OMC Cobra

[Gearhead59]

I have an OMC Cobra outdrive, 1987. The middle drain plug is stripped out. Suggestions for fixing it please ? I think it may have been "fixed" before,...see pictures,....I think the Heli coil came out with the plug when I took it out. Also,.....what size threads are they ?

 

[harringtondav]

If the helicoil threads are still good in the housing, here is a hail mary fix. Clean the housing and helicoil threads with acetone. Grease the plug threads and insert it into the helicoil. Apply a small amount of red loctite 243 or green locktite 270/290 to the helicoil threads. Reinstall the assembled plug and tighten. Wait 24 hrs for the loctite to fully cure. Then the grease will hopefully let your remove the plug while the helicoil insert stays put. Don't forget a new seal for the plug after you top off your lube.

 

[Gearhead59]

Thanks ! I have never put a heli coil in,....didn't have any idea of how they work,...., now I understand after you telling me and reading up on them. I believe you are right, I should be able to fix it with not much fuss ! Thanks again !

 

[Scott Danforth]

my guess, who ever installed the helicoil never loc-tited it in place in the beginning

 

[Bondo]

Also,.....what size threads are they ?

Ayuh,........ 3/8" -16,.......

 

[Gearhead59]

Update 3-31-19. I have discovered that it was not a Heli-coil that pulled out, it was just threads from the housing that came out with it. Now What ? JB Weld, and re-tap ? I did purchase a helicoil kit, but the hole would be so big after drilled,....I know, the Heili-coil would fill it, but,....what ya'll think ! ? There are pictures on my first post.

 

[Scott Danforth]

then add helicoil and go boating.

 

[Gearhead59]

Upon further investigation, I believe putting a Heli-coil in would reduce the sealing surface too much,....take a look at the picture in my original post. If I drill it out and tap it to put a Heli-coil in there, there will not be much left for the seal to sit flush against,....the "flat" will be gone. So, using a Heli-coil is out of the question. I believe using JB Weld is my only option. Thoughts ?

 

[Horigan]

If it were me, I would do the heli-coil and use a larger flat rubber washer the same size as the drain plug head for the seal. There would be enough surface area after the heli-coil installation to provide a good seal.