need HELP! with stripping sparkplug!

[deadaheadub]

So I'm taking the #3 plug out for the first time on my '76 2.0L fi, and it comes out snugly the whole way out, unlike the others. I get it out and now it won't go in straight, and it crossthreaded the hole the first few threads down. So I didn't go any further down but took it out before going very far. I'm thinking if I can get the first few threads cleaned there should be plenty of threads left to hold it in fine. But I can't get the tap to thread as straight as I'd like and am afraid I'm going to strip it more. Help! Anyone with experience or knowledge on this PLEASE give me your advice. What can I do to have the tap go in very straight, with no angle, into the hole, so that it lines up perfectly with the threads further down? I'm feeling pretty desperate, and I don't have any experience with this. I don't want to irreversibly damage it! Thank you!

[RSorak 71Westy]

Most likely it was cross threaded before, and now there's 2 sets of threads.
Just concentrate on trying to get the plug to start straight in to the right set of threads. Do not worry about cleaning and or repairing anything at this point.

You should be able to get the plug to go in the right set and screw all the way down and then it'll be fine.....

[bottomend]

This is a "touchy" job ( get the pun?) You need to feel the new threads biteing. YOu also need to use some oil. Even WD40 will work in a pinch. Honestly though, I wouldn't do this without taking the engine out of the car and the head off the engine. this is the type of problem that can be fixed but it can also be made much worse if you mess it up. Sorry...

[Amskeptic]

I'm thinking if I can get the first few threads cleaned there should be plenty of threads left to hold it in fine.

The problem here is that your correction must perfectly segue into the existant threads. This is severely unlikely. You will most-likely have a tough trip down to the seat. The question then is going to be, will the plug hold under combustion pressures? And any screwing around that you are doing right now is raining aluminum slivers into the combustion chambers where they will compromise the cylinder wall/ring surfaces.

Even though pulling a head off may seem like horrible major surgery, it is not all that bad and you can get timeserted and put together correctly (clean oil cooler fins nicely assembled tins and other detail work) now and forget about it.
Colin

[deadaheadub]

Thanks. I came to pretty much the same conclusion and have resigned myself on my first engine drop and head removal. It's daunting for me, never having done it, but it'll be great all that I'll learn doing it. And hopefully it'll make me more confident to take her up to the Arctic Circle in June. I'll get to do all sorts of things to it to make it more sound to go that distance. I just hope I can get it back up and running in time for the trip, not knowing what kinds of stumbling blocks may arise getting it back together.

[Amskeptic]

Thanks. I came to pretty much the same conclusion and have resigned myself on my first engine drop and head removal. It's daunting for me, never having done it, but it'll be great all that I'll learn doing it. And hopefully it'll make me more confident to take her up to the Arctic Circle in June. I'll get to do all sorts of things to it to make it more sound to go that distance. I just hope I can get it back up and running in time for the trip, not knowing what kinds of stumbling blocks may arise getting it back together.

The Type 4 engines are very forgiving of partial surgery, got the teeshirt.
Your only over-arching rule here is to keep lifter bores and cylinders clean as you r&r the heads. Please use penetrating oil on all exhaust fasteners at least 24 hopurs before you disassemble.

I do not who is going to repair the plug hole, but if your intuition says don't trust them, don't. I have had TWO instances of machinists who sent me the wrong vibe and I over-ruled my stomach's desire to turn and flee. Both times they screwed up my engine parts royally.

Time-wise, you should be good. Two days to get head off, a couple of days at the machinist, and three or four to reassemble nice and neat with some painting of engine tins as necessary (I give the full 24 hour cure before handling any painted parts).
Colin

[deadaheadub]

The Type 4 engines are very forgiving of partial surgery, got the teeshirt.
Your only over-arching rule here is to keep lifter bores and cylinders clean as you r&r the heads. Please use penetrating oil on all exhaust fasteners at least 24 hopurs before you disassemble.

I do not who is going to repair the plug hole, but if your intuition says don't trust them, don't. I have had TWO instances of machinists who sent me the wrong vibe and I over-ruled my stomach's desire to turn and flee. Both times they screwed up my engine parts royally.

Time-wise, you should be good. Two days to get head off, a couple of days at the machinist, and three or four to reassemble nice and neat with some painting of engine tins as necessary (I give the full 24 hour cure before handling any painted parts).
Colin

Thanks for the tips. I welcome any and all good advice.
I was hoping to clean the threads by screwing the threader in the sparkplug hole from the inside of the head out after I get it apart, cleaning up what I think are the only few bad threads at the top and hopefully will have good usable threads without any other surgery necessary. If not, should I attempt to put in a timesert myself, have a shop do it, or go some other route? What other option would I have at a machinist?
Thanks
Ryan

[vdubyah73]

The Type 4 engines are very forgiving of partial surgery, got the teeshirt.
Your only over-arching rule here is to keep lifter bores and cylinders clean as you r&r the heads. Please use penetrating oil on all exhaust fasteners at least 24 hopurs before you disassemble.

I do not who is going to repair the plug hole, but if your intuition says don't trust them, don't. I have had TWO instances of machinists who sent me the wrong vibe and I over-ruled my stomach's desire to turn and flee. Both times they screwed up my engine parts royally.

Time-wise, you should be good. Two days to get head off, a couple of days at the machinist, and three or four to reassemble nice and neat with some painting of engine tins as necessary (I give the full 24 hour cure before handling any painted parts).
Colin

Thanks for the tips. I welcome any and all good advice.
I was hoping to clean the threads by screwing the threader in the sparkplug hole from the inside of the head out after I get it apart, cleaning up what I think are the only few bad threads at the top and hopefully will have good usable threads without any other surgery necessary. If not, should I attempt to put in a timesert myself, have a shop do it, or go some other route? What other option would I have at a machinist?
Thanks
Ryan

That's a good idea. If doing a timesert scares you, look in the yellow pages for automobile machining. An old school auto parts store may be able to do it out back, find one that caters to mechanics.

Bill

[bottomend]

Threading a new hole is all about "feel".

I admit it; I finally got my stripped out hole fixed six months ago and I took it to my guy. i had been driving around for at least a year knowing that I had buggered a couple of the threads.

I watched him do it and it was a subtle process. I wouldn't feel weird about doing it myself now but I had 36 hours to get the engine OUT and back IN the car so I couldn't afford to be messing around. If you can save the exsisting threads... do it. It'll be better than a timesert ect.

If you've never done engine work then you need to be aware of how clean stuff needs to be. You HAVE to be able to eat off the surfaces when reasembleing componants. No discussion... And no Huskies laying around nearby when you're working. Too much hair!

[deadaheadub]

Thanks. All great stuff for me to hear and know, not having done it before.

[DjEep]

I was hoping to clean the threads by screwing the threader in the sparkplug hole from the inside of the head out after I get it apart, cleaning up what I think are the only few bad threads at the top and hopefully will have good usable threads without any other surgery necessary. If not, should I attempt to put in a timesert myself, have a shop do it, or go some other route? What other option would I have at a machinist?
Thanks
Ryan

I did this with my experiment-engine. It had a crossthreaded plug when I got it, on a brand new head. It was only a few threads in, so I took an longer old plug from the westy (it takes 3/4" plugs, the spare engine takes 1/2") and used it as a tap from chamber out.

[vdubyah73]

I saw a tool in a NAPA yesterday. Forget exactly what it was called, but it's made for exactly this problem. I'll call it a reverse thread chaser. You insert it through the plug hole with the head installed, then it expands, much the same as an exacto knife clamps the blade only the opposite. Then you just back it out. It came in various sizes. It wasn't cheap, but maybe you can rent one.

Bill

[deadaheadub]

That does sound perfect, exactly what would do the trick. I'll have to find a NAPA; we don't have any anywhere close. If not, I'll check the other FLAPS. Thanks