Spark plug socket stripped

[Rich Snopkowski]

Re: 10 HP Johnson Mod. QD21S
In preparing to winterize this motor, and in removing and replacing one of the plugs, I apparently cross threaded and stripped the socket threads in the cylinder head. Pretty careless and maybe stupid of me.
Is there any way to repair this other than replacing the cylinder head?

 

[Barnacle_Bill]

Re: Spark plug socket stripped

Search the marine store here for heli coils. Your local auto parts store would also carry them.

 

[Tim Frank]

Re: Spark plug socket stripped

One of the best things on this forum is the breadth of knowledge stored on previous posts, and how easy it is to find.
The search engine is pretty efficient.
That said, here is a relevent thread :

http://forums.iboats.com/showthread.php?t=237231&highlight=repair+spark+plug+thread

Good luck.

 

[1970kayhydro]

Re: Spark plug socket stripped

i had the same thing happen to me on my 71 40hp johnson. i had napa put in helicoil, didn't work. eather they messed it up or just not the way to fix that. i ended up taking to head to the welding shop and had the hole filled and redrilled all together and napa took care of the bill, not sure how much it was i think about 40$. i still have two holes in the motor cover from the plug shooting out of the head, so don't stand behind the motor.

 

[Rich Snopkowski]

Re: Spark plug socket stripped

Thank you for the advice. I looked at the new heli coil kits for sale on line. They seem to be pretty expensive, about $139. I probably can buy a used head much cheaper than that, if one can be found. Someone mentioned that NAPA auto did the job for them, but apparently not very well. What was the cost? I might try that anyway first.

 

[samo_ott]

Re: Spark plug socket stripped

$139 for a heli coil kit is ridiculous. And I have seen folks install them themselves and not very well. I'd go to a local metal shop or call around. I would think you can get that done for under $50. In addition, the QD heads are plentiful, look into a used one also.

 

[Rich Snopkowski]

Re: Spark plug socket stripped

Thanks to all for the help and advice. This is obviously a fairly common problem. Does anyone know the proper size heli coil or other insert? The spark plug is a J6C.

 

[joho5]

Re: Spark plug socket stripped

mine did the same thing and I contacted a local machinist and he just suggested to fill it in by welding, or welding a plug all the way around, then retapping the screw hole.

he was going to charge $50.

 

[samo_ott]

Re: Spark plug socket stripped

Thanks to all for the help and advice. This is obviously a fairly common problem. Does anyone know the proper size heli coil or other insert? The spark plug is a J6C.

They're all pretty much the same size for spark plugs. Let the metal guys worry about diameter and thread count!

 

[1970kayhydro]

Re: Spark plug socket stripped

I don't remember what Napa charged it wasn't but maybe 40$ but the only thing that worked in the end was the welding shop. I think they did both holes for the same 40$ then its like new!

 

[tmasloske]

Re: Spark plug socket stripped

I just purchased a 1968 Evinrude 18HP and the previous owner had stripped out the lower spark plug threads. I had checked into the Heli Coil kit at my NAPA and it was $47 and I had to pull the cylinder head. I checked with Twin City Outboards and they shipped a used head for $59 to my front door. If you go this route, they'll want the casting number stamped into your old head.

 

[demitche]

Re: Spark plug socket stripped

I have the same problem with 70hp Johnson and I see by the replys that there is not much faith in the helicoil repairs, has anyone had any success with helicoils?
Thanks
Don

 

[Lone Duck]

Re: Spark plug socket stripped

i had the same thing happen to me on my 71 40hp johnson. i had napa put in helicoil, didn't work. eather they messed it up or just not the way to fix that. i ended up taking to head to the welding shop and had the hole filled and redrilled all together and napa took care of the bill, not sure how much it was i think about 40$. i still have two holes in the motor cover from the plug shooting out of the head, so don't stand behind the motor.

Yup! many years ago when I was an apprentice , my teacher was killed by putting a heli coil in a chainsaw. Plug went in his throat just under the jaw. maybe they make them better these days but you won't catch me using a heli coil. Not ever!!

 

[kenmyfam]

Re: Spark plug socket stripped

Helicoil properly installed is as strong as the original. You have to make sure there is enough material there for the thread depth required by the helicoil to begin with. If not then that is how an accident can happen.

 

[1970kayhydro]

Re: Spark plug socket stripped

Im not tring to give the answer but i won't use a helicoil again...