Motor gear case drain screw stripped.

nettek · Mar 6, 2010

I bought a boat about a month ago and I recently changed the gear case oil on my Yamaha 60 OB. I was surprised how easy the lower screw came out. Well, when I finished filling the lubricant and went to tighten the screw it kept turning, it was stripped, not by my force :evil: .

My question is; I cannot tap it out larger to 3/8" thread because then the bolt head will not countersink into the hole.
I want to use a threaded compression bushing as pictured below.
Do you think this will hold? It is in nice and tight but I don't know what kind of internal pressures there are when the gears are spinning at high speed.

Any other suggestions/ideas are greatly appreciated.
Thanks.

nettek · Mar 6, 2010

let's try the pictures again...see below

nettek · Mar 6, 2010

lswoody · Mar 6, 2010

Not really sure. Before I took a chance with it on the water and risk major foot problems I would take it to whoever you use to repair your outboard. I'd be sure it was a certified marine mechanic too. I just wouldn't take a chance. Times are hard and money is hard to come by for most of us. Better to spend a little now and get it right, rather than take a chance and spend alot later.

KMixson · Mar 6, 2010

Can you get a Heli-Coil into it. I would trust a Heli-Coil over a threaded compression bushing. I accidentally drilled a hole into the water jacket on the head of my pick-up a few years back while installing a Heli-Coil in one of the exhaust manifold bolt holes. It has held with no problems under 13 PSI system pressure. I don't think the lower unit is under that much pressure when running. If you do use the compression bushing, I would suggest using a "crush washer" (copper or brass washer) under the lip of it.

nettek · Mar 8, 2010

Thanks for you help.
My solution was to drill and tap it out to 3/8-16 thread and get a round head bolt for it and grind down the head to fit. It seals nicely, does not leak but sticks out about 1/8". I don't think that would be a problem I hope.

Thanks again!

https://i692.photobucket.com/albums/vv285/nettek8/P3080001.jpg?t=1268025499