A while back, I stated that I thought I had ruined my turbo by running too low on oil for a while (DOHHH!!!).

For the last few months, a noise has been gradually been getting louder with a rough and grating sound that sounded a bit like having a bad exhaust manifold. I couldn't find any evidence of air pressure shooting out so that wasn't it.

A couple of weeks ago, the noise went terminal. Just a hellacious racket. Odd thing was the noise would recede entirely when I'd accelerate hard. As soon as I backed off on the pedal or went down to idle, the noise would come back very loud.

Using my stethoscope, I thought I heard the noise coming through the turbo. I'm wondering if I was just hearing the racket vibrate through the turbo housing giving the impression that the problem was in the turbo.

I'm hoping someone out there has enough experience with the 617 to recognize these symptoms.

It almost sounds like the injector noise mulitplied by 10 with some rough scraping noise thrown in.

I took the turbo off last night and used my compressor to spin the fan. Smooth as could be, also feels nice to the touch, no play at all. I wired a couple of cans to catch oil spurting out the open turbo socket and fired it up for about 10 seconds. Noise still there.

So I'm thinking injector pump or something in the valve train. Weird thing is, even when it was making the loudest racket, no noticeable loss of power.

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1986 300SDL, 362K
1984 300D, 138K