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130 Crossthreaded Plug

S

ss396fish

Contributing Member
After having my FORMER mechanic put on a set of timing belts and finding he had it out of time, I was looking for TDC and found that when he replaced the cracked head about 3 years ago he had apparently crossthreaded the no.1 plug. When backing it out it would tighten up after only about 1/2 turn. Gonna leave it be as long as the fish are biting but trying to find out how to best deal with it. I guess if I'm lucky it will come out and leave enough threads to chase with a tap but I'm not counting on it. Can a helicoil be done? Can anything be done without removing the head? Damn him.....
 
I had a seized no. 3 plug in my 225 which ruined the thread when it eventually came out.
I had a timesert fitted (better than a helicoil) by my local car garage for £40 without removing the head.
Some shavings went into the cylinder when the new thread was cut but I managed to suck them out with a shop vac and anything I missed must have just been blown out the exhaust.

Get the engine properly hot before you take the old plug out, you may get lucky.
 
Sometimes a bit of carbon can build up on the end of the spark plug threads and cause it to jam coming out. You can run the engine, then loosen the plug and spray with PB Blaster or some Sea Foam and let it soak a couple of hours or more. It may come out no problem.

If you find the plug hole is badly damaged, TimeSert thread repair is the way to go and is superior to Heli-Coil as metal-chicken said.

Good luck.
 
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And use an anti seize when installing plugs in anything. New vehicles with high mileage platinum plugs etc. are very susceptible to seizing in the hole, especially with aluminum heads.
 
I don't the differance between a 130 and a 225 but the plugs in mine are way down in a hole. Will that be a problem?
metal-chicken said:
I had a seized no. 3 plug in my 225 which ruined the thread when it eventually came out.
I had a timesert fitted (better than a helicoil) by my local car garage for £40 without removing the head.
Some shavings went into the cylinder when the new thread was cut but I managed to suck them out with a shop vac and anything I missed must have just been blown out the exhaust.

Get the engine properly hot before you take the old plug out, you may get lucky.
Click to expand...
 
Shouldn't be, the plugs on the 225 are down a 6" tube. Speak to some local garages - they may be cheaper and have more experience of fitting timeserts than your marine mechanic.
 
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