Pardon my ignorance, but I've never needed to use a thread chaser until now.

I picked up this tool today, to attempt to repair some spark plug threads. The chaser didn't come with any instructions. And I figure there's gotta be some experts on here.

How far into the spark plug hole is this little number intended to go -- how many rotations? I got about 4 full rotations in, and the resistance gets quite high. Am I supposed to push beyond this, and thread this thing all the way in?

 

Should go into the seat. Make sure you have some lubricant on the threads to catch whatever comes loose. It will also make threading in easier.

 

Make sure the valves are closed. They are at times in line with the spark plug hole. You can look down in with a light to make sure or use a bore scope. Should not be very hard to turn, you're only cleaning the threads not cutting new ones.

 

I've not heard of anyone chasing plug threads----what suggests this as an action while changing plugs?

 

Did you make sure the valves were both closed and the piston was away from the top?

 

I should clarify. I'm not asking (or proposing) about chasing threads as part of a routine plug change procedure. I had a plug eject (detailed in another thread) and I was attempting to possibly fix myself - at least fix enough to enable me to drive it to the shop with a plug in the empty hole.

The piston was down and valves closed. But...that shouldn't matter much - should it? When installing the Timesert, I totally see how having piston down and valves closed is critical. But for chasing threads, isn't there adequate clearance?

 

Probably has enough clearance if the chaser is not ran too deep.

 

If you're able to go in four threads- then back it out and clean off any metal shavings and start over.
Go in 4.5 turns then back out a half. Then add 1 turn, then back out 1/2. then go in 1, then back out 1/2.
Slow and easy progress.
How far to go overall: I don't know.