E300 glow plug success!
 

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
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Carbon from #1
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All 6 out, note the corrosion on the body of #6! That bastard took 2 hours to get out!
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New plug dressed and ready for action
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Clean IM!
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Time to whore the old girl a little
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I did one not long ago and there was one that was broken off that the previous mechanic had taken the wire and just bailing wired it to a place where it would be grounded. I decided to try to tackle removal of the broken gp and unscrewed it most of the way with the engine running:). Worked out great.

I've done a half dozen glow plug jobs on older Mercs without incident, but with all of the horror stories surrounding the 606 I was a little apprehensive. Patience is key.

Patience really seems to be the key and not putting too much torque on anything while attempting to remove it. I used the torque wrench set a couple NM higher to get mine started, just to help ensure I was not putting too much on it.

Glad it worked out. I think I will now take mine out periodically as it really was not that big of a deal.

on the three that have corrosion, I'd get a rifle bore brush, and clean the sleeve the GP fits in. get that sucker corrosion free!
use a PLASTIC bore brush, not a steel one!!! you DON"T want to deform the aluminum!!!

When I dropped our w210 off to have them done (I was way too skeered to do it myself after reading the horror stories on here) I dropped it off with a new full can of deep creep, a new tube of anti-sieze compund, and all new Bosch GPs. When I picked it up- they told me they "pre-sprayed" them as I requested and let the deep creep soak, and then briefly warmed it up- and then... used a set of vice grips and get em all out (gasp). They all came out with no probs.

To me it sounds like everyone has had the engine up to operating temp, then prelubed the plugs for removal, after removal cleaned the bore and added neversieze to the plugs before installation and have alot of time and patience. Sounds like thats what I need to do so I dont break and gp's.
Thanks for all the good advice and tips.

I wish I was as lucky as you. When I attempted to remove mine, 2 of them broke off. Right now I'm in the middle of drilling them out. Already bought and used the glow plug reamer on the other 4 plugs and put anti seize on new Bosch glow plugs...

I have had many glow plugs swapped out over the years, what would you all think of removing the injectors , spray , or pour wd-40 into the cylinders , crank it, let it sit ? add more wd crank it , then carefully remove glow plugs . with glow plugs out , crank to clean out residue , install injectors, plugs , fire it up ? I know it would be a mess , but remove fuel filter , install new one when done ? This should clean out carbon from the inside ?

WD-40 & Glow Plugs 606
 

What about removing the injector , adding wd-40 into the cylinder , cranking it with no compression < clean it from the inside ? When the glow plugs are out , crank , let sit overnight wd will evaporate , connect everything , new fuel filter , start her up ?

Naw, if I went that route, I would do one cyl at a time. Bring it up to TDC and then pour the solvent in from the top and let it sit overnight.

BTW, so the last time I did mine I used a torque wrench , as I tend to over horse and break things, and VOILIA! two broke anyway. Right at the threads. My guess, at least one was already given stress risers at that radius by someone over tightening them on the way in.

I punted and let a mechanic at $60 a hour whittle the broke GPs out of there. He did. He made up a tool that pulled them out, after drilling away the threaded area.