Stripped oil plug

[drunkgeo]

Been looking around the forum but have not seen an answer to the following predicament.

I stripped out the threads for the oil plug on my 2006 90HP 4-stroke. Looking for advice on what the best way is to fix the problem.

Should I tap the threads and buy the same plug?

Buy an oversize self tapping plug? Rubber plug?

Any other suggestions?

Thanks in advance.

 

[northernmerc]

Re: Stripped oil plug

Tapping or cleaning up the stripped threads and putting in the same plug likely won't work. The plug will just spin in the hole.

You don't say if this is a filler plug or a drain plug. Either way, you might want to disassemble the piece and then drill and tap the hole oversize. Then install an oversize plug.

You could drill and tap it without disassembling it, but then you might get metal filings into the leg. Or you might first want to try an oversize self tapping drain plug - if you can find the right size.

 

[Chris1956]

Re: Stripped oil plug

There used to be a brass "plug within a plug", that you could install. You might check with merc to see if they still have one. Once the outer plug is installed, the inner plug unscrews to drain/fill the gear oil.

 

[drunkgeo]

Re: Stripped oil plug

Yeah it's the drain plug.

If it gets to the point where I need to take the leg apart I think I will find a repair shop.

 

[drunkgeo]

Re: Stripped oil plug

There used to be a brass "plug within a plug", that you could install. You might check with merc to see if they still have one. Once the outer plug is installed, the inner plug unscrews to drain/fill the gear oil.

Thanks I'll look into that.

 

[northernmerc]

Re: Stripped oil plug

That sounds like an idea that is worth pursuing.

They do make the brass "plug within a plug" for the water drain holes on the side of mercruiser sterndrive engine blocks. My 4.3 liter has one on each side, and they work well in that application. The inner hole is quite small so it might take a while for oil to drain if used in your application.

 

[kend301]

Re: Stripped oil plug

Depending on the size , get a NPT tap and a brass plug that is the next size up . If you have to drill have a friend hold a shop vac nozzle next to the bit .. works well . Retap and install the new drain plug ..
Or you can buy a helicoil kit drill and tap then install the steel insert and use a new stock plug.
I personally avoid self tapping oversize plugs , They work great in a jam when you have no other options but will restrip the casing (from normal removal and installation ) and leak over time .

 

[Tim Frank]

Re: Stripped oil plug

Absolutely re-tap...carefully and try the same plug. Use a "forming" tap rather than a "cutting " tap.
It's a free shot and might work.
If it doesn't, you are no further behind and still have a choice of all the other options suggested.

 

[mla2ofus]

Re: Stripped oil plug

If you have to tap, try putting 5 psi air pressure in the filler hole while tapping. this will force any stray cuttings out.
Mike

 

[drunkgeo]

Re: Stripped oil plug

Absolutely re-tap...carefully and try the same plug. Use a "forming" tap rather than a "cutting " tap.
It's a free shot and might work.
If it doesn't, you are no further behind and still have a choice of all the other options suggested.

Good idea. -40degrees here in Manitoba, have to wait a few weeks before I try to fix this screw up.

 

[Tim Frank]

Re: Stripped oil plug

If you have to tap, try putting 5 psi air pressure in the filler hole while tapping. this will force any stray cuttings out.
Mike

Great suggestion!