Broken Glow Plug Question

[papakb]

The electrical system does provide the power to the glow plugs but it is not a constant current type system. Each individual glow plug acts as a resistance load on the batteries and draws current based on it's internal resistance. The good plugs are low resistance loads and will draw the most power. As they begin to fail and their resistance rises they begin to draw less and less power until the burn out and effectively become open circuits. Leaving them energized too long is what causes the problems.

Hopefully you had a vacuum cleaner in the injector hole to suck out any drill chips when you did that. It's not a good idea to have them floating around in the cylinders. If any did get into the cylinders most of will probably just blow out when the engine starts anyway but you don't want to get one stuck on a valve seat or between the piston and the cylinder walls.

 

[patracy]

Alright, so just wanted to say I love this forum and everyone on here is amazing and the advice is incredibly helpful! So I said the **** with it don't plan on keeping this motor for all that long I'm going to go for it on drilling it out and if cant get it will just go with metal can route. I took a small bit as advised and placed a couple sofa pillows down on the wheel and the part next to wheel and a few towels over the side right there and got comfortable for the long haul and begin drilling away with a small drill. So after a long time drilling and was making some headway which was really difficult with the center part sticking out still I noticed it start to spin. Well, low and behold the threads must have got heated up from all the drilling and it came right out. So now I got the threads all the hole however the remaining glow plug including the remaining threads are still stuck. At least I can go to bed tonight on a positive note knowing I have managed to save this terrible scenario and get the threads out.

However, since its still stuck is my best bet at this point to just grab on the threads and break the threaded part off and try and get the pieces out from inside the injector?

In case I confused anyone above I had broken the injector with the threads in the hole and now after a lot of drilling the threads spun out the hole so now the hole is no longer blocked by the threads however now i just have the swollen plug still in there along with the bit of threads that got out the hole still hanging on the end of plug.

You have hit the lotto when it comes to that backing out. Trying to break the remaining section off and pulling the remains out the injector hole likely will be the course of action. Just be careful that you don't damage the threads in the hole. Some people have been lucky enough to pull the power lead off the IP and spinning over the motor and the plug pops out. But I don't like the thoughts of it. (It could break and drop down the injector cup hole into the cyl. Which is BAD)

 

[tage]

I believe missing one glow plug will cause the others to overvolt, producing a cascade of failed glow plugs.

Do without functioning glow plugs entirely - keep your truck in a heated garage....

Please reference your opinion... In the tm...

I have ran my hmmwv on 4 glow plugs for a very long time... I think you're confusing the over volt by a burnt up coolant sensor. Or when the box goes bad and supplies voltage constantly.

 

[98G]

Please reference your opinion... In the tm...

I have ran my hmmwv on 4 glow plugs for a very long time... I think you're confusing the over volt by a burnt up coolant sensor. Or when the box goes bad and supplies voltage constantly.

I'm wrong. I readily admit it.

I went digging to find where and how this little nugget of misinformation found it's way into my consciousness. It came from here -

https://www.steelsoldiers.com/showthread.php?136867-Glow-Plug-Failure/page2

it seems the cascading failure of one glow plug after another is an artifact of the resistor used on the CUCV's 12/24v system and not applicable to the hmmwv.

Now I know better. Thanks everyone for your assistance in the flushing of this little nugget of false knowledge.

Back to the OP - thanks for the update. Keep us informed how it progresses.

 

[tage]

no problem bro. Just some OCD.


Weld a nut to the end of the glow plug. that should get it unthreaded from the head, and even have enough to leverage to pry out the swollen tip. I have used the cheap labor freight flux core wire welder, and expensive diesel ran arc welders. very doable for a first timer.

I was always taught to drill as a last resort.
so as a last resort....
since you don't care about this engine, you can use an easy out into the plug to finish unthreading the GP from the head, and break off the end of the GP back into the cylinder and let it get "processed" by the engine. but if you get it unthreaded you can prolly use a GP tool.

 

[cclary25]

Well, I tried to put a nut on it and pop it out but no luck so finally just drilled out some more from the center of it and it finally crumbled in on itself and was able to pull most of the pieces out however the glow plug round center part is still in it so tonight going to go ahead and try to fish it out from the injector hole.

I do have one question though, I am paranoid I may have bumped the threads while drilling out the broken piece. Should I get a 3/8 threading tool and run it through just to make sure threads are all good before trying to put the new glow plug in?

Also, were do you buy the tool to reach in the injector and pull piece out i believe its a medical tool hemostat or something like that? Would harbor freight have this?

Thank You

 

[ken]

Yes Harbor Freight will have it. They also have a small magnet on a stick that you can fish around in there to get smaller pieces that you may not know or can see in there. If you can find the right size tap to clean the threads go for it. Or get a round wire brush for your drill and spin it in the hole to remove any carbon build up. Also get some never sieze for the threads on the new glow plug. To prevent the from happening to you again.

 

[ken]

Oh yea I almost forgot you mentioned 3/8 threads. They are actually metric threads. They are 10mmX 1.0 pitch. You would also need a bottoming tap for this.