Stripped spark plug hole and Insert won't stay in.

[fishonboat]

I took my outboard (1970 Johnson 25hp) out on Thrusday evening for a trial run and this is the first time out with a new head gasket and a thread insert to replace one of the striped spark plug holes. After returning home and giving the motor time to cool I started to remove the spark plugs to check for any signs of water to make sure I had a good seal with my new head gasket and when I removed the Spark plug the Thread insert came out with it. Also I noticed that the outside chrome portion (wear you put the wrench on the plug to unscrew it) of the Spark plug was much duller then the other plug after the trial run. I have started the motor in the drive way on the garden hose and pulled the plugs and had no problems with the insert then but this is the first time driving it hard after the insert was installed. This is the type that uses a substance similar to Locktight. Any thoughts as to how I can keep this thing in. Also the insert was still stuck to the plug. So what I have done is applied more of the substance that the insert kit came with and I screwed the plug back in the hole with the insert still attached. I gave it a couple of days to Dry and I was able to unscrew the plug and the insert stay in. I will try it again but I have a feeling it's just going to come out again. If this doesn’t work what are your thoughts on applying some JB weld around the threads on the insert and screw it back in.? Thanks for the help.

 

[Chinewalker]

Re: Stripped spark plug hole and Insert won't stay in.

If it were mine, I'd probably keep an eye out for a new cylinder head. A head off an 18 or 20 of the same era will NOT work, so you need one off a 25.<br /><br />The only problem I have with using an epoxy or the like is heat will likely kill it in a hurry, plus it will affect heat dispersion. Try it and see if it works - if not, get another head...<br /><br />- Scott

 

[CATransplant]

Re: Stripped spark plug hole and Insert won't stay in.

Replace the head. That'll be the only real fix for this. If you need one, contact an outboard junkyard like tcoutboard.com. They'll have dozens of them available.<br /><br />A replacement head will restore your 25 to reliable service. Anything else will fail.

 

[sly36]

Re: Stripped spark plug hole and Insert won't stay in.

i know they have tread insert you dont need locktight in this tread insert they have 4 pin when the tread insert is sceew you push that 4 pin in they stuck inside.<br />The cie here in canada made that is "spaenaur"<br />they call E-Z thread inserts<br /><br />good luck!

 

[sly36]

Re: Stripped spark plug hole and Insert won't stay in.

http://mdmetric.com/pdf/keysert.pdf

 

[rennen]

Re: Stripped spark plug hole and Insert won't stay in.

Just get a new head. You will be able to clean the pistons and head in the process. I bought a used head for an evinrude 40 for 25 bucks... the gasket is almost 25bucks.

 

[Chris1956]

Re: Stripped spark plug hole and Insert won't stay in.

Fishon, I had the same problem with a spark plug insert on an old motorcycle head. I would try cleaning the head threads and insert with carb spray and then mix up some Marine-tex and smear it on the insert and install it with the plug. After it hardens, it may just hold the insert in. it worked for me!

 

[fishonboat]

Re: Stripped spark plug hole and Insert won't stay in.

I would perfer to find another head but that may be tricky given the age of the motor. I did send twin city outboard an e-mail to see what they have. They are closed today so I couldnt get through to them. If I can't find one I may try that insert with the 4 pins. That does look kind of nice. So no one thanks that the JB weld will work? Thanks for the help

 

[CATransplant]

Re: Stripped spark plug hole and Insert won't stay in.

Nah...your motor's a youngster. Twin City Outboard considers that a newish outboard, and they'll have scads of heads. Not to worry.