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On Mon, 26 Dec 1994 TONY.D.OAKLEY wrote:
Subject: no whine before its time....

>My '87 535is has a whine in the stereo system.  It has both alternator and
>ignition noise.

>The stereo is quiet just after it is turned on, in about 1 minute the whine
>begins.  The sound is independent of volume comtrol position, but does seem
>to worsen with higher outside temperature.  The sound comes and goes somewhat,
>perhaps related to other electrical devices being activated.

>One local BMW csar said it is a common problem with 'is' stereos and simply
>needed a Radio Shack noise filter, The local auto stereo lords say it is a
>defective head or amp, and is cheaper to replace than to repair.  These
>guys have always been honest and competent in the past.
>The racket is just too obnoxious to ignore.

>Anyone dealt with this?

>t.o.

   I don't claim to be a BMW czar, but I've owned a few BMW's (no is's
though) and none of them exhibited this noise. I find it hard to believe
this would be related to just is's since they are basically the same
as a 325i with the exception of suspension, aerodynamics and maybe some
interior cosmetics...

 First thing I'd check is the ground strap between the hood and the
radiator support. It's in the front near the hinge. If the strap is shot
or making a poor connection, noise will be transmitted from the engine
compartment to points beyond... This is a fairly common problem.

 Second thing I'd look for if the first one dosen't solve the problem is
the factory installed alternator noise filter. Most cars have them,
although I'm not positive that BMW does. Check the shop manual to see
where it is. Yours may be shot.

  Third, if the first two don't solve the problem, go for the radio
shack noise filter. I've used it in the past on non-BMW's with good
results. They used to offer two types. The cheaper one was just a large
capacitor which went from the power wire to ground. The better one
(which is the one I used) is an L-C circuit - a coil wired in series
with the power wire plus a large capacitor hanging off it to ground.
It's a cheap alternative to a whole new stereo system...

 Fourth, check your spark plug wires. They generally are shielded to
some degree to limit noise transmission. Perhaps yours are either
non-shielded performance type wires or are old and need to be replaced.

  Just my $.02 worth....


Ron Checca
'90 M3 Street
'88 M3 Track
'87 325es Road