My '90 is making a grinding/grating noise at the distributor or water pump. The problem is I can't tell where it is coming from. I have had the water pump and distributor out and both are in good working order, as is the timing belt idler.
Neither exhibit any reason for the noise.
An additional complication is that the noise does not exist when the engine is cold - just after start-up. The noise appears after the engine warms up.

Any ideas?? This noise really is embarassing at stop lights, etc.