Snapped off GP, I think. W210
 

I have read all the broken glow plug threads I can find but I don't remember seeing this situation. I was removing #5 after easily replacing #4. 5 was taking a lot more pressure to loosen. I had used plenty of PB Blaster and I was working on a hot engine. Finally enough pressure was applied and I heard a snap and it appeared to come loose. I began backing it out, there was still significant resistance but the ratchet could be turned with one hand. I kept going and going but the plug was not backing out. Still resistance like it is, but it is not coming out. At that point I stopped and decided before I screw anything else up I would come here for advice on my next move. Is it snapped off and is this the normal failure mode?

I know from the other threads there are methods to drill/tap/etc and get the broken off plug out. But this is still one whole plug. Apparently it is separated above the threads as it won't back out. Where do I go from here?

PS: Pulling the head is not an option.

I've changed glow plugs twice on a w210 and haven't broken one yet. But I have had glow plugs make a fairly loud "poping" noise as they break free from the carbon buildup and/or the thread connection with the head. So if your plug is still intact, the threads are loose from the head, and its turning, my guess is that the plug isn't broken but its the carbon buildup that is holding it in. I would continue to spray penetrating oil, keep turning it, and gently attempt to pull it out. I prefer to use penetrating oil spray at this point rather than the PB Blaster because what you are really trying to do is to soften up and flush out some of the carbon build up around the plug so it can slide out.

David Roseman
Long Beach, Ca

Presuming it is not broken
 

Blast the heck out of hit and start screwing back in and out and take it pretty much all the way back in, blasting all the way. Hopefully this will migrate the PB further in and ease your fears of breaking it. And yes, hopefully David is correct and it is just the carbon buildup.

Thanks for the quick reply.

After closer inspection, unfortunately I have indeed broken it off. The attached pic shows where it is broken. Apparently the wiring/element is turning within the plug and causing the resistance to turning. I guess now I just follow the other threads unless someone else has a better suggestion:mad:

Can you compare it to the others to see if you have made it come out at all or not? It is possible to break them so the hex portion just spins free and does not unscrew from the hole...if that is the case then you are sunk.

If, on the other hand you have unscrewed it to the point where all that is holding it in is carbon then you ought to be able to see all or at least most of the threads outside the hole and you can just pull the plug out using vice grips or something like that.

Nevermind my prior post...you are indeed sunk.

Some have had luck drilling them out, some have had to resort to having the head pulled. Either way you need to do some homework before you destroy the head trying to extract it. Do some searching here and you will find all of the information you need to try and drill it out. Good luck.

Don't force any more of them. They seem to break at about 45 NM of torque or so...if you have to apply more force than that try other means (freezing them or impact tools) before you break another. This is precisely why I don't recommend R&R of the GPs unless they have failed...you now have made quite a job for yourself.

I would agree with the other posters. When I did mine, I used plenty of PB Blaster and a product called Freeze-Off. If your plug is free of the threads, and you still have resistance, it might just be the carbon buildup holding the tip of the plug. When I did mine, I used a deep 6 sided socket, with an extension, and it allowed me to apply outward pressure while I moved the plug slightly back and forth. I also used a torque wrench to insure that I did not apply too much force to the plug. I think Beru lists the breaking torque of their plugs at around 45 n/m. Good luck!!

Sorry to hear that the plug is broken, and I wish I had a quick and easy solution to your problem.

Although the manual seems to indicate 33 ft-lb. or so for the plug.........I've got the suspicion that they take quite a bit more than this value before they fracture.

Obviously the data is not readily available, but, I'd suspect the plug would need at least 45 ft-lb. to break it. As an example, a .375 SHCS will take 48 ft.-lb before it yields..........and the plug should be equivalent to a .375 screw or better.

While no help to the Muleears, post 17 in this thread indicates the breaking point of the Beru plug is ~85-90nm.

http://www.peachparts.com/shopforum/diesel-discussion/205418-om606-glow-plug-replacement-pray-me-please-2.html?highlight=glow+plug

I believe the MB extractor kit has extraction bits designed to grab the insde of the GP case in instances where the guts shear off at the heating element? Also, I seem to remember some other extractors being posted that looked worth a try before attempting to drill it out.

Yep, thanks Terry. I knew I recalled that from someplace.

So, figure 60 lb.-ft. as the limit..........cannot break the plug at that level.

M-B now has a tool to remove the stuck plug from the head. You might be able to find a dealer with that tool. You almost certainly don't want to buy it yourself as it is quite expensive.

this is just a thought... i have not had this happen but... what about a easy out?

You have to drill a hole to use an easy out. Don't drill into the head. And don't break that easy out off in the plug.

I know that you don't have this tool, but it might give you some ideas regarding your glow plug problem.


http://www.youtube.com/watch?v=koghDoROFko