cross threaded spark plug hole

[kreepa]

i just got an 89 240sx fastback, and went to put in new spark plugs and found that the previous owner cross threaded the hole. i managed to get it out, but i can only get the new one bout half way in. what do i do?

[NISTECH]

thread chaser

[kreepa]

thread chaser

? whats that?

[DAEDALUS]

A tap. Get a tap the same diameter and pitch as the plug, and run it through. The 2 risks are that 1) It might not leave enough thread to hold torque, and 2) It's almost guaranteed you'll drop metal shavings into the combustion chamber (which are aluminum, so you can't pick them out with a magnet).

Here's one: http://www.gearheadtools.com/16503.htm

Make sure the piston is near bottom dead center.

[DAEDALUS]

delete double post

[kreepa]

thats what i thought, but 2 questions, why bottom dead center and where do you think i could get that at the store? like does sears or autozone sell individual taps, i usually only see sets

[DAEDALUS]

A "spark plug thread chaser" is a very common item. Any Autozone or Pep Boys should have one. Bottom dead center just to guarantee the tool doesn't hit the top of the piston, in case the tap is long and the head thin. Shouldn't happen, but some precautions are easy enough. If you can, rig a thin hose to a vacuum cleaner and suck out the chamber when you're done to try and get any shavings out.

[kreepa]

awesome, thanks!

[Z3Px]

hey did you ever get the thread chaser?i just ran into the same problem, a spark plug will only go in half way, and i got a thread chaser from autozone. is there any tips you can offer while doing this, besides being really really carefull:D

[IvoryJ30t]

actually, coat the tap with alot of thick grease. that way it might grab most of the aluminum shavings instead of dropping them in the cylinder.

[Z3Px]

WHEEWW!!! That was a pretty scary event there. It was indeed cross threaded, but with a little might and alot of grease, we were able to get it in there and back out. I think there is a major flaw in those thread chassers, is that they are to danged big, its really hard to get those things stuck in there enough to where you can actually work with them. But anyway, i think it started to get crossed threaded during the fule injector event (search "fuel inkjectors" and find my post). we had to take them in and out like 3 or 4 times. anyway, thanks for the info.