Hello all. The girlfriend has a 1997 Saab 900 Turbo Talladega and I've
noticed some peculiar noises that I wondered if you guys could help me
identify. The first one is engine related: Following a period of
acceleration, if the car is left in gear and the gas pedal released,
there is a rhythmic "shh shh shh shh" noise. It's not extremely loud,
but it is perfectly audible, even with the windows closed. I guess it
sounds like something turbo related. Is there a wastegate/ dump valve
on these cars that could account for the noise, or is it likely to be
a leak in the turbo plumbing? Incidentally, the car is still very
rapid, so doesn't seem to be suffering performance-wise.
The other noise that the car has just started making is a "clunk" that
sounds similar to cars I've owned/driven where one or more rubber
bushes in the suspension have perished. The clunk occurs maybe once
every 2 miles or so, but I can't say for sure whether it's associated
with bumpy road surfaces. I also can't really identify where on the
car the noise is coming from, so can anyone tell me if a particular
bush (or bushes) are prone to going on these cars?

Thanks in advance for any help/ advice, Jim.

Thanks to Mohandes for the suggestion that it may be the timing chain,
but I should have mentioned in my original post that the car has only
done 50,000 miles, so it seems a little premature for it to be worn.


Regards, Jim

Jim Walsh wrote:
There is both a wastegate and a dump valve, but I don't think
either is making the noise you describe. The dump valve makes
one single "Pshh", which you hear when you release the throttle
under high boost (e.g. when changing gear).

Leaks in turbo plumbing tend to present themselves under boost,
not on overrun.

My short answer is don't worry about it. If something's going to
break, you'll find out about it when it does. There's probably
nothing wrong.



Could be anything. Once again, leave it until you have more
definite symptoms to work with.

--
Grunff