Date: Wed, 29 Nov 2006 21:49:26 +0000 From: Eeyore <rabbitsfriendsandrelationsnospamail.com> Subject: Re: Terrible Screaming Noise
Fred W wrote: > Eeyore wrote: > > > > danielakers007nospamail.com wrote: > > > > > >>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. > > > > > > It's belt tension. > > > > Rubber *expands* when it's cold so the belt loosens and slips a bit causing the > > squealing. > > > > 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. http://scifun.chem.wisc.edu/HOMEEXPTS/rubberband.html When rubber is heated it behaves differently than most familiar materials. Graham
