noise coming from under valve cover, need help diagnosing...
 

Guys,


*EDIT* I have updated the description with more details.

On the '85 there is a rhythmic sort of chugging sound at around 1200-1800 rpm under load. almost sounds like an exhaust leak, but I don't think it is.

The noise has been there for the past 700 miles, and was there when purchased. decided to let it go at first and run a few tanks of new fuel (car had sat for two years) through before coming to any conclusions.

the noise:
- is not present at idle (normal diesel clatter)
- appears at 1200-1800 rpm, especially under load
- also appears at same RPM's while pressing down brake and accelerator simultaneously to load down without moving, or when just when revving in neutral
- seems about 1/5 of RPM speed
- is not loud enough to hear over the blower on high
- sound goes away above 2000rpm, runs great on highway

the noise is coming from under the mercedes symbol on the valve cover. what could it be?

what can i check when i take the valve cover off? what could be loose?

Thanks,
dd

Make sure manifold bolts are tight,they can get loose.Also if been that way a long time,gasket job may be needed.EGR can stick and leak I've heard.

if it was an exhaust leak, wouldn't it stay when i was on the highway?

EGR seems like a possibility, i like that...but would it be rhythmic?

ill check the manifold bolts.

thanks for ideas. i need to get away from thinking bad thoughts, like rods and bearings and internals :D

updated the first post with more description...