Slapping Injector on '80 300SD

On my 1980 300SD the #5 injector has been slapping from the first day I completed the overhaul of the engine. I have replaced the timing device and the injector itself. The injector slapping only occurs at idle or near idle. As soon as the engine moves past this regime, the slapping stops. On cold mornings the slapping also is much less detectable until the engine warms up. I am suspecting the injector pump. I have had this injector pump overhauled but I suspect that the satisfactory cold operation prevented any detection of the problem. Are there any suggestions regarding the cause of this continual injector slapping? What in the pump could be causing this?

That is a very good question.

[CJ]

Slapping or nailing? If it is is slapping, please expalin this to me, as I have never heard of injectors slapping.

[CJ]

I think the term that both of us iare referring to is nailing.

[Aaron]

Pour a bottle of Red Line Diesel Catalyst in the tank. That should take care of the nailing.

[stevebfl]

I have listened to it, one way or other, for almost thirty years. I think it might be a multiple personallity.

For years I heard pinging type sounds in 300Ds (non-turbo)in the coast situation. Always from cars that got tremendous mileage. I always thought it had something to do with being too lean, but it could have been a timimg thing. I haven't heard one in years; maybe it was the fuel and the leaness??

The noise seams to occur on 603 type motors when the pump elements leak internally??? Maybe a lean condition.

Injectors have caused the overall knocking sounds of every description. Poor spray patterns give a leaner useful mixture. Restricted injectors the same.

Diesel knocking, pinging, nailing, etc. seam to me to be caused by all manner and effect of separate lean mixtures and/or timing.

BTW compression can cause noises due to incomplete combustion and preignition if too high.

A decarbonizing injector cleaner (such as Aaron mentioned) can inprove at least four of these factors