I recently swapped out my '98 E300's original glow plugs. It took a total of 7 hours to work them out, but not one busted off in the head! I read somewhere on here the possible benefit of localized heat via removal when the engine is still hot, so I did just that. I also went a step further and plugged the block heater in while I was working to try and keep the temp up. 3 of the 6 came out without issue, while 1, 3 and 6 took a lot of finesse. Loosen 1 degree, spray deep creep penetrating fluid (my personal favorite), tighten, loosen exc. I was surprised at the lack of crud in the IM/ head for a car with 200k. The EGR has been bypassed for the last 100k and I've only used LubroMoly 5w-40. This is proof that the job can be done if you go slow and use all the "tricks". Also, ream those pre-chambers! I was really surprised at the amount of carbon in my engine compared to the 250K plus mile 603 & 617 powered cars I've owned. Kent at Mercedes-Source has the 606 reamer for under $60.

Reamer, new plug, old plug


Carbon from #1


All 6 out, note the corrosion on the body of #6! That bastard took 2 hours to get out!


New plug dressed and ready for action


Clean IM!


Time to whore the old girl a little