Hot Rods Still have a squeeling alt.

34Larry, I might try that.Thanks Bruce.

 

2many projects every thing is lined up.Thanks Bruce.

 

Sun Beam it seems to come and then disappear even just driving it down the road? Thanks Bruce.

 

If it isn't squealing almost every time after startup I'd look at other accessories.

 

We installed a new Cummins M11 engine in a material handler and had what sounded like a belt squeal at high rpm under load. We tried changing pulleys and the serpentine belt but it still squealed. I listened with a stethoscope with a tube attached while it was operating and traced the noise to the intake manifold. When I removed the manifold which had come assembled on the new engine, I found it didn't have the correct gasket so it didn't cover the port completely. Under load, the turbo pressure increased and pushed air past the gasket making the noise.

 

A piece of garden hose, or heater hose, about 3 feet long, is excellent for finding the source of mysterious noises.

Be careful around moving parts.

 

Sounds like the belt is too narrow for the pulley so the sides are not making contact as much as the bottom and that is slipping on the pulley. Just try a wider belt. You don't want the bottom of the belt touching the pulley, just the sides.

 

Thanks for all your help guys I have the Buck wagon back in the shop but at 17 degrees I aint going down there to work on it even if I do have 2 heaters LOL. Sat. and Sun it is going to warm back up near 60 degrees I will give it a shot again.Thanks Bruce,

 

Ok, I don't want to get us tossed here, but V-belt or serpentine? If it's serp get a new belt. It's a GM thing and wet rainy days make it worse. Mrs Highlander's OT SUV (cough-cough H-cough-3) does it but goes away when everything warms up. The previous car was just damn hateful, sounded like some 300K mile turd on cool damp mornings. A new belt would net about 2 years of quiet and then come back. If it's V-belt, sorry. Carry on...

 

I’ve been reading this post and like most others here, trying to figure out what’s going on with your squeal.
This post gives me a clue... if something comes and goes, there is usually something that triggers the problem.
You may want to pay close attention as to when the squeal comes and when it quits. Something is changing, try to figure out what it is.
Being a mechanic is kinda like being a police detective, you have to look for clues that lead you to the problem.


Bones

 

That's called diagnosis....My late model truck alternator sings like a really loud whistle/squeal when it's cold , been doing it for 15 years....

 

Good point. Something as simple as hitting the brakes if there's some abnormal current draw in the circuit.

There's always ear plugs..

 

"Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth." - Arthur Conan Doyle

 

Could be when the fan clutch kicks in.

 

I'd tend to agree with this, even tho' it's a new alternator. Worse things have come off the shelf.

On another note (no pun intended), I had an off-topic 67 Dodge with A/C that I could never stop the medium rpm "hum" when the A/C was on.
Replaced the so-called matched V-belts, and it still made that noise.
Made up a bracket with an idler pulley to support the belts at about mid-point.

Never could get rid of that vibration / hum.

 

HIGHLANDER , its a v belt.Thanks Bruce.

 

Bruce, GM stuff runs the AC compressor when you use the defroster to help dehumidify the interior. Just another thing you could check.

 

Like OJ said
Had this problem years ago with a Pontiac 231 V-6, the parts store had the wrong v belt listed it was same length but to narrow.

 

I am going to try a v belt this weekend. Bruce.

 

Instead of throwing parts at it, how about giving us a look? post several pictures from different angles. And maybe some video of it running, and you rev up the engine.

Perhaps we will have better specific questions that way....

 

Had the same problem with an OT 1990's Nissan pickup.

 

I think we have got away from basic diagnosis, maybe. The first thing Bruce needs to do, is make sure it’s a belt squealing and then figure out which belt is squealing.
Then determine under what conditions it starts squealing.
Everyone here has given most, if not all, reasons for squealing belts. I bet one of them is the reason.
Back in the old days, shops had a carbon pile resistor, that would make the alternator/generator put out max amps. It would fool the car into thinking the battery was severely discharged. Maybe Bruce could find one of those old shops and try that. Could point to a problem......or eliminate one.
That’s one way to diagnose, eliminate possibilities. Just thinking out loud. Lol



Bones

 

Squirrel, I tried a v belt and same thing.I will take some pictures of the motor{because I will be working on it all day Sun.}before I take it back apart.I know it wasnt squealing before I replaced the water pump so may be some thing isnt a line right. I had the alt . tested and it is working. When I lossen the alt. belt the squealing stops. So hang on till tomorrow and I will let you all know. Thanks for all the ideas. Bruce.

 

Be sure to include a good alt. pulley pic as well. To bad you don't still have the old unit to compare pulley's. Maybe belt is only making contacted with the floor of the pulley?

 

Sounds like your on the right track. I had this same type of problem on a older truck. Its a pain in the butt but I took all the belts off and then put one belt back on and checked it. If it was not the problem i then took it off and tried the next one (on and off) until it was diagnosed. Mine had 3 belts, once i figured out which one it was I then put the 2 belts that weren't a problem back on to make sure the squealing didn't start back. Its trouble but in eliminates all the scenarios. Mine was a water pump. Even today, just because something is new and test well doesn't mean its good under a load. Hope this helps

 

Wow! I think I better get one of those things. I don't know it I could press 138# with my whole hand, let alone just a finger!

 

Could it be the backing plate on the water pump being too close and the impeller is making audible contact?

 

I went through this when I bought my 30. I did about everything as you have. I still have it and I believe it is in the current in the alternator. It only happens at a very slight tip in of the gas (very slight) when I am driving. A little more gas it goes away, off the gas it goes away. I have listened to it for 4 years and really believe it is a current inside the alternator.

 

Heres a couple pictures.I took everything back off down to the water pump and sanded and cleaned all the pulleys.I know in the picture the alt belt looks crooked but it isn't.Yes its still squealing.Bruce.

 

1 more picture.