Glow plug broke in cylinder head below the threads on AHU TDI

The glowplug snapped. I can see all the threads in the hole(which are stripped). That bugger is down in there deep. Im scared to drill into it and try to extract it. I don't want to spend money on new head. I don't have the patience to remove the head and get a machinst to attempt to fix it. Basically im just flat broke right now.

Anyways, my best mate had a look at it. He said no way will that glow plug fall into the hole. He removed another glowplug and seen how the hole looked. It's shaped like a funnel, so it's basically impossible for the whole piece to fall down in there. Well cool. 3 glowplugs will be alright for now until I can afford a new head.

But, he said maybe the center heating element will fall down in there. Looking into this hole I can see the broken glowplug and the center ceramic(?) element. Can anyone tell me about this piece? Is it solidly fused together or should I be worried about that ceramic element falling into the engine?

I know this isn't a basic TDI question, sorry.

Anyways, I fixed it for now. Maybe. I filled the hole with JB weld and inserted a bolt in there. Letting it cure as we speak. I know it's a ghetto fix, but I think it's fail safe. If the engine doesn't explode first, I'll replace the head in the spring.

Don't replace, contact Frank06 here. He can fix it for far less than a new head. If you have some miles, he can also do a great valve job.

Keith_J said:

Don't replace, contact Frank06 here. He can fix it for far less than a new head. If you have some miles, he can also do a great valve job.

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Remember that one glowplug hole is now full of JB Weld. I see that being a problem, but maybe not. I'll ask him.

well--would have been nice if you wouldnt have done that----ive got a glwplg stuck in another retired b4 i have----i ran veg oil in it--had nothing to do with the gp breaking---but--i tried to blow it out with compression--no go----i was going to get a old injector--and make a adaptor to thread into the inject hole, with a air hose fitting on the top--air pressure that cyl, then try and drill out the center of the broken gp--with a small long carbide bit. was going to get one just smaller than the od of the bottom of the gp.........and was hoping that when i got it drilled, that the release of pressure on the barrel of the gp, would blow that small part out of the hole--retired the car before i got to that-----------but before i pull the car apart--im going to try it--so if someone else runs into this-----------------------------

Careful. If it is cold, that cylinder will not fire and you will just load it up.

Don't sweat it, I had 2 break off on me last year about this time. You will not need to replace your cylinder head. I ended up having to take the head off and take it to a machine shop. The machine shop brazed nuts onto the top of the busted plugs. They did an excellent job. Since you can drive your car still, go to a place where they can so some brazing for you and you should be able to get them out. The lesson I learned about this is always change them when your engine is hot, replace them once a year and apply anti-seize when you install the new ones. Here is a picture of my busted brazed GPs.



You can give something like this a try to repair the stripped threads.

Im worried about that cylinder loading up, yes. I was sure I didn't need a new head. Mech told me I did, but I wouldn't believe it.

I would go to a machine shop and have them do it. Problem is that the glowplug hole is now full of JB Weld. Surely I have to take the head off and that hole will need to be drilled out with a drill press. That bolt I inserted, plus the JB weld in there. Its not coming out without engine surgury.

I really do hope it's fine until the spring. I'll be prepared to remove the head then.

There is little to be gained from removing the head as everything has to be done from the top anyway. I needed to take mine off or have my car transported to the machine shop because one of the stuck GPs came out just enough to allow combustion gases to escape around it. Given the choice again I would probably have the car transported. Hopefully you didn't damage anything with the JB.

I could have used this photo before now. Oh well. My glow plug is broken off somewhere below the threads. It would need to be pulled out, not threaded out. Compressed air and the engine running normally wasn't enough to push it out. Im starting to think that what I did today was completely stupid and pointless. I think i'd have to remove the head as to prevent any metal from falling into the engine. I could see that the threads are damaged. Badly. Don't know how they could even become so damaged.

Diesel Fumes said:

I think i'd have to remove the head as to prevent any metal from falling into the engine.

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Nope, a $30 compression tester from Harbor freight has a piece that screws into the injector hole, it has female pipe thread on the back end so you can run compressed air into the cylinder (with both valves closed) and then when you drill nothing can fall into the cylinder as there will be 100 PSI coming out as soon as a hole is made, I'd wear safety glasses for that operation

Jack, the kit I have from HF doesn't have an adapter for the injector hole, just the glow plug hole.

whitedog said:

Jack, the kit I have from HF doesn't have an adapter for the injector hole, just the glow plug hole.

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D'oh! I was thinking IDI

It wouldn't be too hard to rig something up to get air pressure in the injector hole though.

jackbombay said:

D'oh! I was thinking IDI

It wouldn't be too hard to rig something up to get air pressure in the injector hole though.

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Rubber stopper with a hole in it of the right size to fit the injector hole. Adapter to an air supply to plug into the hole, a forked plate with a hole in it. The injector hold down bolt holds the plate down, the plate holds the stopper down. 100 PSI is way more than needed. 30 PSI would suffice.

That's just the first thing that came to my head that had half a chance of passing the sniff test.

I don't doubt the compressed air method would work. But I drove 2.5 hrs on the highway before I did anything to it. Honestly, I was expecting a shotgun sound and a hole in my hood. But it didn't happen.

The compressed air would just keep any drilling waste/chips from falling into the cylinder.

I'm not asking for what could be embarrasing details, but did this thing break off due to some type of accident, or was some sort of meaintenance being performed?

whitedog said:

I'm not asking for what could be embarrasing details, but did this thing break off due to some type of accident, or was some sort of meaintenance being performed?

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Mechanic was removing the glowplugs to check them(CEL was/is on). He said the broken one was probably broke for quite some time. No antiseize on threads. They must have been put on tight by previous owner. I dont know though. I didn't witness the whole thing.

Beru website has instructions on how to remoe glow plugs without breaking them off.

http://www.beru.com/download/produkte/TI04_e.pdf

Someone here mentioned that you should change the glowplugs when the engine is hot. I thought you were always supposed to do it on a cold engine?

Yes... I've been following this closely over the past several years... The consensus is... that there's no consensus... Some very highly regarded experts have come down on either side of the issue...

YMMV

Yuri.

fossill said:

Beru website has instructions on how to remoe glow plugs without breaking them off.

http://www.beru.com/download/produkte/TI04_e.pdf

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Excellent post. They show the proper GP removal procedure as well as answering most GP questions.

Great document. Beru's "how-to" for a seized glow plug makes sense. If you were starting with a cold engine and heating slightly by running it a few minutes the metals in the gp and head would expand at different rates maybe giving just enough clearance for a penetrant to get down in the threads. Interesting that they say "no lubricants" installing the new gp's. I always put a dab of never seize on spark plugs but when I think about it that may contribute to overtorque which may be the reason things get seized in the first place.

RT1 said:

Great document. Beru's "how-to" for a seized glow plug makes sense. If you were starting with a cold engine and heating slightly by running it a few minutes the metals in the gp and head would expand at different rates maybe giving just enough clearance for a penetrant to get down in the threads. Interesting that they say "no lubricants" installing the new gp's. I always put a dab of never seize on spark plugs but when I think about it that may contribute to overtorque which may be the reason things get seized in the first place.

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I don't see the point of antiseize if A. you torque them correctly and B. you change them often.

But if you're going to have those plugs in there for 3-4 years or whatever, you better use antiseize. Doesn't take much. And you should use highheat stuff I think. Not that brown stuff/

I have some with aluminum and graphite in it. I figured that would be best since it's an aluminum head. Copper is quite a ways away from aluminum and iron on the galvanic chart and it's closer than lead. Any thoughts on that?

whitedog said:

I have some with aluminum and graphite in it. I figured that would be best since it's an aluminum head. Copper is quite a ways away from aluminum and iron on the galvanic chart and it's closer than lead. Any thoughts on that?

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You don't want to mix copper and aluminum, it will undergo galvanic corrosion.

Naimanator said:

You don't want to mix copper and aluminum, it will undergo galvanic corrosion.

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Right. That's what I'm saying. What about the lead vs aluminum? obviously aluminum is the same, but what about lead (or maybe it's zinc?)

whitedog said:

Right. That's what I'm saying. What about the lead vs aluminum? obviously aluminum is the same, but what about lead (or maybe it's zinc?)

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Most are zinc, fine for aluminum because the Zn is more reactive than Al. It will eventually vaporize on very hot items like exhaust systems. This is why the nickel based stuff is recommended. Nuclear grade isn't required, that is just a very low cobalt type of nickel since Co captures neutrons and gets quite hot as Co60.

No lead in most anti-seize compounds. RoHS aside, it just isn't good.

Copper-based is better for stainless and titanium fittings. Also good high temp applications.

Diesel Fumes - I see you migrated over here from airriders.ca. Why oh why did you fill it with JB weld? What I woulda done is to put a small dab on the end of a small bolt, then have it stick to the end of the GP, and when it cured, try to break it loose and pull it out. Or break it loose and crank over the engine to pop it out.

If it starts in the winter on just 3 glow plugs and it isn't leaking compression I'd let it ride til the spring if you say you're going to pull the head then. Who knows, maybe all that hot/cold cycling might loosen the broken part up some. It is ghetto, but that jb weld shouldn't be much to get out of the hole.

Using a T-handle instead of a ratchet might have prevented this.

Why? Say a bolt needs 100 foot-pounds of torque to break it free. And you have a 1 foot long wrench. It would take 100 pounds of force on that lever to break it.

So that force places a 100 pound force on the bolt in shear as well as 100 foot-pounds of torque!

Using a T-wrench with equal force on each leg will eliminate this shear force.

Using a much longer moment arm, say 10 feet, will reduce this shear force by a factor of 10. But not many have one that long. Or need one. Using the T-wrench eliminates shear.

On regular bolts, we don't care because there is enough metal in the bolt. But on GPs, they are HOLLOW. And not as strong as regular bolts.