Well, I looked my 300SE up and down last night, and I am at a loss as to what could make that noise from the front end, even with the serpentine belt off.

Unless it's timing chain related, I'd still pull off the distributor and check that the back cover, the red plastic disc that "seals" to the back of the distributor cap hasn't broken or otherwise found itself scraping against the camshaft. There's also the camshaft seal on the timing cover, but I'm really grasping at straws here.

One thought I had was that your EGR is leaking and making an exhaust whistle, but I have to think you'd have located it if that were the case.

I mean, you took off the serpentine belt, right? What is left spinning after that? The cranksaft, the camshaft, the oil pump, the distributor, and that's pretty much it, no?

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-tp


1990 300SE "Corinne"- 145k daily driver - street modified differential - PARTING OUT OR SELLING SOON - PORTLAND OR. AREA - PM ME FOR DETAILS
1988 560SEL "Gunther"- 190K passes anything except a gas station
1997 S420 - 265k just bought it with a rebuilt trans. Lovely condition