I noticed a rattle in my engine about 1000 miles ago. It sounds most like the rattle you get when you shake a can of spray paint, although it's slightly heavier sounding - as if the wall of the paint can were thicker and the ball inside heavier.

The noise goes away if you increase RPMs and when the motor warms up. It can't be heard from inside the car and can be barely heard with the hood closed.

Standing in front of the car it sounds like it's coming from the timing cover. I listened with a hose to my ear and it sounds like it is coming from the PS pump - there's no noise through the hose from the timing cover area.

It's almost not a rhythmic noise ie. it increases with engine speed but doesn't have the direct RPM matching of, say, a valve tick or piston slap.

The PS pump pulley is fine. The water pump pulley has the tiniest looseness to it. AC pulleys and alternator look fine; main harmonic pulley looks fine. No loose brackets, bolts.

Because of the metallic nature of the sound I suspect an engine noise. It doesn't sound like a valve tick.

The noise is roughly coincident with an oil change (10w30 at w/ 3500 miles to 10w30 - both fossil oils). Runs & drives well and no change with the noise.

I'm going out now with a hose to check on the cold engine again.

Any suggestions?

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85-92 240s/ 245s - parts cars & drivers