Nailing sound on cold start
 

Just throwing this out for discussion. If I get some help on it, all the better.

1983 300D with 237K on the clock.

First cold start of the morning or after sitting 6+ hours, it sounds like one or two cylinders is pinging/hammering. Sound goes away after about a mile of driving or after the motor warms up a bit. Any ideas.

Before anyone asks, the glow plugs and relay are new and the problem occurred before the new glow plugs were put in. A diesel purge was also done and all filters changed with no improvement.

No idea on if the injectors were ever changed out so it is probably due for new nozzles.

Overall the car runs great, starts up instantly and idles smoothly. On the road she gets about 27 MPG at 60 MPH or so.....Just the nagging nailing sound at start up.

Glenn

http://www.youtube.com/watch?v=dseUEVVGsAw
Worth having a look at.

As I put my flame suit on, try running some diesel purge. Also, do you guys up there in WA get winter-grade diesel? Is this a newish issue?

before a purge, try an Italian tune up.
basically, get the car on the highway, and drop it into 2nd gear as you accelerate up the ramp TONS of smoke will billow out the tail pipe. hold it near 4K for about 30 seconds, then drop it up to 3rd and accelerate up as fast as you can and then let it shift up to D and drive normally.
do this twice then see how it runs.
it's best to do this after the car reaches full operating temp though.

Doing the Injector Cutout test would tell you if it is spacific Cylinders. Swapping good a good Injector with the suspected bad one would tell you if it is an Injector.
If it is an Injector and you have the Stock Type Injector Nozzles it could be that the drilled passages in the Nozzle Pintel are clogged with Carbon (see #14-#15) in the diagram.
All of mine were like that and most of the ones I pulled from the Junkyard were like that.
If both drilled holes are clogged I think it is unlikely a Purge will loosen it.