If I was in the same situation as you, I would feel fine with plugging the hole and driving it. If the tip of the glow plug was stuck bad enough to break in the head, I doubt it will not seal out the coolant. As far as the plug, I would use a pipe plug and Teflon tape.

Maybe slather some jbweld in there first in case the coolant slowly washes out the carbon then one day *boom* catastrophic failure.

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You need to ascertain where you have drilled into first. It is not possible for us to tell from looking at photos. Have you pulled the injector to see if you drilled through the glow plug and through the pre chamber? Is there coolant in the pre chamber? If you have not breached the pre chamber, that may make plugging that cylinder more feasible. It will lower the compression of that cylinder though since you will no longer have a glow plug tip extending into the pre chamber, which will lower the compression ratio thus the compression. Not sure what that will do to the engine.... more smoke, more vibration, lower mpg?

I have not pulled the injector yet. Will this just be a visual inspection? i.e looking for coolant or breakage below the injector? If the tip of the GP is still intact, will I see it? It is my understanding if I try to pull the prechamber out as well, that insures breakage of the tip. Sorry, I just don't know what I am expected to see down there.

Also, no one has commented yet on if that circle next to the drill bit IS the Glow Plug. The reason I keep harping on that is because if it is, it looks pretty intact to me.

If you look at the nice cutaway head diagram Maxbumpo posted, you can see that after pulling the injector, you should be able to see the glow plug tip as well as the ball pin. A normal pre chamber should be dry, covered in a light coating of carbon. DO NOT attempt to pull the pre chamber since the glow plug is still in there, you will cause more damage.

It is hard to tell by photos. You need to have a glow plug in your hand and probe what you have drilled to determine how far you have drilled.

I agree. I think I see an inner circle (glow element) and outer circle (body).

Idea: Remove the fuel thermostat, see what kind of access you have to the INSIDE of the cooling passage. Long shot, but maybe there will be a way to get to the backside of the hole?

The issue you'll need to solve is keeping the remains of the glow plug from moving backward into the cavity. Maybe pack with JBWeld before you put in the plug?

Thanks for sticking with me guys. Bare with me. I work an hour and a half from where I live. So I chat with you guys during the day and then look under the hood when I get home, access what we discuss, and then report back the next day. Please stay subscribed to this thread and I will update when I can.

Will try and get some more details tonight. But it's the weekends that I really have time to roll up the sleeves.

Since you've already breached a gallery, I say cap it up. this engine will start fine with 5 maybe 4 glowplugs.

You'll prob need to put resistors on the electrical lines to prevent codes and lights in the cabin.


If I was certain of where I was drilling and had a good feeling about getting directly into the tip of the Gp, then I would go for it. It will be harder to seal up thou if you do.

I am with Rollguy. tap it. and bolt it up.

although I should also say, I am happy to pay a machinist when I can admit a blunder.

I'd likely pull the head if I had 2 messed up plugs. But thats just me, it can work without them.

Winter might be tough on you.

Plugging the entire mess off would probably be the easiest plan.

Removing all of the remnants, and reinstalling a new glow plug would be the best remedy (if it can be done).

Are the threads for the GP still intact? If so, a new glowplug could be coated in release agent, and oushed into the hole with the breached area packed full of JB Weld or equivalent (probably a high end industrial epoxy made by the likes of loctite).

With a little luck, you'd have the same profile as the original hole, with just a small part of the bore being epoxy. You may be able to even have a welder tig that coolant passage closed before this epoxy reconstruction.

Packing with jb weld before plugging has my vote too. It could not hurt, the head is too far gone to be brought back 100 percent.

That's what I'm talkin'' about!

Jim Smith would be proud here!

actually, the 604, and 605 are identical to the 606... in valve and Glow plug layout... just fewer cylinders...

601to 603 use two valves per cylinder, and a short glow plug.