blacky

Thoughts on using thread chaser on heads when replacing spark plugs?

alexrckid

I would have to think that unless you suspect some sort of a thread problemcross thread, I hope not), then why..?? and, you'd have to be real careful not to drop and thread castings into the cylinder..............I've always used some anti-seize on the plug threads on all of my cars...maybe this, along with proper torque, have helped to avoid problems...

working on it

On iron heads, I use a chaser every time, to clean any rust or debris from the threads. On aluminum heads, I never use one. If the plug came out with no aluminum on the threads, then the steel threads of the replacement plug will do their own clean-up. If there are aluminum fragments on the pulled plug's threads, then I'd use a light and mirror (or borescope) to evaluate the damage (if/not significant). If minor, just use the new plug to do the work. That way, you would have the plug installed even if you felt a burr in the process. For major thread damage, a chaser wouldn't help. A threadsert might be needed to replace the damaged threads. I've replaced threads on the engine before, in the early 70's, but only on a VW Beetle, with side mounted heads that I vacuumed the drill debris from (I don't know if I'd try it on a Ecotec 4-valve engine though).

Radco

As other have said only if needed! But if you do use one coat the tap with grease to grab as many flakes as you can,, Make a turn remove wipe off, go alittle farther, remove wipe off till you do the whole thread hole,, do not twist hard , go slow, and always put a tiny bit of anti seize on the spark plug thread,, If cross threaded and you need a heli coil I would have a pro do it!

blacky

Very valuable and clear advice.

This is something I'll apply in all similar situations, and pass on to others.

Steel thread chasers in aluminum heads are generally not a good idea.

Thanks

Grizzly old man

I'm not exactly Android expert at using a helicoil bet I have used them many times and have never screwed one up, yet anyway.
I rarely ever use a thread chaser unless there is a problem when I remove the plep

IgottaWoody

Thread chasers are for damaged threads...and where critical torque is required,where any debris will change the readings.... anything else is just wearing out the threads unnecessarily and inviting h hardware to loosen up.