Stripped upper plug for lower unit fluid. Mariner 8hp

I got a 8 hp mariner and the overfill hole in the lower unit is stripped. Any suggestions? Can I just try and find a rubber plug for it? Thanks.

what do you mean its stripped?

can you run a tap though it and clean it up?

I would not try a rubber plug, it builds up a little pressure and the plug will pop out

you may have to drill and tap it out to the next size, or maybe an npt tap and a pipe plug would work

but not a rubber plug

I have been using LOCTITE PC-3967 Stripped Thread Repair
to repair 1/4-20 threads in aluminum where there is not enough
metal to retap for a helicoil or tap to the next largest size.
I found a tube on ebay for $12.00 + 3.00 shipping.

The next option would be to have it welded up and retaped.
If you choose this route, I would suggest removing your gearcase
so you don't leave anything inside that could damage seals and stuff.


LOCTITE® PC 3967™ Stripped Thread Repair Kit makes
reliable thread repairs without drills, taps, tools, or inserts.
Restores worn, stripped or damaged threads and eliminates future
corrosion, galling, seizing, and rust. Allows up to 128 ft. lbs. of torque
between -65°F to 300°F. Permanently repairs stripped threads and
fasteners in five minutes (up to SAE Grade 5 English and 8.8 metric).






.

I had the exact same problem with my lower unit just a week or so ago. My mechanic replaced the bad screw* with a Heli-coil. He knows what he is doing. richg99

https://www.youtube.com/watch?v=RFYa6sjhh_E

p.s.he told me that a number of screws were marketed as replacements ( for Johnson outboards) and those screws didn't have the threads extending far enough. Hence, after being put in and out a couple of times, they caused the stripping problem themselves.

Here is ONE shown on Amazon ( might not be the right one for you).
https://www.amazon.com/Helicoil-5521-6-Coarse-Thread-Repair/dp/B0002SRDVE

richg99

Thanks for the ideas. For now, I put a little Teflon tape on the threads, put the screw back on and covered the exterior screw with silicone. It seems fine for now, but I'll look into a Permanent fix.