Glow plug replacement

[DENNIS NOLTE]

I have a 1995 E-300..(w124).and had one glow plug replaced ...the shop said it broke off and took appx 10 hours and a big bill to replace

I now have #4 GP that needs replacing and my son & I want to replace it ourselves...but wanted to see if anyone ever had to cut out a broken GP...and have any suggestions.

Thanks
Dennis

[kerry]

Do a search on stuck or broken glow plugs. Lots of threads on the topic.

[Brian Carlton]

Originally Posted by kerry

Do a search on stuck or broken glow plugs. Lots of threads on the topic.

Exactly.

You'll find that many folks have not had the required patience and broke the plug. Then, you're looking at a risky procedure or some big money.


My best advice is to let an impact wrench do the work for you.........but, be absolutely sure the wrench is set below 45 ft-lb. It won't do much for awhile.........you may need to sit there and hammer on it for an hour........but, eventually, the vibrations must loosen the carbon and allow the plug to be removed.

Folks aren't successful in five minutes and then are likely to raise the torque and break the plug.

[Diesel911]

An ounce of prevention......

Here is a site with instructions and some pics on how to remove one:
http://alan.mcreynolds.googlepages.com/howtoremovebrokenglowplugs-mercedesom606

Ounce GPs removed ream/clean the Carbon out of the holes.
When you put in the new ones use a Never-Sieze type compound on the threads or if you are real picky and can find the stuff Beru makes grease for the Glow Plugs.

[milner351]

I just removed the glow plugs on my '95 - the rear one is a bit fun to get a socket on - you may need to get a "medium" depth 12mm socket to get the job done.

I would recommend using lots of patience and penetrating oil.

Work the plugs back and forth as you are removing them - CCW about a 1/2 turn, then work it cw / ccw / cw / ccw, then try to get another 1/2 turn ccw - especially if it feels hard to turn - STOP - soak with penetrant and move to the next one.

I've gotten all but one of mine out - the last one is totally unthreaded - but is still stuck in the carbon inside the head - I've been soaking it with penetrant for a while - and trying to come up with tools to allow me to pull / pry it out completely.

[JimmyL]

Good grief this sounds ominous!! I am currently purchasing an OM606.910 with at least one inop glow plug. [no light until afterglow]
What type and size of socket removes the intake manifold? [need to go ahead and get stuff together]
What exactly breaks on these glowplugs? The tip breaks off inside the head, it snaps at the threads? What??? With all the back and forth stuff it sounds like maybe the tip is the issue?
Diesel911, do you have any of these glow plug reamers available? I've loaned out the OM616/617 reamer twice that I got from you, but have yet to use it. I now need one for an OM606......

[curlytom]

No biggie, I have the mechanical skills of a 14 year old girl and I changed mine with hardly any problems by following this advice X 10 - I also used a torque wrench set at 50 lbs;

Originally Posted by milner351

...I would recommend using lots of patience and penetrating oil.

Work the plugs back and forth as you are removing them - CCW about a 1/2 turn, then work it cw / ccw / cw / ccw, then try to get another 1/2 turn ccw - especially if it feels hard to turn - STOP - soak with penetrant and move to the next one.

[Diesel911]

Originally Posted by JimmyL

Good grief this sounds ominous!! I am currently purchasing an OM606.910 with at least one inop glow plug. [no light until afterglow]
What type and size of socket removes the intake manifold? [need to go ahead and get stuff together]
What exactly breaks on these glowplugs? The tip breaks off inside the head, it snaps at the threads? What??? With all the back and forth stuff it sounds like maybe the tip is the issue?
Diesel911, do you have any of these glow plug reamers available? I've loaned out the OM616/617 reamer twice that I got from you, but have yet to use it. I now need one for an OM606......

Will send PM shortly.

If it was me and the weather was not too bad I would pull all the plugs as soon as I could.
I know some people think it is asking for trouble to pull a still working plug but I think the longer the plugs are in the Engine with no Never-Seeze on them and Carbon building up around them the bigger the problem will be later.
And, it is better to deal with a problem when you can plan time for it.

[TMAllison]

Serach threads by Kartek and Notfarnow for sucess stories removing broken GP's using McReynolds process.

I'd set the torque wrench no higher than 40-50NM rather than 50 ft lbs. The breaking point in a vise is ~90NM.

I'm a proponenet of replacing only the one that is bad. Why create a problem removing something that works?

[JimmyL]

So what exactly is the failure point, and the breaking point????

[Brian Carlton]

Originally Posted by JimmyL

So what exactly is the failure point, and the breaking point????

IIRC, the failure point is what Terry mentioned............about 65 lb.-ft.

I'd feel safe using a wrench limited to 45 lb.-ft. Anything less might not accomplish much.

[JimmyL]

I'm doing horribly at asking my question.
What part of the glow plug breaks??? Tip? At threads?
Dilithium Crystal? Warp plasma coil?

[muleears]

Mine broke below the threads. Mine came out with difficulty, then when the threads were clear of the head, it finally snapped off just about flush. Mine is a turbo and some say they are worse. I hope none break off for you

[spark3542]

Originally Posted by JimmyL

I'm doing horribly at asking my question.
What part of the glow plug breaks??? Tip? At threads?
Dilithium Crystal? Warp plasma coil?

The GP breaks right below the hex flats. Therefore the hex portions spins free, and the center core is still connected at both ends. When this happens, it entails breaking the connector end to remove the hex portion, then using fairly standard broken-bolt-removal techniques. It's not pretty.

I found great success on subsequent glow plugs by: warm engine, lots of PB Blaster, torque wrench set to 50NM.

[Diesel911]

Originally Posted by JimmyL

I'm doing horribly at asking my question.
What part of the glow plug breaks??? Tip? At threads?
Dilithium Crystal? Warp plasma coil?

The Hex head snaps off and it can be due to it being seized in the threaded area or the electrode of the GP being trapped in by Carbon or a combination of both at the same time.

I guess that it is also possible for the Plug body to come out and leave the Carbon trapped electrode in the Head.