Force 125 lower unit issue

[Zack Of All Trades]

I have a Force 125. It was working fine and performing really good. Family member took it out and it stopped going forward when he we out on the water. Now he didnt go full send because he had kids on board i think it just randomly quit.

Uppon inspection i noticed the following:

Gear fluid leaking around the prop.
When i drained gear fluid it was super milky.
And when I tested it it went reverse but no forward.
I removed shift cable and tried shifting into gear manualy, reverse engages but no forward.

My question is: Can I rebuild lower h jt, how difficult is it? I also have a force 85, are the lower units interchangeable? I like the boat with which the 125 came and I like the performance of the 125 i wouldn't mind the Bayliner capri and its 85 be a donor it its compatible.

Any help is nice thank you!

 

[Nordin]

Please check the model number on both and post those.
They should be interchangeable, but there was some different LU.
Single exhaust and dual exhaust, one piece drive shaft and two piece drive shaft.
2:1 or 1,93:1 gear ratio.

 

[Zack Of All Trades]

Please check the model number on both and post those.
They should be interchangeable, but there was some different LU.
Single exhaust and dual exhaust, one piece drive shaft and two piece drive shaft.
2:1 or 1,93:1 gear ratio.

One of the boats has the serial number scratched off :/ but these are the pics i got. Is it too terrible to change seals and forward gear? Im mechanically inclined and i dont mind buying tools as i flip boats and cars.

 

[Nordin]

The second and fourth pic are the 85Hp and it has the single exhaust LU.
It is a 1988 year model.
Is the 125Hp LU a single exhaust LU or a dual?
I think they are interchangeable, but the gear ratio can be different.
It is easy to check the ratio.
Pull the plugs and turn the flywheel one turn and check how much the prop turn.
One turn of the flywheel and the prop turn half a turn then it is a 2:1 gear ratio.
One turn of the flywheel and the prop turn almost but not half a turn then it is a 1,93:1 gear ratio.

 

[jerryjerry05]

The gear ratio was different on the early Chrysler/Force 85/125
Then in the early 90's they used the same gears on the 90/120/150
The drive will swap the performance on the 85 won't be as good as the 125
The rebuild on the newer lowers is fairly easy.
They had a simple system to ID the housings.
You need a newer manual for that.
The 85/125 needs special tools for a rebuild, finding them might be hard, again the manual for the early years will be needed.
Take the gearbox apart and check the damage??
Sometimes the seal around the shift shaft gets corroded and locks up and won't shift (maybe)?