Need help identifying a squealing noise

[Joseph E.]

I'm helping my cousing with one of his cars and have run into a problem that neither one of us can identify or resolve. The car is a 1970 coupe with a 454 engine in it. The problem we're having is a squealing noise that begins when the two electric fans on the aftermarket radiator are started. It's got a mechanical water pump (new Edelbrock unit), power steering (new pump as well) and a Powermaster alternator (also new). When the engine is fired, it sounds fine with no unusual noises. Once the electric fans on the radiator are turned on, there is an almost immediate squeal (similar to a bad bearing) that emanates from the front of the engine. If the fans are turned off, the squeal goes away. The fans are brand new Spal units as well and were installed with the radiator only a few weeks ago. I don't understand why all is quiet UNTIL the cooling fans are turned on. Does any member have a suggestion as to the cause of the noise we're hearing? Any input would be appreciated. Thank you.

Joe 45420

[Norm B.]

Re: Need help identifying a squealing noise

Is the alternator belt loose? Two electrically driven fans could draw enough power to cause that belt to slip if it is not tight enough. I always say check the cheap and easy stuff first.

[Michael D.]

Re: Need help identifying a squealing noise

You have pretty much isolated the squeal to the aftermarket fans.

[Edward J.]

Re: Need help identifying a squealing noise

Joe, I am with Norms post, a easy way to check to see if its a loose belt is to take a socket that fits the alternator pulley nut and see if the pulley rotates freely around the belt, if so adjust the belt tension, or maybe the belt is glazed badly and requires replacement.

[Stephen L.]

Re: Need help identifying a squealing noise

An easy way to isolate a noise is, using a broom stick or similar rod, place one end of the stick on the item in question with the other end touching your ear. The noise level will "transmit" thru the broomstick to your ear. Be careful not to get the broomstick tangled in the moving parts.

[Wayne W.]

Re: Need help identifying a squealing noise

A BB with AC and PS has a strange belt arrangement that puts a lot of stress on the idler pulley, and the PS pulley. The belts often squeal when electrical things are turned on or the battery is charging. Put a very good and tight belt on the idler, and replace the alternator and PS drive belts. Make sure those alternator brackets are not cracked or broken which is common.

[Joseph E.]

Re: Need help identifying a squealing noise

An easy way to isolate a noise is, using a broom stick or similar rod, place one end of the stick on the item in question with the other end touching your ear. The noise level will "transmit" thru the broomstick to your ear. Be careful not to get the broomstick tangled in the moving parts.

Thanks to the members who responded with suggestions about isolating the noise problem. We've already tightened and loosened the belts thinking that either a too tight or too loose belt was the noise source. Neither way changed anything. My cousin told me that the belts are new but I'll see if he can pin down when they were last replaced. The electric fans are not squealing themselves because if we run just the fans without the engine running they make absolutely no noise no matter how long they run. I will check the alternator bracket since that is something that hasn't been looked at for cracks. We'll also try the "listening" technique the next time we're working on the car and the noise is heard. Perhaps that will isolate the problem. I sincerely appreciate the input. Thanks again.

Joe

[Tom L.]

Re: Need help identifying a squealing noise

Have you tried to remove the belt completely and see if the squeel is there without the belt?? If no belt = no squeel you've found the problem. Had a similar issue on a racecar years ago. Just a thought. Good luck!!

[Dick W.]

Re: Need help identifying a squealing noise

Does it have the second belt on the waterpump? Is the idler pulley there?

[Edward J.]

Re: Need help identifying a squealing noise

Thanks to the members who responded with suggestions about isolating the noise problem. We've already tightened and loosened the belts thinking that either a too tight or too loose belt was the noise source. Neither way changed anything. My cousin told me that the belts are new but I'll see if he can pin down when they were last replaced. The electric fans are not squealing themselves because if we run just the fans without the engine running they make absolutely no noise no matter how long they run. I will check the alternator bracket since that is something that hasn't been looked at for cracks. We'll also try the "listening" technique the next time we're working on the car and the noise is heard. Perhaps that will isolate the problem. I sincerely appreciate the input. Thanks again.

Joe

Joe sometimes belt tension is not always the problem, a belt with a glazed surface(shiney) will slip and squeel. And generally with electrical loads such as the electric fans this will cause a belt to slip around the pulley(s).

[Tom L.]

Re: Need help identifying a squealing noise

Didn't notice that it's a big block car. My '72 LS-5 squeeled over 1500rpm without the second (inner) belt on it. Mine is an A/C car so I suppose the 7 blade fan was the reason on my car.

[Paul J.]

Re: Need help identifying a squealing noise

Joe, put a little soft soap under the belt on the friction side in a couple of places. Just a little thin coat, it doesn't take much. If the noise disappears, then it's the belt. If it's still there, then it's an accessory.

Paul

[Joseph E.]

Re: Need help identifying a squealing noise

To All Members Who Offered Advice,

We tried all of the things suggested that we hadn't already done but to no avail. The noise was still persistant. We decided to remove the pulley from the water pump and found that there was a hairline crack between two of the bolt holes in the pulley that could only be seen if it was removed from the engine. The damaged pulley has been replaced and the noise has not returned. Thanks for all the help and suggestions in resolving this problem.

Joe 45420