Can I just weld a glow plug hole shut

So i changed all the glow plugs and with the 7 of them it now fires right up instantly, however, the 8th one broke inside and went through every imaginable step trying to remove it and got everything I could see but is still a piece stuck in there and have even removed injector and still cant remove this piece and I believe I ruined the threads pretty good fighting with this piece as well. My question is that I dont have funds to replace engine at this moment but plan to do it here when finish school and at this point its just going to go sit in backyard until then unused is cant drive it how it is. So with that in mind can I just weld the glow plug hole shut and drive it with the other seven. I really don't care about this engine and if there something bad that will eventually happen I dont care just wondering if this would be ok to do for now.

Thank You

Sure, why not?

I would first try to chase the threads with the correct tap in order to screw in a short bolt or one of the old plugs with the tip cut off. As far as I remember, the glowplug threads are in cast iron and I would rather trust somewhat buggered threads than a weld that has been done without proper preheat and cooldown.

Yes you can. What cylinder is it? Is it on the drivers side? Do you have enough room to drill and tap a 1/8 NPT pipe plug and then just install a plug?

I second using a thread chaser. If someone could tell us the thread size and pitch, these chasers can be had at some hardware stores, Sears, even Amazon. They typically aren't expensive, I bought a set from Sears' online site "Shop you way" or something like that. Much prefer the thought of using a chaser to welding the head. As stated cast iron welding is a process in itself
Bulldogger

I tried exactly what was said above of trying to cut end off old glow plug and threading it in and didnt have any luck prior to writting this post but was trying to use a HF thread kit. I will go ahead and get a nicer one such as one from sears and give that a try then.

Thank You

I would think brazing would be better than welding, but as stated, all you need is a different head to bolt on. should be a few out there to get.

Bulldogger said:

I second using a thread chaser. If someone could tell us the thread size and pitch....

Click to expand...

M10 x 1.00mm

https://www.steelsoldiers.com/showthread.php?53353-Glow-plug-size

so, you are leaving the glow plug pieces in there?

Maybe liquid metal? Goes in soft. When hard, it will be in the threads to stop from falling out. I dont know temp ratings.

If you really just want to plug the hole and abandon the glow plug, and you can't get the 10mm threads to clean up, then you might look at going up a size. 7/16 fine thread tap and plug should be readily available, just need an appropriate size tap drill.

You can make a thread chaser out of a bolt: use a thin cutoff wheel to make it into a tap by cutting some longitudinal cuts at the end.


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If the tip is broken off, couldn't you just drive it and wait for the the chunk to be blown out? Just fab a sheet-metal cover to prevent it from damaging anything should it come out. Carry a good one and a tap in case it comes out so you can plug the hole than.

Reading the first post again I'm not clear on just what the situation is. With the injector removed, can you still see the tip? Do you have an opening all the way through from the threads into the injector cup, such that you can put a thin wire or nail all the way through but just can't get the glow plug in? Maybe you just need to clean the inner hole up?


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Any update?
I got a little time in the shop tonight and looked around for glowplug threadchasers I made in the past, but could not find any so I made another. Use a thin cutoff wheel to cut off the glowplug wiring connector and the glowplug beyond the threads, taper the end of the threads on a disc sander, and then cut the slots to make flutes like a tap. Orient the cutoff wheel so it makes a sharp cut on the side that will be the cutting side as you turn it in. Use a deep socket to hold it straight.

Worth a try. May not have the hardness to provide cutting / clearing of the old same stuck material. What's worst is not having a plan B then C. Anti-seize and don't over torque. It just a glow plug. Never found one finger tight or leaking under compression.