Partially damaged spark plug hole on 115 optimax

[dan the gman]

What is the best method of repairing the threads on a spark plug hole on my 6 cylinder Optimax? It’s the upper cylinder on the right bank. The first few threads are looking damaged and the plug won’t start to thread. The angle is kind of challenging and I’m concerned about having enough room to work. Thanks for any suggestions.

 

[Yegboats]

Heli coil

 

[Alumarine]

Something like this might solve the problem.
You'd have to get one with the right threads.

20020 Limited Access Spark Plug Chaser

Fits Spark Plug Holes with Limited Access.

www.lislecorp.com

 

[ONERCBOATER!]

Helicoil...had to do it to 1st outboard I ever owned....line 35 yrs ago.... some one that looked an awful lot like me may have been ham fisted as a teen and might have overtightened a sparkplug on a 1957 johny and completely stripped the threads....then started it and was surprised when i heard a loud pop and the plug escaped the block.

I was not popular that weekend, a friend's mechanic helicoiled it and saved my bacon.

I don't recommend the overtightening part but I do strongly recommend helicoils and casesavers.

Sean

 

[stresspoint]

Something like this might solve the problem.
You'd have to get one with the right threads.

20020 Limited Access Spark Plug Chaser

Fits Spark Plug Holes with Limited Access.

www.lislecorp.com

this . remove bits off the motor till you can get a good strait line to the plug hole ,
run the chaser with some grease to catch cuttings.

no short cuts , do it right or you will do more damage.

 

[QBhoy]

Above advice is the way to go…
On a side note…is she definitely a 115 and a v6 ? Not sure I’ve been aware of such an engine…but I’ve been corrected plenty of times on here before !

 

[airshot]

If only the first few threads are damaged, another option is to remove the head and run the tap/ thread chaser from the inside out. This will keep all the threads in alignment while correcting the damage. When you come in from the outside, you MUST have the thread chaser in perfect alignment or you will have a mismatch. All depends on how bad those first few threads are actually...

 

[vroom ZOOM]

maybe look around on ebay for a good used head?