View Full Version : 1991 Force 120HP lower unit

06-29-2009, 10:36 PM
"How difficult is it to replace the lower unit on this motor? I'd like to save a little $$ if it's not too bad. Is the water pump installation tricky too? I read where there are some pinions that could cause grief if the pump isn't positioned correctly.

Also, does anyone know where I can find another lower unit without spending $1000+ on it?

Thanks in advance!


07-05-2009, 01:03 PM
"Is there a problem with your lower unit now ?

If there are seals that are leaking they can be replaced, at that time check out the gears and bearings.

If the engine has been run of left in Salt water then you would have corrosion in there and that can make things tricky."

07-07-2009, 12:20 PM
My lower unit cracked and seized up. I need to replace the entire thing.

07-14-2009, 03:18 PM
"I have a replacement lower unit from a 1993 Force 120HP, and everything is identical except for a rubber tube with a fitting on the end of it. The tube runs down the front of the unit and looks like it's supposed to connect into the motor column somewhere. My old lower unit didn't have this tube.

Does anyone know what it is?"

07-14-2009, 03:47 PM
"only tube is from the impeller to the powerhead for cooling, could be your tube is still up inside ?"

07-14-2009, 05:39 PM
"Mine doesn't have a tube or the module it connects to inside the lower unit. I'm stumped, because my repair manual doesn't show anything like it in the repair process."

07-15-2009, 09:18 AM
"do you have any pics ? What's your model and serial number ? I'm working on a 125 right now, just repaired the steering on it.

Suggest you goto www.crowleymarine.com ("") then parts catalog, then from the Mercury Tab choose Force, then pic your year then model number to check out some pics of your gear housing.

let me know what you find"

07-15-2009, 05:33 PM
"A local repair shop said that it was for the speedometer and that I can just wad it up and not use it in my motor. Does that sound right?

Thanks for that link Brian! That's very handy to have. It's the same schematic that's in the repair manual, but it also gives the description of each part. Good stuff!"

07-15-2009, 07:37 PM
"yes, that makes sense now, yea, zip tie it so it stays out of the way, if your PITOT breaks you can use the one from the outboard, should give you a more constant reading if you care.

you're welcome, crowleymarine is my fav for looking at stuff, good interface if it's not tooo old."