1996 120hp Force locked up

[murphylaw]

Ran HARD for afternoon, bro-in-law flying on tube (safely as can be), running great! New prop, Very happy! Six people and running 5000+/- rpm w/ no hesitation. Stop and switch a couple times for other daring people to go tubing. Get on plane for a few seconds and what I remember is engine just pulling down to a STOP. Being very cautious I try to restart and "click". Sit for a minute thinking about worst case senario, and try again. runs in neutral w/ vibration and pulls down to a stop again. just "clicks" on restart. Row home and put on trailer. Still warm, I did a compression test, 150psi all four cylinders. Milky oil in lower unit. Refilled lower and put boat/trailer in water at ramp. OFF/ON and all gear ranges for 30+ minutes. Fires right up easily like always, but has noticable vibration at times(not misfire, but almost a bearing growling noise/ vibration). Disassemble lower and found no obvious signs of damage.

Did I lock up engine from running hard? Can I still have good compression? I assumed lower unit locked up but now I'm not so sure. Seems like everytime I go out something breaks. (just did rectifier/regulator) Now this

 

[Frank Acampora]

Re: 1996 120hp Force locked up

If no obvious signs of damage are present, check the engine for blistered or discolored paint or other signs of overheating. It is possible to overheat and harden to a stop without damaging pistons and cylinders. After cooling down, the engine will start and run normally.

 

[murphylaw]

Re: 1996 120hp Force locked up

Paint on engine is excellent. No blisters. Borrowed boroscope and cylinder walls look okay, nothing excessive, but did see random scoring on all cylinders, but nothing that indicated a siezed piston at one time. I wish I would have tried to turn the flywheel at the time it locked-up, but, oh well. I'm doubting myself if it even locked up. There is a vibration that has appeared since purchase this spring. (Not misfire, but bearing/growling noise at idle.) I remeber it being quite a smooth/quiet (for a 2-stroke) engine when I first had it out this spring. Just before it locked-up I noticed that my vibration/noise was significantly worse. I assumed that was going to be my point of failure. Now I got nothing.

Frank, I am always one for preventive maintenance, and when something seems wrong, I like to investigate before some worse $$$$$ happens. If this was yours, would you teardown further (main bearings/ rod bearings) or just run it again and see what breaks. I don't have alot of time into this boat, but I do believe I have developed this vibration since purchase. I'm not concerned about rowing home again, but if something lets loose and destroys more components, Murphys Law will win again

 

[murphylaw]

Re: 1996 120hp Force locked up

Still no answers. Starts and idles fine. Still has vibration. Lower unit off. With all the spark plugs removed it still turns over by hand, but has almost a flat spot. Hard to describe, but roughly 12 times in one rotation by hand there is a detent. Not smooth at all. Is this my magnets on the stator? I will pull flywheel tomorrow. Anybody w/ answers? Compression is 155, 160, 160, 155. Thanks.

 

[jerryjerry05]

Re: 1996 120hp Force locked up

Test the coolong/overheat system.
Key on,ground out the orange/sensor lead.
It should make the buzzer sound off.
The bore scope:you said you saw scoring on ALL cylinders??
Tell us more??
Pull the side covers,fuel pump side.
Then look for damage on the pistons.
The gas/oil mixed right?
Drop the lower unit.
Then start it.Still making noise?
The lower,drain the oil again and see if there is more/any metal.
Chech the bearings under the WP.
Prop ok no chunks missing?

 

[murphylaw]

Re: 1996 120hp Force locked up

Ground temp switch-already done. working fine.
minor scratchs on cylinder walls, nothing that indicates siezed piston. Nothing that would catch your fingernail.
Yes, oil is mixed correctly.
lower unit is already off.
lower unit has been disassembled and no damage.
engine has been ran w/ lower unit off. modified garden hose and low water pressure. Has vibration still.

Anyone w/ force 120: Ever notice this difficulty to rotate engine by hand w/ lower unit, and sparkplugs off? Anyone chime in with help regarding overheating engine and still being able to run fine afterwards? I will update more tonight after flywheel is off. Thanks.

 

[jerryjerry05]

Re: 1996 120hp Force locked up

If the plugs are out it should be fairly easy to turn.
Plugs in should be a lot harder.
ANY scoring in the cylinder walls or on the piston skirts will make it harder to turn and be the death toll for this motor.

Remove the side covers and take some pics of the pistons.
My pistons have been in the same motor for 24 years and don't have any scoring or wear scuffs on any of 6 pistons.
I had trouble with the fuel system and removed the covers.Clean and clear
My fathers 1968 60/Johnson blew a head gasket back in 1988 it had 2 small marks on 1 cylinder wall.
He traded it that year and it ran for another 12 years.The guy who bought it used it and eventually sold it for parts.The head was still good.


Why did I tell that story??? I don't know either???

Old and senile???

 

[murphylaw]

Re: 1996 120hp Force locked up

Pulled flywheel and now turns over by hand smooth Just feeling the magnets fight me. I was actually hoping I found something. So, I got a good lower, good compression, no obvious signs of failure. An engine that fires right up, (w/ vibration/noise) and nowhere to go (besides taking it out on the water) I guess if no one else has locked up a motor and still had good compression after it cooled down besides me I will take it out this weekend. If ANYONE has some light to shine on this thread please let me know, or if I am over cautious and should just enjoy the rest of the summer.

 

[SkiDad]

Re: 1996 120hp Force locked up

did you check the stator resistance and voltage ?

 

[murphylaw]

Re: 1996 120hp Force locked up

yes

 

[murphylaw]

Re: 1996 120hp Force locked up

Pulled cylinder head for good measure. Perfect. The marks I saw w/ boroscope were just oil streaks that wiped off. No scoring Will update soon, after on the water. Cross your fingers.

 

[emoney]

Re: 1996 120hp Force locked up

You know what they say.....wait, what do "they say" in situations like these? Oh well, take that sucker out and run it. I can see why you'd be cautious, but it doesn't sound like you have anything else to check. I'm sure you said, but you have confirmed that it's cooling correctly now, that the t-stats are opening, etc. etc.? I'd be paranoid too, but if everything checks ok, you don't have any options but to put it to the water and hope for the best. Not sure I'd spend all day at 5200 rpm, however. Maybe be a little easier on it this time out, lol. These manufacturer's say that WOT is "x", but I don't think the intent was to spend all day there. Good luck and definitely update us afterwards.

 

[murphylaw]

Re: 1996 120hp Force locked up

Runs good... sort of. Took it out and idled around for awhile. Got up on plane and Same ol' situation. Died and would not restart. But it cranked, and cranked, and cranked. Primer bulb was okay (firm). Tipped engine up, and put back in water and it took off. Idled around for awhile. Fuel pump??? Still has rattle noise when revved up in neutral, Did not notice it when underway.

 

[Frank Acampora]

Re: 1996 120hp Force locked up

I have had two Force engines just lock-up tight on me and then restart. The first one threw a ring (top) and of course, when the broken piece cleared the exhaust port she started like nothing had happened. ---Except, compression on that cylinder was down to 60-80.

The second broke a prop shaft. Again, she started right up effortlessly. I didn't realize and ran the engine for a couple of weeks. Finally, after a day of cruising half throttle I decided to open her up and the shaft let go again. Upon opening the lower unit I found that when the shaft originally snapped, the break was uneven and the two parts of the shaft jammed together, loading the reverse gear. This wore the land in the reverse gear so eventually there was enough clearance for the shaft to spin freely at the break.

AND, a number of years ago I did see a Force that still ran with a snapped crankshaft.

 

[murphylaw]

Re: 1996 120hp Force locked up

Thanks Frank. Compression is still good, and I will be watching it very closely, after every run I will be checking it for some time. I had the propshaft in my hand and saw nothing, but thanks. I did read a thread from a few years ago about a broken crank. I tried lifting up on flywheel and noticed no endplay, so I imagine it is ok. I have new headgasket on order (reused old for now) and will do a CLOSE visual inspection of cylinders when it shows up.

Just to clarify it did not lock up this time. just stalled out. I'm thinking fuel problem now and kindof ruling out mechanical. It cranked for sometime and tried to fire briefly when choked. After I tipped engine up and then back down it fired right off. Thanks everyone for the advise. I can't wait to go out again!

 

[emoney]

Re: 1996 120hp Force locked up

Hopefully you'll find that it's been a fuel problem all along. Not that i'm wishing a fuel problem on you, lol, but it's a lot better than a "locking up" problem at least. Good luck!