1992 Mercury 15hp Lower Units

[Chinewalker]

I recently took a 1992 Mercury 15hp in trade, knowing it needed lower unit work. Turned out the gears are roached.

My motor appears to have the "Type I" lower unit referred to in the parts books, which doesn't look to have much in common part number-wise with the "Type II" units. My question is, do the lower units interchange, as a unit? I'm looking for either a set of gears or a complete unit, so I'd like to cast as broad a net as possible as I peruse eBay, etc. If I'm stuck with looking for the '86 to '93 unit, that's fine, but if the Type II, which was made up into the 2000s, will work, too, then I don't have a problem looking for one of them, either...

Thanks!

 

[Chinewalker]

Re: 1992 Mercury 15hp Lower Units

Okay, now I'm confused a bit. Going by the parts book, my unit is a Type II (no spaghetti seal on pump base), BUT, it does NOT have a 2:1 gear ratio. It has 13:27 gears, not 13:26. Can the gears interchange as a set, within either type unit? Not finding many used ones on eBay, so I'll probably have to spring for new. I just don't want to get stuck with gears I can't use.

 

[oldman570]

Re: 1992 Mercury 15hp Lower Units

If you check into it a little father, I believe that the 9.9 or the 18 hp motors used the same LU but had different gears in them. JMO
Oldman570

 

[Chinewalker]

Re: 1992 Mercury 15hp Lower Units

Similar units were used on 8 to 15 hp models.

FYI, serial on mine is OD171758.

 

[Chinewalker]

Re: 1992 Mercury 15hp Lower Units

I never got a definitive answere regarding the 26 vs. 27 teeth gears, but I did find a parts motor with a good lower unit. I went to a NYS DOT auction yesterday and bought a 2000 15hp with something loose in the powerhead. Paid less than what used lowers were going for on eBay and lucked out. Oil was clean, unit shifted nicely. A new waterpump impeller and voila!!

 

[MH Hawker]

Re: 1992 Mercury 15hp Lower Units

Its all ways nice when you luck out.