spark plug crossthread hell

[loyalewithcheese]

hey all,

 

any tips on getting around a spark plug hole that is being a pia? i just keep trying and trying and it starts to feel good, then it stops. the threads look pretty good so unless i get overanxious i'm 95% sure all is fine, i just can't get it in the right way and it's driving me nuts!

 

tia

droo

[NorthWet]

Just something to rule out:

 

Is your sparkplug socket getting jammed up against the walls of the head casting? On my MPFI heads, this is a real issue, as one of my 2 sparkplug sockets has too thick of a wall to fit into the plug well properly (will go in, but "sticks" once torque is applied).

 

Guess which one I always seem to grab first?

 

Otherwise, I would try the socket and extension on the neighboring plug, memorize the "look" of the angles, and try your PITA plug again.

[Humble Nuto 53]

you could buy a "thread chaser" and try to clean up the threads in the head...

[N2FHL]

What's the difference between a thread chaser and a tap?

[Humble Nuto 53]

tap is designed to cut new tight perfect threads

 

chaser is designed to clean up and correct threads, much sloppier fit, and

much easier to engage correctly.

[NorthWet]

I do not know that a threadchaser has any looser fit than a tap, but they are handy to have. They can also clean out the threads of the O2 sensor bung if you ever strip out a sensor while removing.

[Marck]

Definantly use a thread chaser or tap to fix the thread. Also, put a lot of heavy axle grease oin the chaser or tap so that it will catch most of the shavings.

 

Next time you install a spark plug, be sure to stick the plug into a 5/16 piece of hose and then use the hose to thread the spark plug in until it is hand tight. This will keep from stripping out those threads.

[85Sub4WD]

I usually use anti-seize on the spark plug threads for install - makes life at least a little easier - I would also try hand tightening the plug first (if it is on the passenger side that is easy to do)

 

try that and a different socket before you think Helicoil - and even if you do have to helicoil, they aren't that hard to install if the plug is on the passenger side - I speak from expierence there (no I did not strip the plug hole out)

BTW - use a name brand one IE HELICOIL - if not it is liable to shoot the spark plug out of the cylinder - I have expierence there too

 

I actually have had the same problem with the socket hitting the casting, however I got rid of the one that had that problem. (it was a cheapie anyway)

[loyalewithcheese]

thanks for the tips, i will look for a thread chaser. i was in a kragen today and asked for something like this before i read your responses and the parts goon shrugged in stupidity. believe me, i'm not suprised.

 

i'll keep at it, i don't think there is any major damage so i think i can get it in there with some patience, and maybe some thread chaser help. this is on the left side/rear cylinder all others went on fine with the socket i have, it isn't too bulky and it does seem to be getting hung up. i'll poke around my motorcycles i think i have a tool kit plug socket that might be slimmer.

 

cheers

droo

[NorthWet]

The sparkplug tap/chaser that I have is double-ended, with one thread size for standard-size plugs and the other end for smaller plugs (like in my Ferd Aerostar); socket hex midway along its length, black oxide finish. I think that I got it at NAPA.