A bit of a brake mystery

I have a noise that happens ONLY in cool or cold weather, after the
car has been sitting for hours in the cold or cool. And it completely
disappears after the first two or three brakings, with everything
completely fine afterwards. This is a metal/metal type of scraping
sound in the front left wheel area. This is the deal:

I start the car and drive down a small hill, stopping at the bottom.
There is no noise until just before the wheels stop rolling; IOW
there is no sound when I first apply the brakes. Lately, I've noticed
the added sound of a kind of grindy whine (that varies with engine
RPM) that comes AFTER I let off the brake pedal (for example,
if I put the car in neutral and rev the engine a little, the whine
varies with with engine speed). Sometimes now also, the grinding
scraping noise can come after letting off pedal for a short time.

An important fact to add is that I replaced both front rotors and
both pairs of pads on the front yesterday; everything is nice and
new as far as that goes, and I just knew that this would solve the
problem, but it hasn't. This would of course have to be a caliper
problem, yes? But I was just working all in that area yesterday
and didn't see a thing wrong anywhere. BTW, this is a 1998 323
coupe with about 74k miles. FWIW, the car also has AST and ABS.
Any ideas? TIA!

wrote:
> I have a noise that happens ONLY in cool or cold weather, after the
> car has been sitting for hours in the cold or cool. And it completely
> disappears after the first two or three brakings, with everything
> completely fine afterwards. This is a metal/metal type of scraping
> sound in the front left wheel area. This is the deal:
>
> I start the car and drive down a small hill, stopping at the bottom.
> There is no noise until just before the wheels stop rolling; IOW
> there is no sound when I first apply the brakes. Lately, I've noticed
> the added sound of a kind of grindy whine (that varies with engine
> RPM) that comes AFTER I let off the brake pedal (for example,
> if I put the car in neutral and rev the engine a little, the whine
> varies with with engine speed). Sometimes now also, the grinding
> scraping noise can come after letting off pedal for a short time.
>
> An important fact to add is that I replaced both front rotors and
> both pairs of pads on the front yesterday; everything is nice and
> new as far as that goes, and I just knew that this would solve the
> problem, but it hasn't. This would of course have to be a caliper
> problem, yes? But I was just working all in that area yesterday
> and didn't see a thing wrong anywhere. BTW, this is a 1998 323
> coupe with about 74k miles. FWIW, the car also has AST and ABS.
> Any ideas? TIA!
>
I would take a look at the brake booster; check the fluid level and the
belt tension.

Bob wrote:

> I would take a look at the brake booster; check the fluid level and
the
> belt tension.

The more I think about it, the more I think it's not related
to the brake system at all. How could it be? I think it's
a bad pulley that somehow does a good job of imitating a
brake problem. The sound is very similar, and it does it
when coming to a stop downhill, but it turns out that it
also does it without braking too.