What lower units are compatible with a 93 force 90hp

[Tommy2082]

I have a 93 force 90 with a bad lower unit. I was just wondering what year and horsepowers would be compatible with it. I found one off an 87 90 would that work. Thanks

 

[jerryjerry05]

Welcome.
There are 3 different units.
You need to ID the one you have.
Find a parts diagram.boatdotnet has them.
Under the Mercury tab.
​The lower section open the Force and find the year.
Find the HP and open that and you'll see the 3 models.
​A B C that will tell what type you need.
Post the type or if you have access to a photo sharing site post some pics of the lower unit.
After you post 5 times here they allow you to add pics to your posts.

I'm guessing at C
​The C model can use from 90-94 but we really need to see the lower to make sure.

I'm pretty sure the 87 probably won't work.

 

[SkiDad]

I'm fairly sure the 87 will work as long as its from a 87 force and not a 87 mercury engine - in 87 that would be a 85 hp force - the 90 hp didn't start until 1990 Anything from 84-94 force 85, 90 and 120 and 125 Force should be interchangeable as long as both are 20" or both are 25" - there were 2 lengths.

One thing to note the 80's lower units were single exhaust and came in 2 gear ratios - from an 85 HP they would have a 3 stamped on it for 3 cylinder and it would have a 2:1 gear ratio. From the 125 engine it would be stamped 4 for 4 cylinders and have a 1.73 gear ratio. the 85 hp lower would be a better choice. I actually have one in my garage right now.

 

[jerryjerry05]

Something about the area behind the pump housing that needed to be filled in on the later ones?

 

[Tommy2082]

I got the motor in trade and am actually tring to sell it i am having trouble finding the info on that site i will try to post pics thanks

 

[Tommy2082]

Pictures

 

[Tommy2082]

I will post pics

 

[Tommy2082]

Puting pictures up

 

[Tommy2082]

It still wont let me post pictures it keeps saying invalid file data

 

[SkiDad]

open your picture in Paint - resize it to 50% or 30% and re-save - sometimes the pictures are too big.

 

[Tommy2082]

Figured it out thanks

 

[SkiDad]

a force 85 hp lower unit will fit that as long they have the same length shaft - the one in your picture seems to be a 20" version. The one is your picture is a 2 piece shaft and the ones from the 1980's were one piece shaft so you definitely have to get it correct. My suggestion it to pull the lower unit off and measure it. Or just sell the motor as is for 300 bucks.