'91 DeVille....Funny Noises

So the situation is this. When I'm stopped or moving really slowly, my engine makes a strange kind of grinding sound. I've never heard it when I'm moving above...say...10 mph or so. It's a fairly rhythmic noise too, has a very definite beat to it if you will. Anybody have any suggestions? I've pored over my Haynes manual and I can't find anything in there.

Interesting problem. I would first look under the hood with the engine running to see if it is an alternator bearing or something like that which might not be noticable when engine speed it up. Also look for loose or cracked vacuum hoses. Maybe somthing loose that blows out of the way when you drive and flops down at low speed rubbing on something. Also check the serpentine belt for cracks or something.

Then I'd look at the wheel bearings and brakes.

Good luck! Maybe someone else will have other ideas.

I had the same noise and it turned out to be a loose alternator pully.