Need advice: Stripped glow plug threads - Alfa Romeo Forum
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(Post Link) post #1 of 5 Old 28-09-16 Thread Starter
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Need advice: Stripped glow plug threads

I was supposed to do a quick glow plug service on my 159 1.9 8v, but that plan soon came to an end when some of the threads on the second glow plug came out with the plug itself. (2nd plug counting from the cam belt). I replaced the plug with bad threads with a new one, but as I started to tighten it the threads snapped. The plug is still mounted, and the car runs just fine, but I have to get this sorted.

After talking to the best Alfa garage in the area I have some alternatives, but I need help to figure out what to do.

Alt 1. Take the head off, drill out threads and replace with Helicoil. A very expensive job. About £1000
Alt 2. Buy a used head and replace. Still very expensive, but maybe a bit cheaper than alt. 1.
Alt 3. Use a slightly larger tap to enlarge the glow plug hole, and replace the glow plug with a larger one. What plug should I use then?
Alt 4. Use a tap to refresh the threads and get hold of some strong Loctite that will keep the plug glued in place. This will maybe be the easiest and cheapest fix, but will it hold?

How do I deal with this? What would you do?
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Ouch... not what you want to encounter when you're doing a regular service.

However, as I've been in the same boat once, there might be a solution that is quite an easy fix compared to the alternative of taking the entire head off.

In my case it was concerning an overtightened small type of spark plug from a 156 1.8 Twin Spark. What I successfully managed to do by putting in an insert and drove it another 250k KM since.

Just take a look at Timesert company based in Vegas. They offered a great and very, very fast service when I ordered directly instead of via Würth (which re-sells under their label). Give them a call and keep your cc ready (price is well worth the savings you will have compared to a head-off job).

Good luck!
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I might be inclined to pop down your local motor factors and see what alternative plugs are available with a slightly larger dimension. Re tap the thread but swarf entering the head isn't desirable. Will need to be careful.
Failing that there are some good apoxy products on the market of the putty variety which might do the job, even a high temp silicone (again don't get it in the head).

I used apoxy putty to repair a cracked motorcycle crank case years ago, it's still going!

What a pain
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(Post Link) post #4 of 5 Old 30-09-16 Thread Starter
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I like the Time Sert inserts, they look really nice. But it's a very tight spot, so is it possible to rethread the glow plug hole (cylinder 2) without removing the intake manifold? Are there any instructions on how to disassemble the intake manifold? The fuel rail has to come off I guess.

Maybe I should contact an Opel shop, the engine is the same as theirs. Someone must have done this before. Stripping glow plug threads aren't that unusual.
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Try option 4 first. If it works, great. If it doesn't work you are no worse off than you are now and can try one of the other options.
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