Terrible Screaming Noise

I recently purchased a 1987 Saab 900, 4 door, normally aspirated. I shut it off coming home from work (it was a pretty cold night, but not below 30f I'd say) The next day I started it up and it made a incredibly loud screaming noise (one could say squealing as well). I checked the condition of the belts, they all apear fine, I didn't check the tension though... It seems the noise is coming from the front of the engine, which has me scared since all the moving parts up there are expensive. A few notes about the noise: it makes it wether in gear or not, makes it whether the clutch is engaged or not, and there seems to be no change in loudness or pitch of the noise in any change in the above conditions.

PLEASE tell me it's just water on the belts, I live in Oregon, so it's VERY wet here. Any help would be greatly appreciated, as I am only well versed in the workings of the Chevy 350, which the SAAB is, obviously, very different.

Reply to
danielakers007
Loading thread data ...

Reply to
yaofeng

So just drive it some and see how it goes perhaps?

Reply to
danielakers007

It's belt tension.

Rubber *expands* when it's cold so the belt loosens and slips a bit causing the squealing.

Graham

Reply to
Eeyore

Are you sure about that??

Reply to
Nasty Bob

I'm afraid not. Rubber has to follow the same rule as all other matter in the universe and *contracts* when cooled, expanding when heated. The obvious exception being when liquids change state and become a solid some do expand.

I've always thought that the reason for the squealing is that the rubber is *harder* when cold and therefore has less grip on the pulleys. That and the alternator load is the highest right after starting the car, so more apt top slip then.

Reply to
Fred W

There is one other exception: Water expands when cooled below 4 degrees C. Due to this effect lakes freeze at the surface and we can go skating!

Reply to
th

in article snipped-for-privacy@n67g2000cwd.googlegroups.com, snipped-for-privacy@hotmail.com at snipped-for-privacy@hotmail.com wrote on 29/11/2006

00:07:

If it stops after, say, 100 yards or less, it's most likely just some damp that's got under the alternator belt.

On our C900s (1987 and 1989), the alternator belt can be tightened by simply tightening the nut on the swing arm. Locate the brake booster on the LHS of the engine bay, by the firewall. Look at the belt just next to it, but further towards the middle of the car. That's the one ... See the long thread and the nut? Just tighten that one a little.

Better still, slacken it off, buy a new alternator belt and tighten it up, so that there is only 0.5cm "give" in the belt when pressed.

HTH, good luck guys ... Come back if that's not the issue.

Paul

1989 900 Turbo S
formatting link
Reply to
Paul Halliday

It cracks up engine blocks too...

Reply to
MH

Ooops!

Reply to
Greg Farris

This is true - though not the only known negative temperature expansion coefficient.

Due to which effect? Wouldn't that be more closely related to the fact that water becomes a solid at 0°C?

GF

PS - I do agree with the others - the screaming noise has a very high probability of coming from the belt, and the humidity you mention could indeed be related. As others say - drive it a bit and see what happens. Secondly, tighten the belt a bit and see what happens. Finally (as mentioned, and good advice) just replace it.

After all, what's the worst that could happen? The thing could catch fire and burn to a crisp so fast you cannot even get out! But far more likely you'd have plenty of time to get out and watch it burn to a crisp; This would save you the cost of replacing the alternator belt!

(sorry - couldn't resist. It's probably a belt and nothing serious).

GF

Reply to
Greg Farris

You are partly right, it's a combination of two effects:

1) if the solid wouldn't have expanded but become more dense than the water the ice would sink.

2) if the 0°C water would be the most dense it would also sink to the bottom of the lake and the entire lake water must reach 0°C before ice formation can start. Then just very shallow lakes would freeze during winter.

Reply to
th

It's the only substance that does AFAIK.

Odd one that.

Graham

Reply to
Eeyore

100%. Not sure about synthetics.

Here's a neat trick. Find a rubber band and stretch it quickly while keeping a free finger on it. It gets *cold* as you stretch it.

Graham

Reply to
Eeyore

formatting link
When rubber is heated it behaves differently than most familiar materials.

Graham

Reply to
Eeyore

You're on crack

Reply to
Fred W

It is to do with the hydrogen bonding in water, or at least it is over here?

Reply to
Richard Sutherland-Smith

Just try it. I discovered that as a kid btw. Rubber has some very curious properties. It gets surprisingly cold when you stretch it.

Graham

Reply to
Eeyore

formatting link

Reply to
Greg Farris

Reply to
Rod H

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.