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Glow plug tip break off while driving

Will L.

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I know that several people had problems with the electrical tabs coming off where the wires connect. So no engine damage, just part failures. Those were On this forum and on the Hummer Network forum.

One person was removing his glowplugs to do a compression check, due to misfire and was missing the electrode. He never tore into it and sold his truck. He gave my cell number to the new owner and he pulled that head off to find same thing you have. He ripped out the 6.5 and dropped in a cummins.

I pulled my engine apart having what I thought was an injector tick. I was planning new coated bearings, head and main studs, headwork, etc with around 70k miles on my optimizer. Found the same thing you have. New set of coated 18:1 for me now from Twisted Steel.

There is another I suspect but that engine will just go junkyard according to the owner when it does give out.


Bosch won’t honor them even with proof of where you bought them. Send them back and get AC Delco 60G.

Sad because Bosch German made injectors are long proven best. Then The India ones were goofy, but now they seem to be on point. Seems bosch has to go from good to garbage, then later correct it. But since they won’t even bother looking at them... I’m done with them. I wasn’t even trying to get them to pay for damages, just wanted them to look into it so they aren’t wrecking everybody’s engines. They simply don’t care. Every 6.5 in the world could blow up and they are too big to care.

I did a thread on here about my piston somewhere. I just cant find it right now.
 

wirenut450

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Just out of curiosity what side of the engine where the glow plugs on yours and if you know the others? Mine was passenger side #3 . I had thought maybe I had damaged it installing it, my thought was using a long extension there is the possibility to accidentally manipulate the extension and maybe apply side pressure while inserting the glow plug as some I have noticed are fairly tight tolerance probably from buildup of carbon. The other thing I have read is a dripping injector could cause the electrode tip to swell or be completely destroyed. On the packaging for the 60g where does it say they are manufactured? The Bosch says made in France. I still plan to order some right away, I definitely don't want to have another one let go like that.
 

Will L.

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I don’t know about the others.

Mine was in my Hummer, no tool issue there. I put a socket on the plug and use my fingers on the socket until the end. Then attach the ratchet to tighten. Hummer is more accessible, no extension needed. I can’t remember which cylinder is was at the moment.

No turbo on the side on hummers
 

MrMarty51

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Use a 10mm spark plug hole thread chaser and clean carbon from threads before installing new GPz. I know this does not pertain to broken off electrodes, it does however pertain to getting new GPz installed and set to proper torque to prevent them from breaking on installation or removal.
Be sure that the device is a thread chaser and not a thread tap. A tap will remove thread material and weaken the hole. a chaser will clean and realign what is already there.
 

wirenut450

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Yes, I am aware of that as well as dripping injectors can cause the glow plugs to swell or burn off. This is an actual documented failure of the glow plug electrode tube mechanically separating from the threaded body of the plug and falling thru the precup opening into the cylinder and being smashed by the Piston as there is only 45 thou clearance when the Piston is at TDC...
 

wirenut450

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Definitely will not be running the Bosch plugs anytime soon... I pulled all the plugs and cranked over the engine till I had oil pressure built up before starting the other day and found one other glow plug tip that had a missing electrode. So I now believe I actually had 2 separate events the second more catastrophic than the first one, 1 plug dropped the electrode on the way down to Portland and the other on the way back. Learned lesson here, never stop learning I guess no matter how much of this stuff you do. One thing lead to another to figure this out but once I found the damaged valve tip and then pulled that head finding the Piston with the electrode imbedded in it I figured that was it. I should have pulled all of them made the wrong assumption that everything happened in that one cylinder figuring it maybe had Imbedded in the Piston too and then came loose again accounting for the 2 separate occasions wrong assumption on my part and poor follow thru. Either way no more Bosch glow plugs for me . The truck fired right up sounds great. I have some reservations about should I or shouldn't I pull the other head and inspect the other cylinder?
 

wirenut450

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I will at the least send my bore scope up thru the oil drain plug to the bottom of that piston driver side rear #7 and double check that there isn't an obvious crack. Will.L the ones that you had and know of that dropped glow plug electrodes, did they also have cracked pistons ?
 

Will L.

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Mine didn’t crack he piston, but it chewed up the top of the piston. No other damage anywhere.

When I spoke to Bosch and was trying to tell them there is an issue they need to fix- the only way they would look at it is if I filled a warranty claim. Their requirements are- has to be bought within last 12 months from an authorized seller. If purchased before then or anywhere not an authorized seller, they won’t even look at it.. Rock auto is the only online authorized seller according to them. Then there are some of the regular auto parts stores that can sell them. Depending where and how long ago you bought them- may be able to file warranty claim if you have a receipt. Not sure what they will do to repay you, but might be worth chasing.
 

wirenut450

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"This may or maynot apply to you but the tips burning off is a sign of over advanced timing"...

I do plan to confirm my timing as I don't want to overlook something again... This was a pain in the arse and would not wish it on anyone. Thanks for the recommendation.
 

Will L.

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My understanding is the over advancing timing burns it shorter and shorter. That would not cause a tip to break off and have enough material to destroy a piston. It would just wear away.

And i can guarantee mine wasn’t advanced when it happened. I verified my timing when I put in the plug set that failed.
 

wirenut450

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That is my understanding as well, I have checked mine a number of times as well and am confident that it is correct also. Just figured leave no stone unturned, you can find lots of documented burned off plugs from advanced timing I couldn't find barely anything on the whole tip breaking off like that.
 
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