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Hi I have a 98 Pontiac firebird and for the past few days im hearing this squeaking mouse like noise under the hood when I first start the car. When I drive for a few miles you could still hear it while driving but then it goes away. I took it to a mechanic shop and their telling me to replace the belt tensioner assembly. They are telling me that the belt assembly is loose and that is why it is making that noise.They are telling me an estimate of $250? I would like to get an opinion from this forum that if there is a cheap fix for replacing the whole assembly. Can somebody please let me know. Thank you
Last edited by Mike1711; Sep 11, 2018 at 12:46 PM.
You mean this guy, or is it a more complex belt tensioner? I replaced one on a Chevy Suburban once and the OEM part was less than $50 and it took less than 20 minutes, including dealing with the belt. That's why I asked if you had some kinda fancy tensioner for them to quote $250.
If you have a socket set with a long breaker bar, this is one of the easiest things to do on the car. (It's a $60 part that takes 15 minutes to change. So, you can determine if you think $250 is a fair price for that.) However...
Originally Posted by Mike1711
I took it to a mechanic shop and their telling me to replace the belt tensioner assembly. They are telling me that the belt assembly is loose and that is why it is making that noise.
I would trust but verify on this one... Actually, I would probably just verify and not necessarily trust at all. This doesn't sound right and life (on a car like we have isn't so simple.)
At the age of these cars, all the pulleys on the tensioners are also going to squeak. When one is replaced, the next one can be heard. Squeaks like this often take a while to nail all the way down and eliminate fully.
The tensioner has marks on it, which you can visually check:
There are two raised notches on the side of the spring mechanism that attaches to your engine (other end from the pulley) and one raised notch on the arm that holds the pulley. The single notch is supposed to be in the middle of the two notches for normal operation. If your single notch is between the double notches on your car and that situation doesn't change when the engine is revved - then your mechanic is peddling you a bunch of BS.
If the tensioner is loose (you can move it by hand, without a bar) or if the notches move around when the engine revs, then the tensioner is bad.
If the tensioner isn't bad and the single notch is outside of the doubles, then that typically means that the belt is stretched or the wrong size.
BTW - If your tensioner was bad, I would expect the noise to happen whenever the engine revs or goes under load.
Noises that happen when the car starts (cold) and go away over time (warm) are typically due to temperature or expansion/contraction. You may have a bad tensioner pulley, but that's no reason to change the tensioner. (The pulley, like all the other pulleys, can be changed individually.)
I agree with @wssix99 that it's likely a pulley rather than the tensioner itself, though many folks just replace the whole assembly when doing it themselves (this is what I have done). But, as he mentioned above, there can be other sources of this noise as well - such as the idler pulleys. There are two tensioner pulleys and two idler pulleys (one of each for the main system, and one of each for the A/C system). Often, all four of these pulleys will need to be replaced around the same mileage to eliminate all squeaking. If you buy them and do the work yourself, it's not terribly expensive. Paying shop prices (and labor) for all of these would be a different story. It could also be the belt itself (either or both) that's getting old and making noise. On my '02 car, I had to replace everything listed above (main and A/C tensioner assemblies, plus main and A/C idler pulleys, plus main and A/C belts) to finally get rid of all the squeaking/chirping (which started right around the ~100k mile mark).
I replace the tensioners and all the pulleys at the same time....jus sayin
I do, too. And that's the thing and a great point. Even if one finds a single noisy pulley (with the age of these cars), a few weeks later the next one could start making its own noise.
The tensioner itself wears out (spring tension) which causes it to not keep enough pressure on the belt which causes it to slip (squeak). Also the pully on the tensioner bearing can fatigue so best just to buy the assembled tensioner vs just replacing the pulley part.
Get a tensioner with a metal vs plastic pulley
The separate "idler" pulley may also need replacing.
Best to just pop the belt off and spin the various pulleys and accessories to confirm all turn freely and do not bind or make noise. Replace any as needed.
These are all fairly simple "front of motor" things to replace with simple hand tools
Shop charging $250 to replace a $50 part that will take 10-15 minutes is a very high price to pay for a very simple job
You mean this guy, or is it a more complex belt tensioner? I replaced one on a Chevy Suburban once and the OEM part was less than $50 and it took less than 20 minutes, including dealing with the belt. That's why I asked if you had some kinda fancy tensioner for them to quote $250.
hi it’s for a 98 Pontiac firebird. No it’s just a regular belt tensioner and I got this price quote from the big mechanic shops.
Its two bolts, and its on topside of the engine (waterpump). Couldnt be easier. Likely cost about 40 bucks for a new one.
would you happen to have a picture of the belt tensioner assembly. When I search it so many pictures show for the belt assembly on a 98 Pontiac firebird. Thank you
If you have a socket set with a long breaker bar, this is one of the easiest things to do on the car. (It's a $60 part that takes 15 minutes to change. So, you can determine if you think $250 is a fair price for that.) However...
I would trust but verify on this one... Actually, I would probably just verify and not necessarily trust at all. This doesn't sound right and life (on a car like we have isn't so simple.)
At the age of these cars, all the pulleys on the tensioners are also going to squeak. When one is replaced, the next one can be heard. Squeaks like this often take a while to nail all the way down and eliminate fully.
The tensioner has marks on it, which you can visually check:
There are two raised notches on the side of the spring mechanism that attaches to your engine (other end from the pulley) and one raised notch on the arm that holds the pulley. The single notch is supposed to be in the middle of the two notches for normal operation. If your single notch is between the double notches on your car and that situation doesn't change when the engine is revved - then your mechanic is peddling you a bunch of BS.
If the tensioner is loose (you can move it by hand, without a bar) or if the notches move around when the engine revs, then the tensioner is bad.
If the tensioner isn't bad and the single notch is outside of the doubles, then that typically means that the belt is stretched or the wrong size.
hi hi so basically it can be a bad belt or bad tensioner? The belt is the correct size. The squeaks starts when you turn on the cold start but once the car gets warm the squeak goes away.
BTW - If your tensioner was bad, I would expect the noise to happen whenever the engine revs or goes under load.
Noises that happen when the car starts (cold) and go away over time (warm) are typically due to temperature or expansion/contraction. You may have a bad tensioner pulley, but that's no reason to change the tensioner. (The pulley, like all the other pulleys, can be changed individually.)
hi yes you’re exactly right. When I start my car the car squeaks when the car is cold but when it gets warm the noise goes away. If I leave the car how it is would it affect the car in anyway? Are you saying it best to replace the whole best assembly or the just the pulley with the belt? Thank you for your help
You sure it's the main belt tensioner or a/c belt tensioner?
My '01 Z28 has the original main tensioner with 110k on it and it's fine. The problem I had a while ago was with the a/c tensioner, the tensioner itself wears and causes the pulley to tilt and the belt runs across the pulley sideways making it squeak.
Doesn't matter if the a/c is on or not.
would you happen to have a picture of the belt tensioner assembly. When I search it so many pictures show for the belt assembly on a 98 Pontiac firebird. Thank you
go to rockauto.com and enter your vehicle 411 and look at the various brands they have. My $.02 is get one with a metal pulley vs plastic but there are several options
belts stretch and get harder when they age so they can slip and also the belt tensioner "spring" wears so it des not keep the intended tension on te belt. Common to replace belt tensioner when replacing a belt
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Belt Tensioner Assembly Replacement? 
