[noeettica]

Naah if 'ya Strip threads clamp motor to a bench plug hole down set piston at BDC and feed compressed air into exhaust as helicoil tap cuts shavungs are blown from sp hole ... you have to go slow ... and also NOT drop tang from coil into cyl ...

Dave

 

[noeettica]

Take the motor to a machine shop with an EDM Machine and have them do the helicoil ... Dave

 

[noeettica]

That's Funny My Motor has what looks like a Head ... That's just a water jacket cover ? ... AH Ha !

What kind of gasket / O-ring ?

Post a photo of yours ...

 

[noeettica]

I would Definatly go for the EDM on those
There is a thread here on Penatrating oils ... check with a local Merc guru They may have a "Drill Jig" for your motor a little heat and a lot of patiance are the key ... But Know when you are licked and when It's time to take it to the machinist ...

I may check mine and apply never seize Since mine is a basically new motor ...

You will not believe how long the Lower Unit Bolts are LOL ...