You can find them at some part stores. They have been very handy for me when trying to find squeals.
Running engine without serpentine belt
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Elder User
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From: Medford, OR
Running engine without serpentine belt
In an effort to find an ever elusive and very annoying squeak I have when the motor is running, moving or not, I was curious if I could remove the serpentine belt and run it for a few seconds just to rule out any of the pulleys that aren't turning when they belt is off. Will this damage anything or is it just plain stupid? The squeak is noticeable immediately so I would know within 1 or 2 seconds if it has stopped. Thanks for any input.
Postmaster
Joined: Jun 2001
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From: Loveland, CO.
I ran mine without the belt for at least 30 seconds once, when I installed a new alternator and forgot to put the belt back on before starting it up (d'oh!). It did not cause any problems, and my 351 sounded tough as heck without the sound and drag of the driven accessories!
So, yes you can run it for a short amount of time with the belt off. Especially if the engine is cool. The only thing that is potentially hazardous when running without the belt is overheating the engine because the water pump is not spinning, but it would take longer than a few seconds or a minute to do any harm. And the battery will not be harmed by running without the alternator spinning for such a short period of time either.
So, yes you can run it for a short amount of time with the belt off. Especially if the engine is cool. The only thing that is potentially hazardous when running without the belt is overheating the engine because the water pump is not spinning, but it would take longer than a few seconds or a minute to do any harm. And the battery will not be harmed by running without the alternator spinning for such a short period of time either.
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Joined: Sep 2003
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good tip
wakeboarder,
i had a bad squeal too, it turned out to be the air pump (smog pump) on my 92 bronco, but the way i found it (and any other strange sounds) is a simple home made "mechanics stethoscope"
there are two versions, the fancy and plain version:
1.fancy - (i have this one) ok, take about a 3 to 4 foot section of heater hose and set aside. take an old pair of earmuff style hearing protectors and cut out a hole on the outside of one of the earmuffs (make it just a little smaller that the heater hose). now force about half an inch of the hose in the hole you cut out. you now can place the tip of the hose around and on suspect components and hear them making isolated noises. great for finding vacuum leaks, exhaust leaks, bad smog pump/alternator bearings, etc.
2. plain - take about a 3 to 4 foot section of heater hose and place on end to your ear and the other to the suspect component as listed above. not as cool, but will work.
MAIN THING TO REMEMBER - watch out for the cooling fan blades, i would hate to get the hose yanked off my head from letting it wrap about a spinning fan!
i had a bad squeal too, it turned out to be the air pump (smog pump) on my 92 bronco, but the way i found it (and any other strange sounds) is a simple home made "mechanics stethoscope"
there are two versions, the fancy and plain version:
1.fancy - (i have this one) ok, take about a 3 to 4 foot section of heater hose and set aside. take an old pair of earmuff style hearing protectors and cut out a hole on the outside of one of the earmuffs (make it just a little smaller that the heater hose). now force about half an inch of the hose in the hole you cut out. you now can place the tip of the hose around and on suspect components and hear them making isolated noises. great for finding vacuum leaks, exhaust leaks, bad smog pump/alternator bearings, etc.
2. plain - take about a 3 to 4 foot section of heater hose and place on end to your ear and the other to the suspect component as listed above. not as cool, but will work.
MAIN THING TO REMEMBER - watch out for the cooling fan blades, i would hate to get the hose yanked off my head from letting it wrap about a spinning fan!
Elder User
Joined: Aug 2004
Posts: 646
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From: Derbyshire, UK.
Even simpler is to use a long screwdriver - wrap your hand around the handle and place it agaisnt your ear and touch the tip to the engine. Any sound generated in that area will be transmitted up the shaft of the driver as a vibration. Its surprising how simple it is and works.
Simon
Simon
Postmaster
Joined: Jun 2001
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From: Loveland, CO.
I would pull the belt first and run it for a few seconds to see if it is one of the belt driven accessories or not. Because even with a stethoscope, long screwdriver, vacuum hose, etc. it is very hard to differentiate between which part is making noise. It probably is a belt or belt driven accessory, but it can't hurt to rule everything else out first. You can have that belt off and back on in two minutes, so it is not a hassle.
I had the same problem and tried to find it with the long screwdriver method. Then I went to a trusted shop and we put a stethoscope on it. You should have seen me, the mechanic, and the owner of the shop debating which part it was! Because the belt makes the sound go all around and travel, and you really cannot tell which part the noise is coming from. I replaced the tensioner pulley first, since it was cheap; no luck. So then I thought that it was the smog pump and ordered one. In the meantime I kept listening and then I purchased an alternator and put it on, that was the problem. That alternator was not very old, so I didn't consider it at first. Of course I cancelled the smog pump order.
The point is that the sound travels all over, via the belt, and since it is only the one belt, you can't eliminate parts one at a time. Anything that can be done to narrow the problem down is helpful.
I had the same problem and tried to find it with the long screwdriver method. Then I went to a trusted shop and we put a stethoscope on it. You should have seen me, the mechanic, and the owner of the shop debating which part it was! Because the belt makes the sound go all around and travel, and you really cannot tell which part the noise is coming from. I replaced the tensioner pulley first, since it was cheap; no luck. So then I thought that it was the smog pump and ordered one. In the meantime I kept listening and then I purchased an alternator and put it on, that was the problem. That alternator was not very old, so I didn't consider it at first. Of course I cancelled the smog pump order.
The point is that the sound travels all over, via the belt, and since it is only the one belt, you can't eliminate parts one at a time. Anything that can be done to narrow the problem down is helpful.
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From: Medford, OR
Those all sound like good ways to check so I will give that a shot. This stupid squeaking is driving me nuts. If I rev the motor it squeaks a bunch of times while the RPMs are coming back down and then will squeak off and on while idling or driving. I replaced the belt and tensioner thinking it could be those with no change. Thanks for the tips.
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From: Lutz, Fl
you know...i have that same exact problem right now... i tried belt conditioner, i tried another method on the belt and nothing fixes it. I think that the noise might be coming from the pulley on the bottom (im not sure what its called) because it when the engine is running. is it supposed to shake like that?
Postmaster
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From: Loveland, CO.
Originally Posted by bronson85
you know...i have that same exact problem right now... i tried belt conditioner, i tried another method on the belt and nothing fixes it. I think that the noise might be coming from the pulley on the bottom (im not sure what its called) because it when the engine is running. is it supposed to shake like that?
Postmaster
Joined: Jun 2001
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From: Loveland, CO.
As far as the belts in our trucks, these serpentine belts seem to have a habit of starting to squeak after a few months, and nothing really seems to make it go away for long. People here have talked about all sorts of things that they do to make the squeak stop, but it always comes back. When mine starts squeaking, I just replace it. While the belt is still good and I could get a lot more service out of it, I don't feel like fighting the squeak. A new belt is cheap enough to do once or twice a year, and it's certainly easy to change these belts, you don't really even need tools to do it. And I never have to worry about a broken belt, because they are always new! Not to mention that I kept one of the ones that I took off for squeaking, but could probably go another 25,000 miles, and I folded it up into the cardboard holder of the brand new one and I carry it in the truck, just in case.
5th Wheeling
Joined: Nov 2021
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From: Virginia
When I was trying to figure out which pulley was squeaking in one of vehicles someone told me to spray just a little water on the belt. If it stops, supposedly it's the belt, too loose or old. If it doesnt, it's a pulley. I then sprayed just a little water behind the pulley I suspected and the squeaking stopped. Changed it out and no longer squeaking. Just a thought.
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