cleaning spark plug threads...

After I spun a front wheel stud and then chasing the studs and nuts on the other nineteen (don't want an expensive suprize at state inspection), after 105k figured cleaning up the spark plug holes wasn't a bad idea.

Ran a search, no answers, can I use a regular tap or do they make a less aggresive one just to remove the crud in the threads, less risk in screwin' things up I'm supposing.

Thanks, and good nite...

Check with engine houses - like Summit, Jeg's, or Goodson - for "thread chasers."

They're used for cleaning up threaded holes, using the existing threads as a guide. The thread chaser "forms" the thread, rather than cutting it, which helps to keep you from crossing the threads.

A set of thread chasers is something every serious mechanic should have in his toolkit - right next to the taps and dies.

Thread chasers are available in sets for nearly all standard sizes - but get the plug thread chaser (M14x1.25, IIRC) on it's own, since most of the 4.0 threads are "inch."

5-90

Local parts store should stock "thread chasers".

If you have a good tap and die set, you shouldn't need thread chasers.

Now what's the problem with your spark plug holes, did you strip one? Keep in mind little metal shavings that you make with cleaning those thread will fall into the cylinder. So if you don't need to do it, don't.

Nah, didn't strip anything, but have had the platinums in there for I don't know how long. Always antiseized 'em, so I think there has to be a lot of residue all over the threads.

I should correct my wording in my original post, I used a tap and die to "chase" the wheel studs and those factory closed ended lug nuts, up to this thread was only vaguely aware there might have been specific thread "chasers" out there.

Maybe I should just blowgun around the plugs prior to removal, vacuum the wells before and after, and maybe run an acetoned rag (or maybe not, crap falling into the head?!?) wrapped around a dowel or screwdriver around the threads and use some copper-based anti-seize I just bought for another task. I sense that the muscle I put into those wheel studs/lugs using the die/tap does not belong in a plug hole.

Or to be safe, nix the rag idea but do everything else. Sometimes my "improvement" ideas go awry:laugh3: .

Thanks all so far...

To clean spark plug threads use a chaser, and coat it in grease to catch any of the shavings. There really shouldn't be alot of shavings though. If it takes alot of force you are doing something wrong.

The dowel and rag will work fine. Bit of thinner and work backwards so stuff come out and is not pushed in or keep a shop vac nozzle right there running to suck up any loose stuff that comes free.

Use a HIGH QUALITY tool....I have seen what a cheapo "thread chaser" will do to the threads....if the plugs screw easily in and out, you don't need to chase the threads anyway.

I don't understand why you want to "clean" the threads? What's the problem with it right now?

If the plugs thread in without problems it's good.

I don't know about you guys but when I put plugs in those puppies go in by HAND, actually FINGERS with at most a spark plug socket and if there is ANY binding it goes no futher. Learned my lesson having owned aluminum heads on some big bucks motors that cost me some bigger bucks...

For the love of dog, man dont fix it if its not broken. If i tried to do that I'd end up with a helicoil.

RichP said:

I don't know about you guys but when I put plugs in those puppies go in by HAND, actually FINGERS with at most a spark plug socket and if there is ANY binding it goes no futher.

Click to expand...

I use an old spark plug wire to seat and start the plugs. Then I use the extension+universal socket without the ratchet, feeling with my hand, then finally with the ratchet as the last step.

Yes, I am paranoid about cross threading so I take my sweat time and do it in 3 quick steps.

_Maz

Well, seeing that I can't remember when I last changed the plugs, I think I'll carefully back them out, maybe wire wheel the threads on the old ones and use them with some oil or light grease to clean things up, then use acetone and a dowel, then the copper-based anti-seize.

And maybe even my torque wrench!!!

A bike store mechanic/friend uses the copper stuff because of the fine threads and the nature of the bottom bracket to become immersed in crud and freeze solid. And I really want to avoid any kind of chaser, cmotsvt, you remind me of me :gag: .

Thanks all, appreciate all the angles...