120 HP Force 1995 power head rebuild

[GLORY]

Force outboard 120HP SN:OE102939
Hi forum, The powerhead broke a conrod and damaged the crankshaft over a long period. I bought the boat 2 years ago, always had minor issues, not starting, bad idle....so after 2 years and about 15 hours it stopped completely. I took the head off and to no surprise I could see why I always had issues, not me
I disassemble the the powerhead to look for more damage then found the broken conrod, needless to say I could not even find the conrod bearing, the only evidence I could found were some nuggets on top of the piston. Now I need parts. Being in New Zealand does not make things easier so I would have to get all the parts from the US( all parts are avail), therefore I need to find the correct part numbers.

I think I've got most of the numbers sorted. The only one I struggle with is the crankshaft(13 tooth spline). According to the boats.net website I need a 820319A. The number stamped on the crankshaft i removed is 817400 which is the number for a 1994 model. The conrod, piston(bottom guide)3.375', wristpin 17.5mm and crankshaft bearings are all the same for a 1994/1995 model.

Now the million dollar ? Would it matter if I use anyone of these cranks?
I thank everyone in advance for your input.

Here are some pic's of the damage

 

[Nordin]

Piston, conrod and crank looks really bad. Have you checked the bore in the cyl./powerhead? Is it scored or bad scored?
You have to measure the bore and even check for out of roundness if you gonna put so much money in it as new conrods, pistons, bearing and crank.
If I were you I would check for a used powerhead/engine. It will be much cheaper.
Try to fine a parts engine, maybe it will be easier to fine one for example in Austrailia

Crank partnr. 817400 is for the earlier 125Hp and as you says 820319A for the 120Hp. I think they are the same and both will fit (hope Frank A will cime in and correct me if I am wrong) BUT the pistons are different. The 120Hp has a bigger bore then the 125Hp. 3,375 in (120Hp) and 3,312 in (125Hp).

Edit:
OOH! I looked closer to the pics and notice number one . Your engine has the Mercury style lower unit......... this puzzle me. You says the crank in the engine is 817400.
I thought Mercury changed the crank/spline when putting the new style lower unit in.

I have a 120Hp 1992 myself and it has the older Force dual exhaust LU and it has the Chrysler/Force crank.

Hope Frank, jerryjerry or jiggs cimes in and clear this up.

 

[jerryjerry05]

The 817400 is used in the 90-94 years.
Nordin. Not sure where you got the reference to a 125? 528018 is a 125 crank.
Not positive but I think in 95 is when they changed to the Mercury splines???

 

[sjbs]

I am pretty sure the 1995 crank is the only one can use because of the 13 splines. 1994 and older had 15 splines. 1996 and newer had larger rod journals and used Mercury rods and pistons,different flywheel and electronics.

 

[Nordin]

jerryjerry my reference is ishopmarine. 1989 125Hp for example. Yes , It says FA528018 and (400-817400T3). Also mercrusierparts does

But I am not familiar with newer Force then 1992 and does not know about number of splines on Mercury style engines.

 

[GLORY]

yes you guys are right, the mid and lower units are mercury. If you look at the pic's it will show the part number on the crank shaft and the 13 splines. What confuse me even more is that people sell these cranks(817400A) for a 120HP 1994 model on ebay and they also has 13 splines..The drive shaft for the 1994 #F694128 has 15 splines on the power head side.????

 

[Frank Acampora]

I hate to be a spoilsport, but given that the crank is useless, at least one piston needs to be replaced and at least one cylinder needs reboring, I say forget about repairing the engine and look for a used block with the 13 spline crank. I can not tell from your photos, but given that the con-rod is broken and bent and given that all the rollers and cages are gone, it is a reasonable guess that the cylinder is beyond re-boring. They can be re-sleeved but costwise with all the parts needing replacement you would still do better with a used block.

 

[GLORY]

Thanks for your view Frank,but I still believe that rebuilding would be my best option. You never know what you will get 2nd hand. The cylinder is not that bad, maybe I would have to go .020 oversize to get rid of all scoring. At least when its rebuild I know I have a good engine, hopefully for some time. To replace the crank and conrod (both 2nd hand)is only -/+ extra $400.

 

[GLORY]

Got this online

 

[pnwboat]

Hello GLORY, that attached image looks like it's from nwoutboard.com. I've purchased crankshafts from them in the past and they know Force outboard crankshafts very well. I put one of their cranks in my own motor about 6 years ago and it's been working great. I haven't had any dealing with them for a couple of years now, but in the past, they've been very helpful.

 

[GLORY]

image looks like it's from nwoutboard.com, yes it is pnwboat. Thank you I'll try and contact them for more info

 

[sjbs]

Sent you a private message.

 

[sjbs]

Looks like Mercury-Force built some 1994 817400c1 cranks with 13 splines to fit the Mercury lower units and used them in 1995.