Changing lube in lower unit

[nitrogf]

I have a 1994 Mariner 115. Changing the lube in the lower unit. This motor has two vent plugs up top and the drain plug below. The front drain plug is locked...cannot get it loose. I am afraid i will strip the plug or break it...rusted tight. Can i change the oil with just the back vent plug out? seems like it should still work (slower)...but learning not to assume.

also, any tips on how to break the vent plug loose...tried everything.

Thx much!

 

[Texasmark]

Re: Changing lube in lower unit

Probably. The normal fill is to fill till the front hole vents and then close it and continue till the rear fills. It might develop an air bubble however and I don't know how large it would be nor whether or not it would affect anything. Not familiar with the internal passages but on my 90 after you fill the front and plug it it just takes like an ounce or less before the second hole starts bleeding so they aren't all that far apart from a plumbing stand point.

They make an impact screwdriver that is all metal and has a ratcheting head on it. You insert it into the screw and smack the rear with a hammer. I think I got mine from Harbor Freight. Have gotten out of numerous "jams" over the years with it.

HTH,

Mark