattling. My new pullies were also a little different from stock.

 

[scdix50]

I am going through the same problem. I have had Gates, Dayco and now AC/DELCO tensioners. In the past I have been running 85.8 belts by Gates & Dayco. I just got a New Goodyear Gatorback belt in 85.8 and there no way to get on. I guess the others were a little longer than stated size. Today I ended up putting the Dayco tensioner w/pulley from new AC/DELCO and a old Gates belt that is 86.5 on to run until my new Goodyear Gatorback in 86.5 comes in. By the way, I have new alternator, new power steering pump, new AC clutch & bearing hub assembly. Ilder pulley has less than 9K miles. My new belt should be in by the first of the week. Will post update after I try out the new gatorback and the new 4 Seasons tensioner pulley.

 

[yavapaires]

I cant find a pic to see if the OHV has an idler pulley for the serpentine belt. I had to replace mine on my OHC when I replaced my tensioner pulley. Mine was worn out and rattling. My new pullies were also a little different from stock.

Yes, they do. Right front below the alternator. Do yourself a favor, go get a tool to relieve the tensioner pressure. There is very little room between the fan and tensioner for a ratchet. At least that is the case on my 96 4.0 OHV

 

[masospaghetti]

Thanks all for the information. Small update:

With the new Gates tensioner, it does appear to be at its wear limit based on the wear indicator, even though the belt is almost new. Will try a new belt from another manufacturer.

 

[masospaghetti]

Put a new Gates Micro-AT belt in from Napa ($49.99!!, wtf) and the belt is obviously shorter, the Dayco must have stretched. Pretty bad that it stretched beyond use within six months or so, considering it was their Poly Rib "premium" belt. So far, quiet with the new belt and tensioner.

 

[scdix50]

I am going through the same problem. I have had Gates, Dayco and now AC/DELCO tensioners. In the past I have been running 85.8 belts by Gates & Dayco. I just got a New Goodyear Gatorback belt in 85.8 and there no way to get on. I guess the others were a little longer than stated size. Today I ended up putting the Dayco tensioner w/pulley from new AC/DELCO and a old Gates belt that is 86.5 on to run until my new Goodyear Gatorback in 86.5 comes in. By the way, I have new alternator, new power steering pump, new AC clutch & bearing hub assembly. Ider pulley has less than 9K miles. My new belt should be in by the first of the week. Will post update after I try out the new gatorback and the new 4 Seasons tensioner pulley.

An update to the above message, After reinstalling the 86.5" belt and drove 25 miles back home the chirpping stoped. Yesterday I looked everything over to see what was going on. I found the belt had jumped one grove back on the harmonic balancer and thus realigned it's self with the tensioner pulley. Today I when into search and found many threads on harmonic balancer failure. I have ordered a new one from ROCKAUTO.COM...SOOO, If you have a chirp, check your pulleys, your belt and then your harmonic balancer before spending a lot of money on tensioners. In all the years I have been working on Fords I have never had to replace a harmonic balancer. Lesson learned.