I pretend that it's the Chevy/Ford/GMC truck in front of me that almost everyone where I live seems to drive.

ok, so it's possible (I thought it might be, just wanted to check) - how about tools, anyone?

I might have a similar problem as yours.

Just wondering does the noise change depending on your engine speed (RPM)? Higher pitched? or does it stay constant?

Mine went up and down with engine rpm.

The bearing on the air pump also went out at a different time, and made the same horrible screeching noise.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

yup, same problem here - I believe it's possible to replace just the bearing, not the entire air pump (I hope so, as remanufactured air pumps are $600+)... can that be done with the radiator in place too? I believe it's in a fairly akward place tucked in close to the exhaust manifold...

Yep, the dealer sells an air pump rebuild kit, which is basically the bearing assembly, and it costs about $200-ish, plus labor to install.

The air pump is removed from the car, the bearing is replaced on the bench, and its reinstalled in the car.

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

I tested this last night - the noise stays the same, but the drumming sounds increase in frequency as the rpm's rise.