1987 Force 125 in for Surgery.

deerslayer303

Petty Officer 2nd Class
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Apr 29, 2009
Messages
101
Hello All, Its been a while since I posted here. But a friend came to me about a week ago and asked for my help. He was at the lake and his 125 started knocking at half throttle so he shut it down immediately and was towed in. Upon initial inspection there is a lot of side to side play in the crank. I grabbed the flywheel and I can move it side to side ( like pulling up and down on each side of the flywheel). I can easily turn the fly wheel back and forth a bit with no resistance as if you were moving the crank and pistons. There is no movement in the rod bearings. I pulled the plugs and got each one on the downward stroke then with a wood dowel I tried to push on the piston to see if there was any slop. So anyway I pulled the power head today and I'm going to open her up tomorrow and see what the deal is. Sad too, I have been helping him along with advice on care, maintenance, etc since he bought the boat and this motor ran beautiful, appears to only be run in freshwater (VERY minimal corrosion on bolts etc when pulling the powerhead today) and looks to be a low hour unit. I don't know what happened. But we will soon find out. More to follow with pics.


Note: I love a Force / Chrysler outboard, My favorite being the 3 cylinder single carb motors. I have one on my 17 foot Bayliner Capri and I love that thing. Talk about simplicity. One of these days I want to find an Older Chrysler to play with
 

redstrat

Petty Officer 1st Class
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Dec 29, 2011
Messages
202
I'll tag along for the ride. I'm still breaking in my rebuilt 125. 7hrs and 44 minutes so far.
 

fisheymikey

Chief Petty Officer
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Jul 30, 2012
Messages
450
DO not remove powerhead until inspecting the Flywheel,, I had no time to update a few posts but to my experience the flywheel key needs to be inspected before you advanced... Sometimes the key gets loose due to vibration and improper torque
 

deerslayer303

Petty Officer 2nd Class
Joined
Apr 29, 2009
Messages
101
Redstrat, I read you entire thread on your rebuild, I have to say you left me wanting more though LOL. I'm glad she is running good for you though. I did inspect the flywheel as much as I could with it on the motor. Its seems all is in order and the thing will fire off so I'm figuring the flywheel key is intact. I've got the powerhead off and on the table. I didn't post a pic of it as I'm sure you guys know what that looks like haha. Anyway I am now fighting this flywheel. I've read some threads on here about these stubborn stuck flywheels. I've tried a 2 jaw puller, that didn't go so well it wouldn't stay centered, so I threw that one back in the drawer, I tried the regular steering wheel / balancer puller, well that just pulled the 3 bolts right out of the flywheel. And I've tried prying up on the flywheel with a bar and smacking the crank snout (with nut installed) No luck there just buggered up the nut (does anyone know the size and thread pitch of this nut so I can pick up another one for my next removal attempt)? Next I'm going to try Jerry's method of the BIG 3 jaw puller, hammer, impact, and Heat.
 

redstrat

Petty Officer 1st Class
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Dec 29, 2011
Messages
202
I think I would go back to the bolt on puller and re thread the bolts. I have a flywheel lying around with a big chunk out of it from someone using a jaw puller. I put pressure on the puller and then gently pry between the flywheel and the exhaust chamber. Keep tapping and turning the crank. Liberal amount of penetrant a given. Keep turning and tapping, adding pressure in small increments. It's a good feeling when she goes Pop!
 

deerslayer303

Petty Officer 2nd Class
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Apr 29, 2009
Messages
101
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Well I got the flywheel off finally. We used a big 7 ton 3 jaw puller, and using a 3 foot pull handle and socket we cranked it down, applied some heat with the little propane torch, then a few whacks with a 3lb hammer, and repeated the process till after EXTREME pressure from the puller had distorted the ring gear on the flywheel, one final good solid whack and POW off she came. I'm glad I had the nut on there as you guys are right that thing comes off of there with some FORCE haha.
Any way just as I had an Eerie suspicion the crank was broke clean in two in the #1 rod journal. The AMAZING thing is even #1 rod, the main journal, bottom of the cylinder NOTHING is damaged everything looks A OK. I was really amazed just by that. The cylinders on this old girl look FANTASTIC as do the pistons. SO I guess now the fun begins to locate a crank shaft, flywheel, and Flywheel nut. I gave the owner of the boat the block and all to clean up the gasket surfaces, LOL needless to say he is hating me and life right now.
 

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deerslayer303

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deerslayer303

Petty Officer 2nd Class
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My friend just sent me this pic. And I had to share it with you guys. I told him that if he keeps showing this much dedication to this rebuild, that this thing will be back on the water in no time. The FORCE is strong with this one.
 

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jjack010

Seaman
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Jul 21, 2014
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57
Wow, are the cranks on these weak? Machined too much? Operated under severe conditions?
 

deerslayer303

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Apr 29, 2009
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101
Not sure Jack about the cranks being weak. I don't think this one has ever been in to. And it looks as if she never starved for lubrication. I guess any casting can have a weak spot.
 

deerslayer303

Petty Officer 2nd Class
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Apr 29, 2009
Messages
101
Alright Guys, What crankshafts can I use in this 1987 Force 125? Model 1251X7B. Can I use the later Mercury/Force 120hp crank in this? I noticed Frank had a video on youtube with a 120 crank in his Chrysler.
 

Nordin

Commander
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Jun 12, 2010
Messages
2,428
I am changing the crank in a 70Hp 1969 Chrysler (3 cyl.) and going to use a crank from a 90Hp 1991 Force.
Have emailed Frank and he says every crank from a Chrysler/Force with NO Mercury gearcase will fit.
SO I think (but not 100% sure) that a crank from a 4 cyl. Chrysler/Force with Chrysler/Force gearcase will fit your Engine.
The Mercury gearcase has an other diameter and splines for the driveshaft..
 
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pnwboat

Rear Admiral
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Oct 8, 2007
Messages
4,251
Crankshafts from 1984 - 1989 125HP motors are the same. The stroke is 2.87in. Starting in 1990 through 1995ish, the cranks are almost the same...the stroke on these cranks are 2.80in. 1996ish - 1999 the cranks have a different size snout (larger in dia.) where the flywheel sits, so the flywheel has a larger hole in the center and typically has a lip that sticks up around the hole that is threaded on the inner circumference for a flywheel puller.

If you use a 1990 - 1995 120HP crank, the by-pass ports drilled into the side of the cylinders may not be optimized for the shorter stoke, even though it's only .07in difference.........I would tend to shy away from these unless you are willing to do some "experimenting" with the by-pass ports.

I would stick to the 1984 - 1989 cranks to be safe, but it's really your decision.

Having said that, I've swapped the 2.87in stroke into a 1990 - 1995 block and tinkered with the by-pass ports on my own personal motor with good success, but not sure I would do this for someone else unless specifically asked to do so. When you grind away the metal on the by-pass ports, it's kind of hard to put it back if you make a mistake!
 

deerslayer303

Petty Officer 2nd Class
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Apr 29, 2009
Messages
101
Thanks Guys, thats exactly what I needed to know. I'll stick to the 84-89 Crank. I've played with ports on other two strokes but its not something I want to get into on an outboard. I can't find a crank locally, so we are down to ebay. I don't really like the idea as I can't see it and inspect it prior to buying.
 
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