Intermittent nailing? Diagnosis and Opinions Please. - PeachParts Mercedes-Benz Forum

R Leo · #1 08-13-2003, 10:10 AM

OM617.952
1983 300TD
229,000+ miles

Occasionally I hear (from the descriptions here) what I'm assuming to be intermittent nailing.

I can only hear it happening at low engine speed (1000-1500 rpm) with a light, 'drifting' throttle. For example: coasting through a parking lot and slowly decelerating.

The sound is a sharp, almost metal to metal (clack-clack) sound that is repeated 4-8 times then quits. Sometimes, I can make the engine repeat the same sound 4-8 times if I speed up slightly and then gently decelerate again.

I never hear this sound at any other time and I cannot recreate this sound when running the car in the shop. Consequently, I have no way of telling which, if any, injector it is.

What do you think this is?

slowmoe · #2 08-13-2003, 01:14 PM

Have you done search on "nailing"yet. If not give it a shot. From what I have gathered you may want to try two things.

1) Run a bottle of Diesel Purge through the system directly from the can into the pump - not just in the tank.

2) Some have tried replacing injectors one at a time to see what one may be bad. However, whith what you are discribing, this may be hard to do.

I would start with the purge, especially if it has been a while since you have done it. I am in the habit of purging my cars every 30K. If this doesn't correct the problem - try one injector at a time. Good luck.

rickg · #3 08-13-2003, 01:48 PM

My SD had the same thing going on. It went away after our vacation. Must have cleaned out the systems doing 70 to 80mph for 1600 miles in a week. These engines must just get carboned and gooked up with lazy driving to and from work.