Thread: Stripped plug hole - what now?

Originally Posted by rick130

Which is what we were all taught to do when drilling or tapping into something critical that's still assembled, but I've never been comfortable with it.

greasing the tap works fine.. done a few in my time.

i always do them in three bites and clear the grease and swath each time.

Originally Posted by incisor

greasing the tap works fine.. done a few in my time.

i always do them in three bites and clear the grease and swath each time.

will vouch for that,Unca Dave did one for me on Fraser a year and a half ago and still running good (now where did that lump of timber get to?)

Heli coil works!
I had a stripped thread in the spark plug hole of a head of the XJ6.
Start the motor and the plug travelled six feet into the air

Fitted a "Heli Coil" and have had no problems since.
It sure is a problem with alloy heads, sumps, etc.

Cheers,
Ron

Heard an interesting method many moons ago, but never needed to use it.

Crank the engine around by hand so that the exhaust valve on the cylinder you want to tap is slightly open.

Adapt a compressed air hose to the exhaust and apply enough pressure to get a decent flow out of the plug hole .

Tap away.


I worry that you might blow rust or soot back into the cylinder. Maybe you could achieve the same effect with a bit more mucking about through the inlet manifold

A friend of mine engaged the services of a professional to helicoil the plug in his ford flathead V8 (all cast iron). The man connected a vacuum cleaner on blow to the exhaust pipe. As mentioned before, if you were doing it to your own engine, you would take the extra time and effort, and connect it to the inlet manifold. Turning the tap back frequently would also keep the size of the swarf pieces small.
Aaron.