Broken Glow Plug

[BlueLghtning]

Looking for you opinions and knowledge on what our options and risks are here.

Sarah and I had dropped our Beetle off at one of the recommended TDI mechanics to have the completed timing belt & water pump done along with a few other things, one of which included checking the CEL light. I knew the code was for glow plugs, but wasn't sure what was bad, if it was the harness or plugs or both.

All the work was done as promised, but when I called over to confirm it was complete and get the final tally he informed me that 3 of the 4 glow plugs needed to be replaced, but when trying to remove one of them, it broke. He said he had never seen it break as low as it did. I was already headed that way to pick up the car and I'm not sure why I didn't question him more about why he didn't try to extract it (or did he) or get more info on what he had tried. He said we could come back at another time and try to work on it and help us out. I think in hindsight, I should have told him to keep the car and fix it and make it right, but I went ahead and picked it up. I was just thinking we only had 1 glow plug working and it was starting fine, now we had 3 working ones, we should be good. The weather has been getting much warmer here and I wasn't really worried about the car not starting. We'll just get the broken part out later.

Anyway, we got there and he went over what he had done and had all my old parts to show me, including the glow plugs. At the first quick glance, he explained that it looked like there was a thread or two holding in the broken plug. He said when it first happened, he was worried about the remaining bottom part falling in the engine, but then he decided the hole is tapered towards the bottom and enough of the larger part exists that it can't fall all the way in to the engine?

I was pretty easy going about it when he told me, but we would want it fixed. I did tell him that extracting a broken glow plug was way above what I was comfortable with though and I'd need his help getting it out and fixed correctly.

So tonight we had a friend over that's a machinist by trade and started getting his opinion about the broken plug and if he had any ideas and thoughts on it. He started comparing a good plug and the broken one and pointed out there are no threads left. What is broken off is past the thread cut off point. He started mentioning the possibility of it just getting blown out of the hole its self, but that brought up the question will the car stall if that happens or stop running? Obviously it probably wouldn't be a good idea to keep driving it if that happens either. My wife was planning on driving a couple hours to Chattanooga this weekend and now this has her concerned to the point she wants to rent a car vs taking the beetle. We just paid to have the timing belt done among many other things for the piece of mind and now we have another possible issue on our hands.

So my questions are as follows, plus the pics below of the broken plug next to a good one.

1. Is there a possibility of this broken plug falling into the engine causing catastrophic damage?
2. Can it blow out on its own and what are we left with if that happens? (my wife is capable of putting in an old glow plug if it blows out, but doing it on the side of the highway in the dark is not very high on her list).
3. How much of a risk are we at of continuing to drive the car like it is?
4. Am I out of line thinking this mechanic should be fixing this issue? He tried to remove it and he broke it? I don't think I should be the one risking making things worse by trying to extract it myself. There's obviously a possibility if things go totally bad, that the head would have to come off to fix it and that sure isn't good.

I'm not here to bash this mechanic at this point. I will give him a fair opportunity to correct this and give him praise for good work when he does. For all the work he did do and provide us with, his pricing was very fair, and his work was good and thorough. He spent a lot of time going over what he would be doing and made us feel very comfortable. I know stuff like this happens and maybe my very laid back presence when I picked the car gave the impression that it was no big deal, which I really didn't think it was at first. However, I also didn't think there was much risk when I picked it up, but I do want it fixed correctly for sure and now I'm getting nervous that there may be some risk leaving it right now.

Here are the pics. Click on any pic for full size resolution.

The circled part is what is still in the engine. As best I can tell it is broken off below the thread line?

[Lew]

Try this site and see if any of the Glow Plug topics will help you......Good Luk!
TDIClub Forums - Search Results

[BlueLghtning]

Originally Posted by Lew

Try this site and see if any of the Glow Plug topics will help you......Good Luk!
TDIClub Forums - Search Results

Yeah, I was trying to search that site last night, but it was down for maintenance.

[BlueLghtning]

Okay, this post by Wingnut along with the hand drawn diagrams makes me feel a little bit better about the plug not falling in the hole. However, reading that most plugs seem to fail with at least the majority of the threads still attached, I'm really curious how this one is staying in? I'm not feeling so good about it not just blowing out on my wife while she's driving.

Originally Posted by Wingnut

OK. Well first of all. I am sorry to hear it was not an easy fix. But I am glad you took it to a qualified mechanic.

There is an option you should consider before taking the head off. You (or your mechanic) can drill & tap the hole and put a heli coil in it without having to remove the head. Here is the kicker, you need to be able to do this without loosing any part of the plug into the head. If you make sure the piston on that cylinder is at TDC, then that should prevent the plug end from falling into the cylinder if it breaks loose from the body.

Here is a crude drawing of the glow plug hole:



Now, if you drill down to the red line, that should remove all the threaded part of the glow plug:



Once you drill out all the threads, there will be nothing holding the plug in there. But don't remove it just yet. Use it as a plug to prevent the shavings from the tap from going into the head.



Once you get enough room in there, you can easily tap new threads for a heli coil. Once the new threads are tapped, clean out the hole with compressed air & then try to remove the rest of the plug. It should come out easily at this point since there are no threads holding it in there. Its basically just sitting on the tappered part of the head.

Remember, it has been in there plugging the hole, so there shouldn't be anything in the cylinder at this point. Just make sure you clean it well. Once the remains of the plug are extracted, simply insert the heli coil in the threads you tapped & you should be able to throw in a new plug. It might not be a bad idea to use thread lock to hold the heli coil. Let it set up before inserting the new plug though. You don't want to thread lock the plug in there.

I think this may work. It will be time consuming & trickey, but a lot less involved than removing the head, which is about an 8-10 hour job. Plus, the parts do do a head removal are expensive as you might as well do a complete timing belt job while you have the front of the engine apart.

If anyone thinks this is a bad idea, please let me know. But IMO, it can't hurt to try. The worst case scenario is that something goes wrong & you have to remove the head anyway, but at least you tried.

[lightflyer1]

From what you show it shouldn't fall in. If somehow something did fall in it will create catastrophic damage if the engine is running or turned over, so be careful anyway.

I would think there is some chance it could blow out on its own and have some force behind it as well, so don't be around when/if it does. You probably shouldn't be running the engine or driving the car until fixed. If you are and it comes out, it will probably run really bad on 3 cylinders.

The mechanic (any mechanic) should/could fix the issue. Make sure they know what they are doing and are comfortable with the procedure. Take it back to the same mechanic if he is up to it and you feel comfortable with them. These things happen and no necessarily the fault of the mechanic here, but he should have fixed this before giving the car back. This would be at your expense though. As an analogy if the mechanic is working on your car and breaks a screw/stud off, you are charged for removal and replacement. I have broken things when I worked on my own car just due to the fact of corrosion and such. Stuff happens. If the current mechanic isn't comfortable doing this work get recommendations or check the "guru" list over at Fred's TDI Page. TDIClub.com. VW TDI Enthusiast Community when it comes back up and find someone good who can do this. I would think it can be done without removing the head. Good luck with it and post back to let us know how it comes out.

[Lew]

I replaced my ceramic plugs with steel plugs a while back.....All the plugs came out without a problem.....they were tight for sure.....a 10mm quarter inch drive deep well socket with a couple of extension attached is what I use....before going back in with the new steel GP's I applied a little never seize. it's a good thing!

[BlueLghtning]

Just an update, I spent some time last night talking to the mechanic that worked on the car (who is one of the recommended TDI guru mechanics from TDI.club).

He really doesn't think there is much risk for remaining part of the plug to come out since it did manage to break below the threads, its obviously attached in there pretty good. The more I talked to him, the more I get the impression he doesn't feel its even going to come out without removing the head. I also didn't realize the entire long inner electrode piece is still all in place. The way ours broke definitely seems unique. I haven't found any pics of others that broke like ours did.

So I guess this will be a project to be on the back burner maybe before winter gets here again next year.

[Lew]

I failed to mention in my earlier post. I did spray a little Blaster around the old ceramics GP's and let soak
overnight before removing.