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Old 10-26-2012, 12:32 AM   #1
Dan99
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Screeching Noise when Accelerating, so what pulley is involved?

Silly me, I swapped out my pullies (idler & tensioner) and my belts (both ac and serpintine) because my car would screeched after starting the car. I was so certain that this was my problem that I did not bother to test out the other pullies. Fortunately, the reduction of screeching noise has been eliminated during idle, but not when I accelerate. It does however goes away after minimal driving. My question is, which pulley(s) most likely needs to be replaced?

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Old 10-26-2012, 06:53 AM   #2
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If you didn't replace the AC tensioner pulley, I'd begin there, but I'd also look to ensure that your belt is aligned squarely...as in, maybe you did what I did...before I caught it...idler pulley pin needs to be in notch.

Conceivably any pulley could screech...maybe get someone to rev up the car and listen using a hose as stethoscope?
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Old 10-26-2012, 07:58 AM   #3
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If you didn't replace the AC tensioner pulley, I'd begin there, but I'd also look to ensure that your belt is aligned squarely...as in, maybe you did what I did...before I caught it...idler pulley pin needs to be in notch.

Conceivably any pulley could screech...maybe get someone to rev up the car and listen using a hose as stethoscope?
thanks dmax, but i'm not sure what you mean by the "idler pulley must be in notch" ?

I'll look it up though.


if you're talking about the pin on the idler pulley, it was already pre-attached prior to installation.
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Old 10-26-2012, 09:42 AM   #4
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Test them by spinning them if they move freely like a skateboard wheel they need replacing
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Old 10-26-2012, 10:23 AM   #5
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thanks dmax, but i'm not sure what you mean by the "idler pulley must be in notch" ?

I'll look it up though.


if you're talking about the pin on the idler pulley, it was already pre-attached prior to installation.
On Pulley 1 (in your pic) there is a small notch on the back that fits into a groove on your alternator. I think that's what Dmax is referring to.
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Old 10-26-2012, 11:07 AM   #6
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Screech on acceleration? Do you have a manual transmission? Does the engine speed increase faster than the car speeds up?

One thing to consider is the clutch/torque converter. If the screech can be reproduced while the car is stationary -- parked in your driveway -- then you can discount the clutch and torque converter (manual and automatic, respectively) as the source. But if the car must be moving to reproduce the screech, then you must consider these parts as the cause of your problem.

I asked if you had a manual transmission because a worn clutch is far more likely to produce noise and slippage, but as I write this it occurs to me that a torque converter can play into this symptom too. AND, you have an xi, so there are transfer case components to think about as well. But, any transmission/drivetrain related issue that makes a screech would almost always demand the car be moving to make the suspect noise. If the car is parked and making noise, then it makes sense to dial in on the belts and pullies first. One should be able to simply raise the hood and determine that the noise is coming from the front of the engine or the back, and diagnose further from there.
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Old 10-26-2012, 11:33 AM   #7
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anyone have any torque specifications on these pulleys? i always wondered if there such a thing as too much/too little torque for these items.
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Old 10-26-2012, 12:26 PM   #8
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Quote:
Originally Posted by jdstrickland View Post
Screech on acceleration? Do you have a manual transmission? Does the engine speed increase faster than the car speeds up?

One thing to consider is the clutch/torque converter. If the screech can be reproduced while the car is stationary -- parked in your driveway -- then you can discount the clutch and torque converter (manual and automatic, respectively) as the source. But if the car must be moving to reproduce the screech, then you must consider these parts as the cause of your problem.

I asked if you had a manual transmission because a worn clutch is far more likely to produce noise and slippage, but as I write this it occurs to me that a torque converter can play into this symptom too. AND, you have an xi, so there are transfer case components to think about as well. But, any transmission/drivetrain related issue that makes a screech would almost always demand the car be moving to make the suspect noise. If the car is parked and making noise, then it makes sense to dial in on the belts and pullies first. One should be able to simply raise the hood and determine that the noise is coming from the front of the engine or the back, and diagnose further from there.
yeah, I have a manual. it makes the screeching noise when i apply the gas pressure in neutral, so according to your reasoning, this should rule out any converters.
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Old 10-26-2012, 12:28 PM   #9
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Originally Posted by 325kev View Post
On Pulley 1 (in your pic) there is a small notch on the back that fits into a groove on your alternator. I think that's what Dmax is referring to.
yes this pin is in...
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Old 10-27-2012, 06:19 AM   #10
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As I said, if you didn't replace your AC tensioner pulley, it could be that...but it could be any other pulley/bearing...WP, PS, AC, Alt...try to isolate sound with a hose...like a 5' section of garden hose or my favorite stethoscope...a 5' section of 1" diameter flexible electrical conduit, available from HD, along with the xl50!
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