: Northster Squeel/Whistle



thebigtomster
10-31-05, 12:02 PM
My first post. After my engine begins warming up I sometimes, much more recently, get an ear piercing speed dependant squeel/whistle from the passenger/front of the engine. It seems to be coming from between the power steering pump and the firewall. I can't get any closer because the engine is running and at that short range the noise is physically disruptive, i.e. it hurts. When I turn the engine off the noise seems to linger slightly after the engine has stopped. It never does it when cold. It gets worse the longer it idles.
Please Help.
I love my 94 SLS.

mcowden
10-31-05, 12:26 PM
My first post. After my engine begins warming up I sometimes, much more recently, get an ear piercing speed dependant squeel/whistle from the passenger/front of the engine. It seems to be coming from between the power steering pump and the firewall. I can't get any closer because the engine is running and at that short range the noise is physically disruptive, i.e. it hurts. When I turn the engine off the noise seems to linger slightly after the engine has stopped. It never does it when cold. It gets worse the longer it idles.
Please Help.
I love my 94 SLS.

When you say "speed dependent," are you talking about car speed dependent or engine speed dependent? Have you checked the pop-off valve on the passenger side of the intake? It could be not sealing properly and whistling with intake vacuum. How is your idle speed? Have you checked for codes?

Ranger
10-31-05, 12:36 PM
If it is not the pop off valve that Mcowden is talking about (which should cause a high idle if bleeding), then check all the vacuum lines including the vacuum reservoir under the battery tray. Sounds like a vacuum leak.

thebigtomster
10-31-05, 01:25 PM
It is engine speed dependant. The idle pulses slowley in park from about 600 to 850 RPM. No codes.Please explain "pop-off valve" further. What does it look like, is it like a pressure "circut breaker", can I reset it, where exactly is it?

You guys Rock!

powerglide
10-31-05, 02:22 PM
I've still got a high pithced whistel in mine....let me follow along with this post.

mcowden
10-31-05, 02:24 PM
It is engine speed dependant. The idle pulses slowley in park from about 600 to 850 RPM. No codes.Please explain "pop-off valve" further. What does it look like, is it like a pressure "circut breaker", can I reset it, where exactly is it?

You guys Rock!

It sounds exactly like a vacuum leak. Hard to tell if it's the pop-off valve, but it does sound like that. The valve is on the intake, kind of hard to see on the lower part of the intake cover on the passenger side. It's nestled in there down low. It's round and inset a bit. Its job in life is to relieve pressure in the intake if a backfire occurs. If it's not completely closed, it will leak some air and cause an erratic idle as you're describing and it can whistle. I'm not exactly sure how to fix it, but the intake cover will have to come off. I think it has a spring to keep it closed. Maybe the spring came off or the seal around the bore is worn or cracked or something. Someone else may be able to tell you more about how to fix the thing, or if you take the intake cover off, you might be able to figure it out just by looking at it.

If it looks like that valve is closed completely and the sound is not coming from there, you will have to pinpoint exactly where the sound comes from. Wear some ear plugs if you have to, but the sound is the source of the problem. It could just be a loose vacuum hose, maybe the PCV valve, grommet, or hose. The intake cover seal could be leaking as well. Pinpointing the sound exactly will lead you directly to the source of the problem. It's got to be a vacuum leak if it's engine speed dependent and your idle is erratic.

eldorado1
10-31-05, 03:33 PM
a 94 would not have the plastic intake, so it's not the "trap door".

It definately sounds like some kind of vacuum leak though. Maybe get some intake cleaner and start spraying around the top cover's gasket, and around the bottom of the intake. If your RPM drops in response to the spray or the squeak goes away, you'll have to replace that gasket.

Ranger
10-31-05, 05:13 PM
Also a stethescope or length of rubber hose to your are would act much like a geiger counter in locating it. It would probably lead you to it in a minute.

Eldyfig
11-30-05, 08:37 PM
TheBigTomster,

Did you ever find the cause of your squeel? I am curious.

chevelle
11-30-05, 11:59 PM
My first post. After my engine begins warming up I sometimes, much more recently, get an ear piercing speed dependant squeel/whistle from the passenger/front of the engine. It seems to be coming from between the power steering pump and the firewall. I can't get any closer because the engine is running and at that short range the noise is physically disruptive, i.e. it hurts. When I turn the engine off the noise seems to linger slightly after the engine has stopped. It never does it when cold. It gets worse the longer it idles.
Please Help.
I love my 94 SLS.


There is no pop off valve on the intake of a 94.....

This does not sound like a vacuum leak to me.

It sounds like the bearing in the belt tensioner has dried out and is failing.

Try loosening the serpentine accessory drive belt tensioner so that the belt stops moving and see if the noise goes away. It if does then the noise is related to one of the pulleys in the accessory drive. Most likely candidate is the idler pulley on the belt tensioner.

Eldyfig
12-01-05, 12:25 AM
When I turn the engine off the noise seems to linger slightly after the engine has stopped.


Still think it is a bearing? I would think if it was a bearing, the sound would stop when the engine is stopped.

chevelle
12-02-05, 12:29 AM
Still think it is a bearing? I would think if it was a bearing, the sound would stop when the engine is stopped.


Yes I do. The noise is obviously loud and annoying which is just not explained by any sort of vacuum leak I have ever heard. Besides, he says thta the noise SEEMS to continue slightly when the engine is turned off. He is not sure...possibly due to the noise being loud and possibly due to the fact that the engine may rotate a slight bit after he perceives that the key is turned off. I'll still bet on the bearing, yes.

Eldyfig
12-02-05, 02:17 AM
You turn that key to off, that engine isn't going to rotate more than a second. The kinetic energy is gone quick.

I'd go with vacuum leak specifically because he said it lingers after the engine is off. I doubt we will find out for sure what it was. He came, got some answers, fixed his problem possibly. We might hear back from him when another problem arises.

samm
12-02-05, 02:10 PM
yes but he didn't say the noise lingers for more than a second now did he?
its all about possibilities...

chevelle
12-03-05, 12:16 AM
Just proposals and my opinion. I'll stick by it.

Unless he fixes it and posts back none of us will ever know what the real problem was.

BTW...if you watch the engine when the key is turned off it can sometimes stop and kick back or reverse rotate very slightly which will also continue any squeeking noises from the accessory drive as the load momentarily reverses if a bearing is bad.

Besides, have you ever looked at a vacuum gauge when the engine is turned off?? The vacuum disappears pretty darned quick also. Not enough residual vacuum to keep emitting a high pitched squeel for a period of time either.

Marshall
12-03-05, 02:25 PM
I had the same thing on my 94 Eldorado turned out to be the intake gasket.
A easy way to check it : while the engine is running, slightly loosen the bolts that hold the intake assy. down and then you can move the intake assy. around a little bit if this changes the sound then that is the problem. The intake gasket is made up of 2 strips of rubber bonded to a thin piece of stainless steel. The rubber (on mine at least) had debonded in a corner area and this created a very good whistle!! This may have been caused by over torqueing of the mounting bolts.
Hope this helps,
Marshall