High Pitched Screaming Sound From Engine Somewhere

[Ludigdrums]

Well, I was out driving during this beautiful day today, and somehow got stuck in some traffic, and started to notice this real annoying high pitched sound coming from somewhere. Of course I assumed it was someone elses poorly cared for automobile. Much to my dismay, I finally realized that it was my '81 Vette. All the temps were fine and it was running fine as well.

Just the other day I had replaced a heater hose from the manifold to the heater core, and refilled anti-freeze in the radiator and overflow tank.

I also noticed that I was a little low on power steering fluid.

I seem to remember once before when I was low on power steering fluid, that I got a weird high pitched sound as well. I haven't been able to refill and check yet.

Also, the sound varies with engine speed, and almost seems to go down in pitch as engine speed rises, and when I shut of the car, I hear it die down with the engine. It was really hard to place where the sound was coming from...it almost seemed like it was coming from the air cleaner assembly. I also noticed that the fuel filter seemed to be bubbling...which I don't remember it doing normally.

Thanks for reading through all this if you made it...I know it's long!

Any thoughts?!?!

Thank You!

- Jeremy

 

[78SilvAnniv]

Maybe you can check to see if you have a pinhole leak spraying water on the belts? A wet and slipping belt will change noises at varying speeds as it dries or the moisture is dissipated.

If the noise varies when you turn the wheel, I'd suspect the ps reservoir to be low, but you just checked that. Perhaps you had spilled some oil or coolant on the belts...how long would that take to dissipate? I'd have thought it would have quit already if it was a small spill.

Could one of your accessory parts be going bad and the belt is slipping over its' pulley? Fan clutch? Alternator? Power steering? AC?

Sorry, I am just tossing things out there as they come into my head...sort of like when I'm looking for my favorite shirt in the laundry.
Heidi

 

[wishuwerehere82]

The human ear is a wonderful device made for collecting and directing sound waves from directly in front of you and directly behind you allowing you to perceive 3 dimensional spacial positions. High frequencies are too hard to determine position without using an aid of some sort.

You can make a crude position locator by cutting a 3' length of rubber tubing which you can listen through and probe different areas on the engine for the source of the sound.

The most likely sources would be a belt, water pump shaft, power steering pump shaft, A/C compressor shaft or clutch, alternator shaft, or a Vacuum line. Since you say it sounds like it comes from the air cleaner, I would look at the vacuum lines first.

 

[GerryLP]

Jeremy,

Look into Heidi's good suggestions before proceding. A lot of these components can cause a high pitch sound. Try belt dressing on the pulley belts while it is running. This will work to quite them down quickly. The local auto parts should have some belt dressing spray. Check the air pump. I had it freeze-up on my after a long time idling in traffic. Loosen and remove the A/C compressor belt to check if the compressor bearings may be causing the problem. The water pump could be causing the sound. Check the weep hole for signs of leakage. Check the fan for looseness or wobbliness. If the water pump bearings are gone, then this will make the shaft that holds the fan wobble. The bubbling in the fuel filter could be air. Perhaps the fuel pump is failing (however, I have never had a fuel pump fail on me).

However, if it turns out that none of the pulley-driven components are causing the high pitch sound, AND if it is time to change the oil, then I suggest that you place a piece of cheese cloth in such a way to catch what may come out of the drain, and drain the engine oil. Sometimes a spun bearing will make loud high pitch sounds. After a while, the sound turns into a clanking-type sound from the oversizing of the bearing. Cut the old filter open with a hacksaw to check for metal particles inside. The particles, if any, will be trapped in the filter pleats. This however should be your last resource. Check the components first.

 

[silver 80]

Do you have any of the smog items still intact? might be the air pump.
tom

 

[Ludigdrums]

Thanks for all your replies so far!

I have no smog equipment, so that eliminates the air pump. It's also not a belt, as they are brand new, and that's not the sound anyway.

It sounds like a circular saw cutting through wood. Not quite as loud.

I have a feeling like someone said that it might be the water pump. However the fan still moves freely.

Another thing about the sound...as I give it more gas the sounds pitch decreases until it seemingly goes away. It also does not matter which gear I'm in.

Again, all temps and fluid levels are fine. Performance also seems fine. I just drove home from Jersey to New York...about 1 hr drive....no problems, just that annoying sound.

Any other suggestions?

Thanks as always!

- Jeremy

 

[Vettehead Mikey]

It's also not a belt, as they are brand new, and that's not the sound anyway.

It sounds like a circular saw cutting through wood. Not quite as loud.

Still sounds like a loose fan belt to me. Remove them one at a time till you locate which one is making the sound.

 

[78SilvAnniv]

We recently replaced my water pump and after installation we had a screaming belt noise. Kenny would spray belt dressing and the sound would go away but would return after a few minutes. We found out that the problem was a rough spot on one of the belt edges. A mechanic friend who did some work for us had not replaced the correct spacers for our application and the belt was out of alignment just a bit. Kenny swore he was going to do all of the work himself to avoid problems like these...

The water pump also gave us fits because the parts house first gave us the incorrect one and the bell shaped pulley that fit over it was rubbing on the pump housing. TERRIBLE screaming sound! ...and then we had to remove that wp and replace it (yet again) with the correct one.
Heidi

 

[wishuwerehere82]

Thanks for all your replies so far!


I have a feeling like someone said that it might be the water pump. However the fan still moves freely.

The fan is de-coupled from the pump shaft by a clutch which is thermostaticaly controlled, so the fan will turn even if the pump is not rotating. Loosen the belt and try lifting the shaft. If the shaft moves up and down the bearings are shot.

Pete.

 

[Ludigdrums]

Thanks again for your replies. I tried the belt dressing on all belts and it made no difference whatsoever.

I did some more listening, and narrowed the sound to the carburetor on the passengers side of the engine.

GerryLP...do you think it still might be a spun bearing givin the other characteristics of the sound (ie: pitch goes down with rpm increase) This seems exact opposite to what you'd expect the sound to do. Usually, the faster something spins/moves, the higher the pitch of the sound.

What's weird is that this sound came from nowhere and about an hour into my drive. Since then, it's happened right from a cold start (which rules out anything heat related)

Keep 'em coming!

Thanks!

- Jeremy

 

[Ludigdrums]

Thanks Pete...I will try that. I guess I was saying that it wasn't seized...which I've had happen on my '87 Monte. Started sounding like a prop plane!

If it turns out to be the water pump, I'd be surprised because it's not that old.

Also, wouldn't my temps be affected if the water pump was messed up?

Thanks again!

- Jeremy

 

[wishuwerehere82]

Bad bearings wouldn't cause it to stop pumping, but it might come loose. My buddy bored a nice 20" hole through his radiator with the fan when the water pump bearings let loose on his '69 Z28.:cry

 

[jdp6000]

I would also try pouring water on the belts just to eliminate that as the cause.

You do have a smog pump...correct?One other possibility is the one way valve that connects to the small copper lines that go into the exaust manifolds. The air pump is suppose to send cooler air through that and the air is only suppose to travel one way. They do eventually go. If air is going the other way because of a small leak it could cause the sound you refer to. They are only about $15. If it is the cause be careful removing them, use two wrenches, you dont want to twist those copper pipes.

Jim

 

[brusso]

I would also try pouring water on the belts just to eliminate that as the cause.

You do have a smog pump...correct?One other possibility is the one way valve that connects to the small copper lines that go into the exaust manifolds. The air pump is suppose to send cooler air through that and the air is only suppose to travel one way. They do eventually go. If air is going the other way because of a small leak it could cause the sound you refer to. They are only about $15. If it is the cause be careful removing them, use two wrenches, you dont want to twist those copper pipes.

Jim

I think that it is called the "reed" valve. When I looked under the hood one day and noticed that the A.I.R. pump was removed, I heard a similar sound coming from that valve. The next time I looked under the hood, I noticed that someone had put true duels without cats on the car and removed all of that tubing you mentioned.

 

[GerryLP]

Thanks again for your replies. I tried the belt dressing on all belts and it made no difference whatsoever.

I did some more listening, and narrowed the sound to the carburetor on the passengers side of the engine.

GerryLP...do you think it still might be a spun bearing givin the other characteristics of the sound (ie: pitch goes down with rpm increase) This seems exact opposite to what you'd expect the sound to do. Usually, the faster something spins/moves, the higher the pitch of the sound.

What's weird is that this sound came from nowhere and about an hour into my drive. Since then, it's happened right from a cold start (which rules out anything heat related)

Keep 'em coming!

Thanks!

- Jeremy

I am not sure how long you have had the car running with the noise, but a spund bearing turns relatively quickly into a clanking type of sound. The bearing while spining will get larger (or the journal smaller), so if you had had the noise a long time, the likelyhood, it would seem, would diminish.

How is the sound relativve to load? Does it change?

GerryLP:cool

 

[78SilvAnniv]

I did some more listening, and narrowed the sound to the carburetor on the passengers side of the engine.

Check all of your vaccum lines that attach to the carburator, reference a book if needed. I had forgotten that after we got the 78 up and going that I had trouble one day with a bad idle and a loud whistling noise. It turned out to be (sorry, girl auto description coming up) the thing that pops into the top of the valve cover and connects with a piece of hose to the front of the carb.
Heidi

 

[Ludigdrums]

Thanks everybody...I found where it's coming from. I have a Holly 1850-4 carb w/elect. choke. The sound is coming from the pass. side behind the elec. choke. I sprayed water there and the sound changed. I still don't know exactly what it could be.

I disconnected the wires to the choke and there was no change. The only thing I did in that area recently was lube the choke mechanism with some white lithium grease. Could that have gotten in the wrong place and be causing the sound?

Heidi...I really enjoyed your 'girl auto description' I give many of those too

So, NOW what do we think?

Thanks!

- Jeremy

 

[wishuwerehere82]

Sounds like a gasket on your choke or your carb body.

Milkin machine,,

 

[Ludigdrums]

....And the winner is...

GMJUNKIE!!!

Thank you sooo much. That's all it was....just tightened a couple of screws and noise went bye bye!

Thanks to all of you for all of those great suggestions. You made my day!

Thanks again....yet another case solved!

- Jeremy

 

[wishuwerehere82]

Nice going GM Junkie!