injector sealing washers
 

What is the purpose of the sealing washers?
I don't have them in my '80 240D -- I did not install them when I rebuilt the engine, and it runs perfect. Will any damage result?
The washers are installed in my '79 300CD I rebuilt, and I am having problems with "nailing" or "pre-ignition" noise.
What would it hurt to remove them from the CD and would it help the noise?

Thanks

I'm not sure what leaving the injector seal out will do to a Benz with a cast iron head over time, but with the VW Rabbit type engines (Aluminum head-Same type of injector ) I remember it being said that it would ruin the head over time.
As for nailing, TheBenzBin web site has a info page about this...it is caused by use of the injector over time(about 100k) which weakens the spring in the injector thus injecting fuel too soon into the cylinder, and if bad enough, trying to drive the piston back the wrong direction. Very bad for the engine!!!
I've had an engine apart that I suspect had this problem...it broke the piston and multi-cracked the head in the cylinder that apparently had the bad injector.
I think anyone with this problem needs to remove their injectors and get them tested ASAP!

that "sealing washer" is actually a heat shield, which prevents damage to the nozzle tip face from the extreme heat of combustion. all mbz diesel engines used these. damage to the nozzle tip face will be slow, but it will eorrode the nozzle tip face over time. i would advise getting a set installed in your 240, also, replace them everytime you remove a nozzle. they seal when "mashed" into the prechamber, so once "mashed" or "compressed" they will not seal properly again. be sure to clean the chamber and face of the nozzle before reassembly to promote good sealing.

If you look at how the injector fits into the prechamber, there is no heat transfer path for the injector nozzle body to the head. Thus, the washer with the pattern cut into it, which is to ensure the nozzle body surface at the bottom of the injector contacts the raised ring at the inside diameter and then is allowed to conduct heat away and out to the prechamber body.

I am not certain but I also think this part helps keep combustion junk out of the injector to prechamber threaded bore. Since the injector bottoms on these seals/heat shields and there are no other sealing rings or sealing devices it seems they must also perform that function as well.

Overall I think it is not wise to run without all the parts the engineers included in the engine design. I would put them back in and just figure I might have been lucky nothing bad happened that I have noticed, so far. Good Luck, Jim