125 lower unit choices

[redstrat]

Hi, I've been spending some time trying to sort out my lower units and here are my questions.

All of these I got on trade for upholstery services. The first one I believe is off a 91 120hp. I know this won't work for the 125 I'm rebuilding but I wanted to test it before I sell it. At 10lbs it leaks around the plate over the shift rod. My question is, why is the seal kit listed for this unit the same as the other three when it appears very different?
The second one is of an 86 125. It leaks very slowly. A bubble about every 3 minutes out of the water intake. How is air coming out the water intake? Also this one has a bent skeg. What is the best way to set it straight?
The third one came off an 88 125 and has the two piece shaft. I have the shaft and coupler. This one held pressure for several hours. Broken skeg though. I'm not sure which ratio will work best for my 16' Checkmate. Also, does anyone know the correct part # for the water pump as it also appears different?
The fourth came off an 89 125, held pressure, but has a 25" shaft. Also has a broken skeg. Is this one worth hanging on to even though I would have to swap out the shaft?
Any input here would be helpful. Thanks

 

[pnwboat]

Re: 125 lower unit choices

On the 1989 or earlier units, it's hard to tell if it came off of a 125HP or an 85HP motor. They look identical. The way you can tell is the gear ratio. Put the lower unit into forward gear and mark the propeller shaft. Turn the drive shaft clockwise (looking down at the lower unit) and count how many turns of the drive shaft it takes to make the propeller shaft turn one revolution. If you turn the drive shaft about 1 3/4 turns to make the propeller shaft make one revolution, then it's the 1.73:1 ratio used in the 125HP motors. If you have to turn the drive shaft 2 turns to make the propeller shaft turn once, then it is the 2:1 ratio used in the 85HP motors. Personally I like the 2:1 ratio lower units. On my 1988 125HP motor, I put a 1988 85HP lower on and it really woke the motor up. Hole shot was better and all around performance was better. I had to switch from a 17 pitch to a 19 pitch propeller to keep the RPM's down at WOT though. The 1990 and later lower units were all 1.93 - 2.3 to 1 gear ratio depending on horsepower and year.

Seal kit for the 1986 is about $45 and not that hard to install. There is a seal around the propeller shaft itself and a couple of "O" ring seals around the bearing carrier that supports the prop shaft that may be leaking causing the bubble out of the water intake. The "O" rings seal the carrier assy. right at the water intake area. As far as straightening the skeg, just take a large set of pliers or maybe a large adjustable wrench and bend it back. Hopefully it won't crack. Be very careful if you decide to apply heat (propane torch) to straighten, as there are rubber seals in the lower unit that could be damaged from the heat.

Taking a unit in to have the skeg repaired runs about $75 to $100 what I've seen. That third unit looks like there might be enough skeg left to bolt on a skegguard, but they're not cheap either.

NOTE: That first unit that you refer to as a 1991 is most likely around a 1995 or later since it's the Mercury style lower unit.

 

[redstrat]

Re: 125 lower unit choices

Thanks for the help. The second (white) one is 1.73:1 and the third appears to be a 1.93:1. I will definitely reseal the white one. I was worried there may have been an internal crack. Any experience with epoxy vs bolt on replacement skegs?

 

[pnwboat]

Re: 125 lower unit choices

Epoxy won't work if you attach by gluing edge to edge. Only way this will work is if you weld it. Bolt on skegs will work fine if you have enough to bolt to.

 

[jerryjerry05]

Re: 125 lower unit choices

Like PNW said the newer is a 94??? The parts for the leaking plate is way different.
The 3rd is an 89 or 90? 2 piece shaft started in 89.
The 4th an 87/88 1 piece shaft.
Some drives had a number stammped on the casing and you'd be able to tell if it's a 125/85.
You'd need a manual to figure it out.It's in the specs for shimming the gear cases.

 

[redstrat]

Re: 125 lower unit choices

Thanks for the help guys. I found the seal for the first one, $6, so I guess I'll replace it and see if i can find a buyer. I also found the correct water pump kits for #2 and #3. Someone has offered me $200 for #4 (also a 1.73:1) with the shaft that is to long for my application. What would you do, keep it for parts, or let it go?

 

[pnwboat]

Re: 125 lower unit choices

If it were mine......unless I know that I'm going to use #4 for something right away, I'd let it go. The money would pay for any repairs needed to which ever lower unit I decide to use. But that's me.

 

[redstrat]

Re: 125 lower unit choices

Thanks pnwboat, you're probably right.

 

[Faztbullet]

Re: 125 lower unit choices

The first unit is for a 1995-1999 motor, need to check ratio to see if its a 3 or 4 cylinder model...

 

[redstrat]

Re: 125 lower unit choices

Thanks Faztbullet, It appears this unit is about 1.93:1. If you know what motors this will work on I would greatly appreciate it. I want to list it for sale and I'ld like to be as accurate as I can. Thanks for your help.