Hey All,
My 87 300D (OM603.96) just picked up a horrible knocking/rumbling noise...
the other day, I was low on gas and time and went to a usually reliable
station and picked up a few gallons, drove about 50 miles, then noticed an
occasional sound like rocks rumbling around in the engine. It was present
at idle but I couldn't hear it when the revs increased. Tried filling up
with a dependable fuel source (Arco ECD-1) which was about 15 gallons, and
was en route to do an italian tune-up when the noise got worse (about 2
miles from the fill up). Sounded like there were more rocks, and there was
a whirring/grinding noise that was RPM dependant as well. Got it home and
let it cool down and restarted it, the knocking is back to how it was when
it first appeared -- random, like rocks in a cylinder or something.
Car has full power, no smoke, no ill effects whatsoever besides the noise.
202k mi running Mobil 1 synthetic. Head is possibly cracked but not very
bad, and the car has been overheated once in my ownership. Have cracked all
of the injectors and they all hurt the idle but don't take the noise away.
The noise sounds like its coming from the underside of the engine, near the
oil pan area or just behind. Prefilter has some small debris but nothing
big nor numerous. Pulled the primary filter, dumped it, and did the long
crank to refill it -- cranking sounds completley normal (none of the noise).
Catalyst was replaced before I bought the car and the EGR system has been
disabled.
Any ideas whats going on, or how to troubleshoot?
Thanks!
Mike