cross threaded spark plug on '80 SC

[snowtire]

It was quite difficult to get the tool engaged--you have to twist the knob while holding the tool still. Doing this in the close confines of the engine compartment is not easy. I was juuuust able to do it one-handed, but then figured out how to get two arms in there. I then gingerly tried to back the tap into the threads. It wasn't easy--I kept referring to the mirror to make sure the tool was centered in the spark plug well. Finally, I got about a full turn on it but then ran into too much resistance to continue by hand. I stewed about the decision of whether to put the ratchet on it and apply more force. Finally after checking and rechecking that it was centered, I did it. It resisted a bit, but not so much as to cause me to worry. I backed it out slowly and---voila. The tap was covered with aluminum chips:

[snowtire]

I started the spark plug back in the hole without any further cleaning or messing around. I figured that I could cause more trouble than I would fix by blowing compressed air, etc. I put a very light amount of torque on the plug, wimping out when I got it just barely tight. Probably like 5 or 10 ft-lbs. I bolted everything all back together, checked the other plugs, put the hoses back on, and....

And then I got in and turned it. It fired right up, no loud noises. It sounded awesome, nice and raspy just like it should. Even though it was stone cold, I revved it quickly, blipping it a few times to 5000 RPM or so. My thought was that this would help blow crud out of the cylinder if I had inadvertently dropped stuff in there. I am really happy about this. I will be adjusting valves this weekend or next weekend, so I will have another chance to check torque on the plug.

I want to thank all of you for your suggestions, help, and moral support. I will keep the list apprised of further developments.

[47silver]

thanks for the post, that is a great tool to have.

[ruf-porsche]

Better to take your time at inserting the spark plugs correctly then to go out and buy a tools to fix up your FUCHS UP.

[Thomas Owen]

Nice writeup. Posts like these make this board invaluable.
Good luck -

[spiff]

Wow! I feel honoured to have made a suggestion that Grady is going to use and that helped. I forgot about the clearance issue as my friend that used this tool did it on an old cavalier with lots of straight above clearance. He has no mechanical ability, but was able to make it work so I thought it wouldn't be too bad.

Great write up with photos and I'm glad there was enough clearance for you to use it. Hope I never have to do this, but I also hope others will take advantage. Maybe this is a product that Wayne should stock? Again no affiliation, but seems to save a ton of work....

[snowtire]

I agree this would be a great part to stock. Is there a way to suggest this to Wayne?

I don't think I mentioned, in defense of the Fuchs Up comment, that this was done by the previous owner. I think this was a shade-tree mechanic tune up deal, and he cross-threaded the plug. A good pre-purchase inspection with compression test would have caught it (shame on me for not having one done). Given the ominous possibilities, a potential buyer might be able to chisel a few thousand out of the sales price because of something like this...

[Superman]

Yes, this is a good story and a responsible approach. Of course, if the plug was really being stubborn, I would also have been afraid to force it. Probably.

But I will say these things: I have, twice now, had my engine spit the #6 plug out. At least one other Pelicanhead has reported the same thing. Perhaps it just hadn't gotten torqued properly. I strongly suggest you monitor that plug.

My #6 plug threads in the head are fine. I rebuilt my engine recently, and have a clear recollection of inspecting those threads. So, you do not need buggered-up threads to spit a spark plug out. don't assume that.

And finally, while I, obviously, accept the premise that the spark plug threads on a 911 engine can be cross-threaded, I have to believe it is not easy to do. The recess is long and narrow. So much so that it is difficult enough to get the plug and tool down in there. The additional challenge of getting it way down in there, and then get it cocked sideways enough to cross-thread.......can't be easy.

[CharlesJones]

I think the problem is that they go in at a slight angle, not straight perpendicular to engine. I find I have to refer to a spare head I have to remind myself of the angle to aim for.

[azasadny]

I always seem to have a problem with plug #1, not #6. anyone else have problems getting the plug installed correctly on plug #1?

[DW SD]

Originally posted by azasadny
I always seem to have a problem with plug #1, not #6. anyone else have problems getting the plug installed correctly on plug #1?

Art,

I'm not sure if this answers your question.

Always start the plug by hand. You can use a length of thick (and relatively stiff) fuel line. I would recommend maybe 8" to 10" hose that snugly fits around the outboard end of the spark plug. That makes a nice flexible extension, which allows you to turn by hand, but also ensures you don't cross thread the head.

Along the same lines, I use a nice snapon spark plug socket that has a built in universal joint and an extension with a locking mechanism (so when I pull the tool out the socket doesn't separate from the extension).

I never use a ratchet to start until I've spun the plug in the threads as far as it can go by hand - which is usually 6 to 8 threads deep. Torque gingerly with a torque wrench to factory specs. Tightening too tight can ruin threads, too.

I alway use anti-size compound applied just on the threads of the spark plug, too. Not liberally, just lightly.

Doug

[azasadny]

Doug,
Thanks for the useful tips!!