Bad Belt Squeal Problem
03-19-2012, 10:52 PM
#1
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Bad Belt Squeal Problem
A little background first....
Been chasing a squealing belt for a long time. The car doesn't get driven much, and I always assumed that the battery was always close to dead (often completely dead) and putting a heavy load on the alternator, thereby causing a slightly loose or worn belt to squeal. AC compressor switch made it squeal almost 100% of the time, until I tightened it.
Recently, the AC compressor grenaded itself internally, creating massive amounts of squeal. Replaced the compressor, flushed the AC system, recharged the system, and everything was okay for a about a week, with the AC working great and belts quiet. Belt squeal came back today. Re-tightened belt, applied Belt Ease to get it to stick to the pulleys better. Today, when driving the car, the belt started squealing when the AC compressor was engaged, so I turned off the AC. Belt continued to squeal, then broke completely, accompanied by alot of smoke.
Got the car home, installed a new belt. Noticed the pulleys were slightly discolored from the slipping belt, and covered with belt dust. Didn't think it would be a problem. Tightened the new belt using 90 degree twist rule. Started car. Still squealing, but only when compressor is engaged. Battery reads 13V with car off. Alternator was tested during compressor change and passed the test on the charging machine. Battery is Optima Red, but has been completely flattened NUMEROUS times. All bolts are tight, pulley alignment looks okay, etc.
The question is - Is this an alternator problem, a compressor problem, or bad pullies? Has anyone had this level of belt squeal that was impossible to remedy. I would call myself extremely capable, especially with these cars, but this has me baffled. 944Ohm and I are thinking excessive AC compressor pressure could be causing too much strain on compressor. Could my condenser be partially blocked with FOD from grenaded compressor, creating too much pressure? Will bad electrical grounds and /or dying battery load the alternator to the point of stalling it? CAn slipping belt evetually wear down the pullies enough to make them ineffective at holding the belt? HELP PLEASE!
Chris
Been chasing a squealing belt for a long time. The car doesn't get driven much, and I always assumed that the battery was always close to dead (often completely dead) and putting a heavy load on the alternator, thereby causing a slightly loose or worn belt to squeal. AC compressor switch made it squeal almost 100% of the time, until I tightened it.
Recently, the AC compressor grenaded itself internally, creating massive amounts of squeal. Replaced the compressor, flushed the AC system, recharged the system, and everything was okay for a about a week, with the AC working great and belts quiet. Belt squeal came back today. Re-tightened belt, applied Belt Ease to get it to stick to the pulleys better. Today, when driving the car, the belt started squealing when the AC compressor was engaged, so I turned off the AC. Belt continued to squeal, then broke completely, accompanied by alot of smoke.
Got the car home, installed a new belt. Noticed the pulleys were slightly discolored from the slipping belt, and covered with belt dust. Didn't think it would be a problem. Tightened the new belt using 90 degree twist rule. Started car. Still squealing, but only when compressor is engaged. Battery reads 13V with car off. Alternator was tested during compressor change and passed the test on the charging machine. Battery is Optima Red, but has been completely flattened NUMEROUS times. All bolts are tight, pulley alignment looks okay, etc.
The question is - Is this an alternator problem, a compressor problem, or bad pullies? Has anyone had this level of belt squeal that was impossible to remedy. I would call myself extremely capable, especially with these cars, but this has me baffled. 944Ohm and I are thinking excessive AC compressor pressure could be causing too much strain on compressor. Could my condenser be partially blocked with FOD from grenaded compressor, creating too much pressure? Will bad electrical grounds and /or dying battery load the alternator to the point of stalling it? CAn slipping belt evetually wear down the pullies enough to make them ineffective at holding the belt? HELP PLEASE!
Chris
03-19-2012, 11:04 PM
#2
Drifting
Have you pulled the belt and checked the alternator pulley by hand for free and smootheness? See if the shaft moves as well as rotates. It could be your alternator bearings are going and when they heat up it freezes and kaboom. If that's not it, an A/C shop should help you get to the bottom of your issue.
03-19-2012, 11:27 PM
#3
Instructor
clean your grounds. Use clarks g write up you will kill the battery and yiu are not doin your alternator any favors. Get a battery tender to keep a full charge when your not driving regularly.
when the belt broke was it because something froze up? Did you look closely at the belt
when the belt broke was it because something froze up? Did you look closely at the belt
03-19-2012, 11:48 PM
#4
Today I got
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When my AC compressor grenaded itself internally on the highway outside of Gallop NM it completely shredded the belt and scared the **** outta me 
03-19-2012, 11:54 PM
#5
I'd for sure check out the pulleys. And the 90 method? Nah, those belts are super tight to spec. Forgive me for not knowing it offhand. I do know the power steering has a 5mm deflection.
Previous owners didn't know this and my belts squealed...squealed...squealed like a piggy.
Now? Dead silent.
Also, check your tensioner rods. Make sure those bolts are torqued DOWN.
Previous owners didn't know this and my belts squealed...squealed...squealed like a piggy.
Now? Dead silent.
Also, check your tensioner rods. Make sure those bolts are torqued DOWN.
03-20-2012, 08:40 AM
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Thanks all for the input. Here are some more details -
mytrplseven - When the belt was off, the alternator was spun by hand and it is smooth as silk. The alternator was actually taken to an auto parts store one week ago and they spun it up on their machine (i.e. whatever RPM it is supposed to turn) and checked it out. No noise from the bearings, output was fine, etc. The only thing they didn't do was put a super tight belt on it while testing it, as their machine uses a loose belt only. The alternator, to my knowledge, is original to the car.
1933beer - the ground are original to the car, and likely need to be addressed. However, the battery is always kept on a battery tender (in the last year), as the car will kill the battery when sitting for more than a few days. When I first leave the house, the belt was silent, but after the first restart or two, the squeal would come back when first started and go away after a few seconds or a high rev or two. Here's the question.... even if the electrical system was shot, the battery was stone dead, and the alternator was being worked to death, the belt still shouldn't squeal right? Also, the battery showed 13V last night with the car off, so I assume it is charged and good.
Butters944 - My passenger thought his seat was actually on fire when the belt broke due to the amount of smoke billowing into the cabin. It was hilarious.
River - all bolts were checked last night when I installed the new belt. Everything is super tight. As for the belt tension, the belt is what would call "wicked tight" given the front crank bearing works on hydrodynamic lubrication and has to overcome the force of the belt pulling towards the alternator side of the engine. It's amazing that bearing doesn't give up the ghost more often.
Tonight I plan to go back in, remove the belt, check all pulleys for wear and clean them, making sure to scrape out anything that might be in the grooves. I will blast them all with carb cleaner, then lightly sand them with 300 grit perpendicular to the grooves for the best possible grip on the belt. I'll soap and water the belt, let it dry, and re-install. I have zero faith that this will have any affect. Any other suggestions?
mytrplseven - When the belt was off, the alternator was spun by hand and it is smooth as silk. The alternator was actually taken to an auto parts store one week ago and they spun it up on their machine (i.e. whatever RPM it is supposed to turn) and checked it out. No noise from the bearings, output was fine, etc. The only thing they didn't do was put a super tight belt on it while testing it, as their machine uses a loose belt only. The alternator, to my knowledge, is original to the car.
1933beer - the ground are original to the car, and likely need to be addressed. However, the battery is always kept on a battery tender (in the last year), as the car will kill the battery when sitting for more than a few days. When I first leave the house, the belt was silent, but after the first restart or two, the squeal would come back when first started and go away after a few seconds or a high rev or two. Here's the question.... even if the electrical system was shot, the battery was stone dead, and the alternator was being worked to death, the belt still shouldn't squeal right? Also, the battery showed 13V last night with the car off, so I assume it is charged and good.
Butters944 - My passenger thought his seat was actually on fire when the belt broke due to the amount of smoke billowing into the cabin. It was hilarious.
River - all bolts were checked last night when I installed the new belt. Everything is super tight. As for the belt tension, the belt is what would call "wicked tight" given the front crank bearing works on hydrodynamic lubrication and has to overcome the force of the belt pulling towards the alternator side of the engine. It's amazing that bearing doesn't give up the ghost more often.
Tonight I plan to go back in, remove the belt, check all pulleys for wear and clean them, making sure to scrape out anything that might be in the grooves. I will blast them all with carb cleaner, then lightly sand them with 300 grit perpendicular to the grooves for the best possible grip on the belt. I'll soap and water the belt, let it dry, and re-install. I have zero faith that this will have any affect. Any other suggestions?
Last edited by cwigg66; 03-20-2012 at 10:46 AM.
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03-20-2012, 05:13 PM
#8
Resistance is Futile
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Now if you *really* want to have fun:
1. Go get a belt that is shorter and bypass the compressor altogether.
2. put 12v on the compressor and without car running hammer the compressor with an air gun to test head pressure build.
Two separate tests...
I'd do the the short belt test to see if your alternator bearings are pissed off.
1. Go get a belt that is shorter and bypass the compressor altogether.
2. put 12v on the compressor and without car running hammer the compressor with an air gun to test head pressure build.
Two separate tests...
I'd do the the short belt test to see if your alternator bearings are pissed off.
03-20-2012, 09:08 PM
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Sorry about that 75Ohm... was in a bad place....
Okay.. at last I have determined the problem. The culprit is certainly the compressor. Checking pressures tonight, I discovered that something in the AC system is blocked. At idle, the low side pressure site around 30 PSI. Revving the engine, low side dips down to 10 PSI or so, then immediately spikes to 70+ PSI and the belt starts screaming like crazy.
So, who knows how to troubleshoot a clogged AC system? IS it truly clogged? Anything else that could cause this? This is a brand new compressor, and worked well for a week or so. I bled some of the pressure off the low side when the pressure spiked, and out came a ton of very blackish gray oil. Bear in mind that I flushed the condenser side of the system before I installed the new compressor. The new compressor was pre-oiled according to the label. Could i be over-oiled. Not enough? The old compressor died a horrible death, and there was some small metal shavings at the manifold when I pulled it, hence the flush. Dryer was replaced as well.
IS it time to bite the bullet and take it to an AC shop? Anyone on the southside of Atlanta wanna come help troubleshoot it?
Thanks for all the help guys. Gotta love Rennlist.
Chris W.
Okay.. at last I have determined the problem. The culprit is certainly the compressor. Checking pressures tonight, I discovered that something in the AC system is blocked. At idle, the low side pressure site around 30 PSI. Revving the engine, low side dips down to 10 PSI or so, then immediately spikes to 70+ PSI and the belt starts screaming like crazy.
So, who knows how to troubleshoot a clogged AC system? IS it truly clogged? Anything else that could cause this? This is a brand new compressor, and worked well for a week or so. I bled some of the pressure off the low side when the pressure spiked, and out came a ton of very blackish gray oil. Bear in mind that I flushed the condenser side of the system before I installed the new compressor. The new compressor was pre-oiled according to the label. Could i be over-oiled. Not enough? The old compressor died a horrible death, and there was some small metal shavings at the manifold when I pulled it, hence the flush. Dryer was replaced as well.
IS it time to bite the bullet and take it to an AC shop? Anyone on the southside of Atlanta wanna come help troubleshoot it?
Thanks for all the help guys. Gotta love Rennlist.
Chris W.
03-20-2012, 10:58 PM
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When first switched on, low side is 30 PSI, high side is 100 PSI. After one rev above 2000 RPM, low side spikes and stays t about 80 PSI, high side remains 100 PSI.
03-20-2012, 11:08 PM
#13
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You have a clog. You're building up pressure that can't get through the system... low side a bit too high, high side a lot low.
Dumb question -- sure you have the lines hooked up at the compressor correctly?
Dumb question -- sure you have the lines hooked up at the compressor correctly?
03-21-2012, 08:44 AM
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Yes I'm sure. The AC was working for a week remember! This is a recent event. So do you think that an AC shop will be able to get it working? This car has never been to a mechanic in the 9 years I've owned it, nor have any of my vehicles. However, I know when I am over my head, and diving into an in-depth AC system diagnostic isn't on my list of stuff I want to do. I have another car to build. I'll get a quote from a local shop and see what they say.
Chris
Chris