Fill/drain tread on gear box nearly stripped

[AndrewB]

Ive got a feeling the thread on my gearbox fill/drain screw doesnt have many oil changes left, any suggestions on how I can fix this problem. Looks like its had quite a lot of abuse in the past and is boarder line stripped. Any ideas? - 1986 135hp V6 merc

 

[andrewkafp]

Re: Fill/drain tread on gear box nearly stripped

Only the obvious one. You will need to tap an oversized thread into the alloy and replace the s/s screw with a matching thread. If you don't feel comfortable doing it, I would say a qualified machinist or repair shop would be able to fix it. Getting the replacement magnetic screw may be the challenge.<br />If you wanted to do a patch up job you could wind some teflon plumbing tape around the screw.

 

[OBJ]

Re: Fill/drain tread on gear box nearly stripped

G'Day Andrew. Sorry to hear about the malady yer in. Striping a drain plug ain't never fun.<br /><br />What ya' might try....get a tap of the correct size, coat it with grease (to catch cuttings), run the tap into the plug hole. Then install a NEW drain plug with washer. Might do the trick.<br /><br />One time I repaired a drain plug hole with JB Weld. (just got lucky really) I disassembled the gear case so I could clean the hole real good and make sure there was no oil left. I roughed up the plug hole a little and tried to keep as much of the old thread as possible. This was to help hold the JB Weld. I coated a drain plug with a film of grease then a coat of JB Weld. The grease was to keep the JB Weld from bonding to the plug. Then I screwed it into the plug hole and let it set up....hard. I removed the plug with little effort and cleaned the hole up inside and out. Worked. The darn thing is still holding today. But that's a "just in case the tap idea don't work" idea.<br /><br />Hope ya' get it fixed. Keep posting.