150 hp lower unit replacement

[bluebackfisher]

I have a 1992 Force 150 hp outboard. At the end of the season I went to drain the gear oil and only some water drained out and less than an ounce of oil. I pulled off the lower unit and the lower unit seem to be damaged and would not hold any pressure at all. Since the seals were shot and almost all the gear oil gone from the lower unit, I feel it destroyed gears and bearings inside and that I need to replace it with a used one from eBay. Can anyone tell me what is covering for Jeff type a or a B lower unit is interchangeable with type C, since it looks like the motor has a type B or C. The anodes are on the outside above the anti-cavitation plate, so I thought that it is a type C. Also, I was wondering if it’s the same lower unit on the 150 hp as the 90 or 120 hp have? I sure would appreciate some help And will appreciate your replies.

 

[Nordin]

All 90, 120 and 125Hp no Mercury style LU will fit your engine.
The gear ration can be a bit different.
There were three different ratio, 1.73:1, 1.93:1 and 2:1.
I suppose your LU is a two piece drive shaft style.
The Mercury style LU was from 1994 and up I believe.
BTW There are a post not long time ago when we discussed LU.
Think it was a 1989 85Hp in that post.

 

[The Force power]

I have a 1992 Force 150 hp outboard. At the end of the season I went to drain the gear oil and only some water drained out and less than an ounce of oil. I pulled off the lower unit and the lower unit seem to be damaged and would not hold any pressure at all. Since the seals were shot and almost all the gear oil gone from the lower unit, I feel it destroyed gears and bearings inside and that I need to replace it with a used one from eBay. Can anyone tell me what is covering for Jeff type a or a B lower unit is interchangeable with type C, since it looks like the motor has a type B or C. The anodes are on the outside above the anti-cavitation plate, so I thought that it is a type C. Also, I was wondering if it’s the same lower unit on the 150 hp as the 90 or 120 hp have? I sure would appreciate some help And will appreciate your replies.

Where are you located?

 

[jerryjerry05]

After the early 90's all the gear ratio's were the same.
You have to look up the parts diagrams(like I did) and find when they standardized the ratio's.

 

[bluebackfisher]

Where are you located?

Idaho

 

[bluebackfisher]

After the early 90's all the gear ratio's were the same.
You have to look up the parts diagrams(like I did) and find when they standardized the ratio's.

Hey thanks for your reply! Where could I look up the parts diagrams?

 

[bluebackfisher]

All 90, 120 and 125Hp no Mercury style LU will fit your engine.
The gear ration can be a bit different.
There were three different ratio, 1.73:1, 1.93:1 and 2:1.
I suppose your LU is a two piece drive shaft style.
The Mercury style LU was from 1994 and up I believe.
BTW There are a post not long time ago when we discussed LU.
Think it was a 1989 85Hp in that post.

Thanks!

 

[Nordin]

Look at Crowley Marine.
They have the diagram.
Search from your model number.

 

[flyingscott]

Have you looked at the gears? Are they bad? If the gears are good maybe just needs bearings.

 

[The Force power]

Have you looked at the gears? Are they bad? If the gears are good maybe just needs bearings.

The right tools & know how but A seal-kit for sure

 

[jerryjerry05]

Hey thanks for your reply! Where could I look up the parts diagrams?

Top of the Force forum. "SHOP" open that and it will lead to parts diagrams.
iboats, crowly marine and google marine parts.

 

[bluebackfisher]

The right tools & know how but A seal-kit for sure

Yeah, that’s for sure! I am very handy, but I don’t think I’ve got the tools to do a proper seal job and tear down. I found a decent sounding used lower unit on eBay and the pressure test numbers sound good but I’m not sure it will work. Here are some photos, please let me know if you think it will work on my ‘92 force 150hp. The lower photo is the original LU off my motor where it says driveshaft 6 (or 9) and forward gear 4. The upper photo is the replacement used LU where the driveshaft is 4, and the forward gear is 2. I have no idea what these numbers mean on the two lower units. Will the replacement used lower unit work? Any help would be much appreciated!

 

[Nordin]

I think it will fit, the numbers are for right lash for the gears.
The two piece drive shafts gear case had computer calculated gears and there was no value for the lash.
No procedure how to measure the lash, the digits at the gear case give you the information of which forward gear and pinion gear to use.
In my opinion a really bad design, but I have measured the lash at these LU and shimmed it by using the same method as for earlier (1978 and up) Chrysler one piece lower units and also other brands (Mercury) and it has worked.

 

[bluebackfisher]

Great! Thanks for that information!

 

[The Force power]

I have no idea what these numbers mean on the two lower units. Will the replacement used lower unit work? Any help would be much appreciated!

As Nordin already mentioned; these #s only matter for a tear down when changing the inner-gears and shimming.

 

[bluebackfisher]

As Nordin already mentioned; these #s only matter for a tear down when changing the inner-gears and shimming.

Thanks! I was hoping that they didn’t have to match the original LU, so that is great!
I have another question for you guys though, I pressure tested the replacement lower unit with the oil drained out of the gear case and the gear case held seven psi, but anything over that leaked out of the prop shaft seal. You could hear a little hissing sound, and I double checked with soapy water that I sprayed, and it was making bubbles. The other seals seem to be fine though with no bubbles being formed from the soap solution! The manual calls for 10 psi to be held for 5 minutes, but it would only hold seven psi for five minutes. Is that low enough to replace the prop shaft seal? I’d like to go ahead and replace the seal, but are there any special tools that I would need, and if so, what are they?

 

[The Force power]

Have you removed the water-pump cap? the drive-shaft seal could be leaking & check the shift-shaft seal also
Turn/move all shafts while checking for leaks
Check if the prop-shaft is straight?! no wobble ?
Your gauge could be "off" I know the manual says 10 psi but I never go that that high.
I do however pull the unit in vacuum to see if it holds, don't forget there are two pressures you're dealing with;
- oil leaking out
- water penetrating
In my opinion based on holding 7psi ( not leaking anywhere else?) I would not change the seal.
You may need a spanner-nut ti remove the bearing-carrier IF you have a type C Lower-unit

 

[jerryjerry05]

Fix it.
The leak's only gonna get worse.

The numbers on top the case are for getting the right gear set.
Someone was sharing a sheet with the gear sets and the way they were replaced.
I had it but someone wanted it more than I did
I think(memory sucks) that if it says 4 you order the set #4 it should have the correct gear set.

 

[bluebackfisher]

Have you removed the water-pump cap? the drive-shaft seal could be leaking & check the shift-shaft seal also
Turn/move all shafts while checking for leaks
Check if the prop-shaft is straight?! no wobble ?
Your gauge could be "off" I know the manual says 10 psi but I never go that that high.
I do however pull the unit in vacuum to see if it holds, don't forget there are two pressures you're dealing with;
- oil leaking out
- water penetrating
In my opinion based on holding 7psi ( not leaking anywhere else?) I would not change the seal.
You may need a spanner-nut ti remove the bearing-carrier IF you have a type C Lower-unit

Thanks, I’ll check that.

 

[bluebackfisher]

Fix it.
The leak's only gonna get worse.

The numbers on top the case are for getting the right gear set.
Someone was sharing a sheet with the gear sets and the way they were replaced.
I had it but someone wanted it more than I did
I think(memory sucks) that if it says 4 you order the set #4 it should have the correct gear set.

Thanks , I would like to replace the seals but I have never done that before. I’ll have to look into that. Does anyone know if there is a good YouTube video on this?