1966 Johnson VX-12 60HP

[glasspar]

Last weekend with my boat at full throttle, the motor suddenly turned off. When the top was popped, the #1 spark plug was loose and somewhat stripped around the threads.<br /><br />I was unable to get the plug back in, and the motor would no longer start. <br /><br />Does anyone have any ideas what may have caused the plug to go loose, and how the stripped threads on the motor can be repaired or replaced?<br /><br />Thanks in advance!

 

[OBJ]

Re: 1966 Johnson VX-12 60HP

Hello glasspar and welcome aboard!<br /><br />Striped threads are usually caused by either overtightening or getting the plug started in crooked. Spark plugs only need tightened to 12lb torque.<br /><br />The hole can be repaird with a helix coil. The kit can be obtained from any NAPA or good auto center. The kit will have a tap, helix coils and a set punch.<br /><br />It's best to remove the head when using the tap to prevent any chips from getting inside the cylinder. It will help you also to keep the tap straight. Using helix coils is common practice and they work when installed correctly.<br /><br />Don't hesitate to post any other questions you may have.....thanks.

 

[rickdb1boat]

Re: 1966 Johnson VX-12 60HP

Sometimes it just happens. It may not have been tightened completly during the last install or the threads may have been bad in the first place. It can be fixed easily by a Machine shop using a helicoil insert. I had this happen on my older Johnson years ago and they had it fixed in a 1/2 hour. I took it to a auto parts house that had a machine shop in the back.<br /><br />EDIT: yeah, what OBJ said, except I took it in for repair with the head pulled off...