Injector / PreChamber Question (after searching)
 

I apologize if there has been a thread on this (couldn't find one using the search)

I rebuilt my set of injectors a little while back. A local owner found out I 'tinker' with these and asked me to rebuild and pop-test his injectors.

240D 283,000 Miles

When I did my injectors there was very little build up (carbon, oil) beyond the tip of the injector.

The 283,000mile 240D had so much oil, carbon on them it was difficult to remove them from the pre-chamber.

My question:

Is there/could there be a problem with the pre-chamber if there is this much build up? Could it be that the crush washer is just not sealing properly and a new set of washers will take care of it? Is there something else?

I was a gasser mechanic for years. The rebuild on my injectors went pretty much by the book (had to re-test one injector five times to get the pop pressure right) but didn't want to rebuild these injectors, install them with new washers and have this guy have problems in a short amount of time.

I do mechanical work (usually on gassers) on the side for extra money. I want to make sure everything is right if I'm going to do this.

Comments?

You would be able to see any defects in the PC sealing surface if that was the case. I have seen this same thing on injector nozzles. They become blue and caked in a film of flaky carbon, making the nozzles a PIA to remove from the body.

As long as the PC surface is clean and does not look irregular, the new nozzles should seal on the heat shields just fine.

Thank you.

Leaving work now, was just waiting for a reply.

thanks again.

I forgot to mention that you are correct. It is due to a poor seal at the heat shield, most likely from being reused too many times or poor alignment with a pitted nozzle surface.

I can remember some Injectors that I pulled from the Junk Yare where the Metal on the Injector Nozzle had eroded/burned past the sealing area of the Heat shield.

It is also possible that at some time Oil leaked from a bad Valve cover gasket and seeped in between the threads of the Injector and cooked there over the years.
Finally someone changed the Valve Cover Gasket and cleaned off the block; but that old Oil would remain down there.