Logo
FULL SITE MENU

Newbie here. Force 125 to Force 125 straight swap?

H

Hallass

New member
Hello all. I'm extremely green to boating and need to find a replacement for an 89 Force 125. I found another good running 89 force 125. Should it be a direct swap or are there chances of differences? It is 2 hours away and want to make sure before making a long haul for it.
Thanks for the help ;)
 
The 89 to 89 should be a direct swap.
The only thing that "might" be a problem is transom clamps.
The 89 should be the bolt through clamps.
The older is the screw type and it's a possibility they used them.

The length of the motor is another to think about.
They made the 89 in 2 sizes. 20 and 25inches.
Measure the transom and see if they match.

If you sell the old motor parts??
I need the transom clamp section.
Not the trim motor just the rest.
 
Jerryjerry05 said:
The 89 to 89 should be a direct swap.
The only thing that "might" be a problem is transom clamps.
The 89 should be the bolt through clamps.
The older is the screw type and it's a possibility they used them.

The length of the motor is another to think about.
They made the 89 in 2 sizes. 20 and 25inches.
Measure the transom and see if they match.

If you sell the old motor parts??
I need the transom clamp section.
Not the trim motor just the rest.
Click to expand...

Ok, what im ending up with is a running motor head that needs a gasket, with a bad lower unit and 20 inch shaft that is original to the boat - and a then also a complete good running motor, but 25 inches. Is it possible to swap the midsection, lower units and shafts to make the good running motor the 20 inches or is that more work than its worth?
 
Your hull was made to run a 20"shaft motor,if jackplate can raise engine 5"s go for it. Its going to add some weight,something to think about. Remember cavitation plate on engine should be even with the keel on bottom of boat or darn close.
 
Last edited:
A jack plate would do the job.
The work to change the mid section isn't easy.
The parts are 30 years old and won't come apart easy.

What's wrong with the original motor?
 
Jerryjerry05 said:
A jack plate would do the job.
The work to change the mid section isn't easy.
The parts are 30 years old and won't come apart easy.

What's wrong with the original motor?
Click to expand...

The lower unit has a dead spot in the gears where it just spins freely and I haven't looked into the motor yet, but it does start and run. The p.o. said that he had a head gasket job done, and the upper gasket (valve cover? I know auto engines, but new to outboards) has a leak.
I may put an ad on Craigslist looking for someone to trade for a 20". Maybe I'll get lucky.
 
The p.o. said that he had a head gasket job done, and the upper gasket (valve cover?
Do a compression test.
No valves on a 2 stroker.
Upper gasket???
 
I'm pretty sure he just meant the head gasket. He was an inboard guy and said that this was the only outboard he had ever owned so Im guessing that since it looks like a valve cover, that's what he is referring to. It looks like there is rtv around it so someone may have just done a hack job and threw it on there instead of a gasket. I'll check compression tonight. I'm tepted to throw the good lower unit on it and try it just to see what it does. I was expecting to junk it or just save it for parts so at least I won't be disappointed.
 
I would consider just swapping the powerhead and the gearbox. You will need to reseal the gearbox any way so just swap the hard parts from the 20 inch to the new one shift shaft and driveshaft and new seals. One of those 1/4 inch cordless impact drivers works real well for disassembling older motors just get a socket adaptor and just tear them both down and use all the good parts on the 20 inch housing.
http://www.marineengine.com/parts/force-outboard-parts/125-hp-1989/1251a9e/gear-housing
It looks like the only thing you need to swap is the driveshaft for the gearbox. carefully lay everything on the bench as it comes apart paying close attention to shims. Once you remove the propshaft then you can swap out the driveshaft then put it back together with new seals. Do the same with the powerheads you can normally get one good out of two motors if one has good compression.
 
Looking closer the gearbox is just a direct swap as well all you need is a good upper driveshaft I would want to pressure/vac test it anyways before putting into service.
 
I did a little investigation tonight. The "bad" 20" motor has compression 135-135-130-128. The head was definitely off and had a new gasket put on. There is a watermark near the bottom of the head, but I think it is coming from one of the gaskets at the bottom of the motor, just underneath the head. I have a feeling they replaced the head gasket hoping that it would fix the problem.
The cables on this thing couldn't have been adjusted right either. I unclipped them and the end was loose on both, and the gear selector cable end actually fell off when I was pulling it out so it couldn't have been on more than a couple turns.
I'm going to mess with the "good" 25" motor tomorrow and see what it tests at. I may throw it on the boat just to get in the water while I yank the "bad" motor apart and try replacing some gaskets.
Does anyone know where to get a service manual for these things?
 
Swap the good gearbox off of the 25 inch to the 20 inch and go fishing. Unless I am missing something those numbers are acceptable. Within 10% above 120psi should run just fine. Did you torque the head down properly? I would try and get that one running then you still have the other powerhead for a backup you can cherry out if you think its necessary.
 
IF??? you change the drive shafts???
You'll need to shim the parts.
A direct swap might work for a while and might only last a week???
Mercury can sell you the service manual. Or e-bay(lots cheaper)
Clymer or Seloc are ok but lack the technical data needed.

You say there is a spot that lets the prop turn free?
I'd take the lower unit apart(any chunks of metal in the oil?) and see what damage is in there??
DON'T remove the screw on the side of the housing.
The drain plug is on the bottom and is an allen head set screw.

I learned back in 1986 that you NEVER use any air tools to loosen anything on an outboard.
Loosen them by hand FIRST or you'll be twisting the heads off a lot of screws.
The bolts have been in a corrosive atmosphere and they seem to soften and the heads will twist off real easy.
If they don't loosen by hand first then certain steps are needed to insure their removal.
 
Even with the 2 piece shafts it would need shimmed? I was hoping that I could swap the upper sections and go.

I am looking at the lower unit now, and I guess there isn't a dead spot. More like a lot of slop in the gears. Im not sure how much play is acceptable, but if i turn the input shaft, it moves a distance of 2 teeth before the prop shaft starts turning which is maybe 60°? P.o. said that he was running it and all of a sudden it just free revved and stopped moving...
I am wondering if the unit is actually ok and the shift cable that was about to fall off wasn't the culprit the whole time. Possibly it was just stuck in neutral because the cable wasn't adjusted right? That cable end just fell off as it was only on by a thread or 2. Unfortunately the p.o. drained the oil so I don't know what it looks like.
 
Last edited:
I just talked to the p.o. and the leak isn't where I thought. It might be a simple fix. The head gasket was replaced, but the top cover of the head (where the spark plugs are) was just sealed with rtv and water was seeping from it. It looks like I'm going to try replacing those gaskets again properly, throw this lower on, and see what happens.
 
My model/serial tag is faded and I cannot make out the last 2 digits. I found the tag on the powerhead that says 1258F9D , but that isn't listed as a model#? Everywhere I see jumps from 1258F9C to 1258F9E except for C1258F9D. The definitely is no C on mine. Are all of these gaskets the same? Also I don't see a listing for the head cover gasket. Does that just get rtv?
 
Another issue discovered. I've seen it on chevy cavalier heads. It loos like some of the bolts were replaced. They are about 1/4 " longer than the older bolts and are bottomed out which will actually torque to spec before they clamp the head all the way down. It looks like this is going to be a gift hat keeps on giving. I'm tempted to start stripping and putting parts on ebay because who knows what else has been done wrong to this thing.
 
Yea load it up and go for a ride!!
I have some head bolts if you need.
Just pay shipping. About $6 for a box from the PO.
IF? you take anything apart and install a different shaft you need to shim.
It's not that hard but you need the factory book to get the procedures and specifications.

Like you said the cable might not have been adjusted right.
Possible the clutch dog needs to be replaced.
No shimming needed there.

The model changes on most years means a simple change was done.
The gaskets were all pretty much the same year to year.

Yes just LIGHT sillycone on the water jacket
Too much and it can block the passages.
 
2016-07-26 07.27.46.jpg

Thanks for the offer on the head bolts, but last night before I left for work l found this once I started trying to clean up the surface. I thought it looked cracked in 2 spots and a little poke with a small pick revealed the ugliness when 2 chunks of the block around 2 & 3 sleeves fell out. It looks like it's a parts motor for sure now.
 
Actually it can run like that!!!

You just need to use silicone on the gasket and make sure it seals.
And there is no huge gaps between the head and sleeve.
 
Back
Top