I put green tape on a few stationary objects and then eyeballed a few marks on the tape to help visualize the angle that I need to drill. Once you sheer off the glowplug it is a little harder to visualize if you dont have some markings.


here is the pic the, pen is obviously were the glow plug was

Attached Thumbnails

 

You only need to drill past the depth of the Threads on the Glow Plug so if you only go that far there is nothing to push into anything as the drilled out metal comes out.

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84 300D, 82 Volvo 244Gl Diesel

From what I have read most seem to get stuck in the threaded area due to some sort of corrosion or electrolysis.

Some have had Carbon get past the seating/sealing area and Carbon got between the Plug Body and the Cylinder Head.

A few have had the heater Element/Tip carboned so badly the Tip got stuck. I think there was 2 cases were the Glow Plug body came out but the tips stayed in the Engine.

I guess it is possible for any combination of the above to happen or eve all three of them to happen.

I five years of reading the various Forums there has been 3 people with 617s and Pencile type Glow Plugs that had issues.
On 2 the Glow Plug body came out but the Tips remained due to Carbon and one was stuck in the Cylinder head due to some unknow cause (I cant remember); of course it was the #5 Plug.

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84 300D, 82 Volvo 244Gl Diesel

Might be a good idea to heat the glow plug with a welder before you attempt removal. Induction heating might loosen the corrosion.

Glad mine is old schoo!

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85 Merc 300D - Unwinding 31 years of wear
86 VW TD
Mahindra Diesel
Iseki Diesel

In 2007 I didn't own a diesel.

One of our Members suggested using a Torch to heat the head (I meant Head of the Glow Plug; not the Cylinder Head) red hot and then let them cool.

I have not read of anyone doing this and if I remember some people though the heat might damage/melt the Aluminum Cylinder head.

Some have gone the opposite direction and Froze the GP heads in hope of shrinking them in the threaded area so the penetrating oil will get in.

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84 300D, 82 Volvo 244Gl Diesel

Heating aluminum to red hot would be bad for all concerned. Usually I have found that aluminum just melts before there is any color.

My thought would be to weld directly to glow plug base. I have done this with bolts screwed into aluminum even after the head breaks off. Just weld a 3/4" nut to it through the threaded hole in the nut. The heat from welding causes some expansion then contraction of the threads once cooled, making them easy to unscrew.

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85 Merc 300D - Unwinding 31 years of wear
86 VW TD
Mahindra Diesel
Iseki Diesel

In 2007 I didn't own a diesel.

OOPs that was supposed to mean the Head of the Glow Plug red Hot. Will change that.

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84 300D, 82 Volvo 244Gl Diesel

Hey everyone,

I'm a new owner of 1995 Mercedes-Benz E300D. And now I'm stuck with the same problem as everyone else here: broken glow plugs. The glow plugs that broke are #4 & #5, counting from the front of the car.

Which method seems to be better - drilling the plug out, or welding a nut to it, hoping that the weld won't break?

This is horrible - my car is turning into a money-pit. On the bright side, I'm hoping that once this is all said and done, I will have a smooth-running Mercedes with 207k miles on it

So I've attempted to drill out the broken glow plugs. All is going okay for now, except for the part that I don't know how to drill out the threaded portion of the glow plug without damaging the cylinder head thread. What tools did everyone use? Suggestions?

Thanks!

Can you mig weld on a good sized nut. Say 3/4"
It will give you something to turn and the heat will loosen any debris on the GP.

The trouble with me drilling one is that aluminium is a lot softer than the steel.
Good luck

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85 Merc 300D - Unwinding 31 years of wear
86 VW TD
Mahindra Diesel
Iseki Diesel

In 2007 I didn't own a diesel.

I don't have access to a welding machine + I've never welded in my entire life. It's time to start though...

I think I"m just going to use nose pliers and try to get the remaining thread out of it.

To make things worst, I wasn't able to pull the electrode out of the broken glow plug so I ended up breaking if off and now have to drill it out. Great.

Has anyone tried to remove the injectors , add wd-40 into the cylinder , then remove the glow plug .?

I would try the welded nut approach as a last resort, and cross your fingers you can weld it without melting aluminum into the affair.

Drilling out a glow plug is very difficult to do properly and the best method is clamping the head to a mill plate and using a fixed drill, not a hand drill.
Even with that (in a well lighted machine shop) there is a great possibility the drill will wander and immediately take out the threads in the aluminum - bad news. Keep in mind drilling out a stuck glow plug is probably done on a best-efforts (no guarantee) basis, ie. you pay whether or not the procedure is successful.

But if you decide to go that route, the procedure is to step drill, removing the steel body of the glow plug until it is paper thin then they chase the threads with a tap, possiblt an undersized tap. I've watched this being done - its nothing I would attempt personally.

There is however a tool I saw recently in an Internet search while looking for Beru glow plugs (why are they so difficult to find in the US?) anyhow it appears to have been made for this purpose.
I haven't used the tool and am not endorsing it, just a FYI in case someone is in a position to need to remove a stuck GP:
http://www.lasertools.co.uk/items/pdf/Products/5205_Instructions.pdf

Another remedy is having the threads removed by EDM (Electro Discharge Machining) and some well equipped machine shops will do this. I believe it should be near to 100% successful. EDM'ing is however very slow and probably costly because it has to be done by an experienced technician also the head must be setup so the EDM oil is retained vertically so the head obviously has to be off the engine for that.

This subject will certainly continue to surface on the forum because the newer style (long, thin) glow plugs are more prevalent to getting stuck.

Just be sure to use some antisieze on the threads when you install new GP's (or hope your mechanic uses some because unfortunately many don't bother with it!). That is manother discussion altogether, some like one kind of grease others like another but IMHO anything is better than nothing at all!
DDH

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!

Its VERy hard to drill straight while the head is on the car. I tried and couldnt do it. Hate to admit that I punted and took my cuurent D, a 96, to a mechanic for removal. He got them out ( using a special tool he made which allowed him to tap into the broken GP after he cut the threaded area out using index drills similar to the DIY posted here.)

With the 95, I pulled the head as it was sealing poorly anyhow.

The GP broke off at the radiius just before the threads in both cases.

When I saw that newer MBz engines have even LONGER GP's, I stopped looking at newer MBz diesels!

I didn't let the fear of newer glow plugs stop me from buying the '99 which is BTW a great performer, the last of the turbodiesels before BlueTec but THAT is definitely a good reason to stop looking at Mercedes diesels forever! .

I was looking on the Internet and discovered a firm in the UK that has a mobile service van and kits of special tools designed for extractinfg Glow Plugs! wow, that indicates there is a pretty brisk business over there, I believe the number of diesels is probably higher there too.
Extract Engineering
click on the tab describing glow plug extraction and you will see a tool installed on a cyl head with a drill running through an alignment device, pretty nice!

When attempting to remove a glow plug you should apply torque (using the right socket) evenly and if there is resistance you reverse the drive and tighten the plug and then go back to removing it. This is done alternately back and forth with copious amounts of solvent. Hoppes gun oil, liquid wrench, Kroil, there are several good lubricants that are made for this. WD40 is not among them.

If the pug doesn't work loose, squirt it well and let it soak overnight and resume the next day.
If the steel shank on the gp has formed a chemical bond to the aluminum no amount of chemical solvent is going to reach it, its just impossible and the plug is seized and will have to be broken off intentionally to drill it out.
At this point you can still drive the car, provided the plug hasn't been broken off and if you are working out of your house you may want to make an appointment with a repair shop while it can still be driven and they can either locate the proper tool to drill it out or (most likely) remove the head to send it to a machine shop. Or you can try to locate the proper tool kit (perhaps someone would make one available to rent on the Forum!?) and attempt using it.

I recently heard of a late model (96?) NA diesel W210 in great shape except it had two broken off glow plugs and the tip of one had fallen down into the cylinder so it could not be started. The fellow was working at his home and he decded to put it up for sale as-is, asking $2000. Unfortunately the car was in Las Vegas, and I didn't have a trailer with a winch and frankly I didn't need another car. I suppose this happens occasionally. Its true the newer gps are longer and thinner than ever, a disaster waiting to happen.

Anti-sieze is needed to reduce the phenomena of dissimilar metals bonding to each other with heat, over time.
It would be interesting to find out if the factory is using any anti-sieze in the initial assembly when they install glow plugs.
Maybe they do and just isn't working but finding out anything like that would have to be in German with an insider at the MB factory and those folks aren't likely to be reading this forum!
DDH

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!