My E300D has been in the shop for a couple of days now. First they found that the glow plug relay was bad...then 4 bad glow plugs.

So I told them to replace them...both of us knowing that it would be a tough job because of the carbon build up.

Bottom line is that they were able to remove 5 of 6 glow plugs. The 6th plug broke at the head but did not shear off (I'm having a hard time visualizing this myself). One option is to pull the head, another option is to leave it there. Interestingly this plug is one of the old ones that still works.

The owner of the shop called to explain the situation. He said there is a remote possibility that the compression of the engine could force the "guts" of the glow plug out...resulting in a very loud leak through the prechamber.

At this point I am having them put everything back together.