Force 120 with low compression seeking advice

[jdamron]

Re: Force 120 with low compression seeking advice

Wonder what the heck that's from??
Rubber? Plastic?

Yes I was surprised to see it there. It feels like hard plastic. I am thinking maybe it is from the upper cowl. The upper cowl has some areas that look like have been repaired. Maybe a piece came off and was sucked in?

 

[Jiggz]

Re: Force 120 with low compression seeking advice

It's amazing how much junk has been pulled into the intakes, first there was a ball bearing and now a large chunk of plastic! You can try pulling out the top piston while waiting for the lift ring. It takes nothing but two bolts and you can just simply push it out of the cylinder and get some closer inspections. If the rings or piston is messed up that will give you lead time to order the replacement parts. Just make sure you account for all the rollers from the cap bearings.

 

[jerryjerry05]

Re: Force 120 with low compression seeking advice

A chunk that big?
Getting past the carb cover then getting past the butterflies?
The damaged piston is on the top and this was found in the lower.
I imagine it was just laying there and not doing nothing.
Maybe it was a Monday morning motor?

 

[Jiggz]

Re: Force 120 with low compression seeking advice

Understood this chunk of plastic came off the lower carb and totally isolated from the upper carbs. But since the initial problem is on the upper cylinder and while waiting for the lift ring, it doesn't hurt to pull out the #1 piston. Who knows, after all those surprised findings you had so far you'll never know what you might find for more!

 

[jerryjerry05]

Re: Force 120 with low compression seeking advice

When I was a kid(long,long,long time ago) I worked at GM's engine plant.
They had a section that showed some of the "stuff" they found in "new" motors pulled from the line.
There was bolt's and nuts and paper and cigarette butts and condom wrappers and a beer can and lots more.

 

[jdamron]

Re: Force 120 with low compression seeking advice

Yeah, I have no idea what I have going to find next.

I have not had a chance to take off the top piston yet - just another super busy work week. However, the Lift Eye did arrive. But I just went out and looked at how it is to hook up and I just don't get it. This is the part number 91-90455 per the clymer manual that I should use and I was expecting it to thread into the top of the flywheel. But now that I look at it it does not seem to fit - I can't find any threads that it could thread onto. Please see picture below. Does this look like the right part? Do I just need to take off the flywheel nut first or is it possible all the threads in the flywheel have corroded away? Or am I just missing something?
Thanks again.

 

[pnwboat]

Re: Force 120 with low compression seeking advice

That lifting tool is made for the later style 1996 - 1999 flywheels that have an internally threaded lip that sticks up around the center hole.



I ran into the same problem as you did, so I just took some rope and a cherry picker on my 1988 125HP motor.

Later on I had a 1992 150HP motor to work on and the rope idea didn't work that well with the extra weight. I ended up making something similar that screwed onto the crank shaft snout. You have to remove the nut that holds the flywheel on to get enough thread to get a good bite. Worked great. Don't know if you have the ability to make something like this, but it gives you an idea.

 

[Jiggz]

Re: Force 120 with low compression seeking advice

I wonder if the inside of the lift rig you have is threaded and matches the shaft? If it does, maybe removing the nut will do the job.

 

[jdamron]

Re: Force 120 with low compression seeking advice

Thanks for the replies. No the inside of the lift ring I have does not have threads and it would be too large anyway, but that is how I thought it would have worked when I ordered it. I might just have to return it and try rope instead. What pnwboat made looks nice but if rope will work that might be faster. Thanks.

 

[Big Fish Billy]

Re: Force 120 with low compression seeking advice

On mine I took Jerryjerry's advice and got three screw eyes and threaded them into those three holes surrounding that main flywheel nut. Mine were 5/16 x 18 thread. It's not that you need help lifting the powerhead off, but it's nice to be able to lower it slowly, after rebuilding, and line things up on the way down.

 

[jerryjerry05]

Re: Force 120 with low compression seeking advice

Thats the wrong tool.Not ever gonna work.
The top of the flywheel is really rusty???
Spray some PB Blaster or WD on the nut.
Then thread chaser the holes.
Then get an eye bolt for lifting.

 

[jdamron]

Re: Force 120 with low compression seeking advice

Okay thanks for the advice on the lift ring. I will try to return it and see if I can find three eye bolts instead.

Okay regarding the top piston removal - I finally got it done today. It was not as hard as I thought it would be, but it seems it would be challenging to get all those roller bearings back in to put it back together this way. Anyway, I am not a mechanic but I do not really see any damage to the piston that I can tell. However, I did find something weird. Wrapped around the crankshaft behind where piton one attaches there is a clump of what looks like melted metal and there is a metal cord like material wrapped around it. I tried to get best pictures I could. Any idea what this is from? Does it look like something inside is coming apart or more foreign debris? Could this be why the starter motor had such a hard time turning? And could this affect compression in cylinder #1? And I guess the million dollar question is do you think I can remove this and put it back together, or is this just more evidence the power head needs to come off the boat and have a full overhaul?

 

[Jiggz]

Re: Force 120 with low compression seeking advice

I guess every opening is a surprise finding! It's time to stop speculating and time to get down and dirty. Remove the powerhead and do a full open and inspect and a full rebuilt. I'll take Jerry's offer in rebuilding it unless you want to do it and learn along the way. As for that "molten metal like" thing, only one way to find out. JB weld? Epoxy? or really metal? Use a magnet to find out.

 

[jerryjerry05]

Re: Force 120 with low compression seeking advice

Will that piece come out?Magnetic?
It's possible when they cast the block it was a leak in the form and molten aluminum leaked out and it just never got caught by inspectors.
It's in a spot that really wouldn't matter.
The cylinder will need to be bored.
From the scoring or marking it's not real bad but shouldn't be used.
FYI.The bearings get assembly grease to keep the bearings in place as you put them back together.
Normal grease is too thick and can actually heat up the bearings.

 

[Jiggz]

Re: Force 120 with low compression seeking advice

Let me include something, if you decided to do a full rebuilt which is highly recommended in this case, the piston cap re-assembly will be a walk in the park.

 

[jdamron]

Re: Force 120 with low compression seeking advice

Thanks again everyone for sharing your experience and advice. So at this point I think I have all linkages, wiring, and bolts disconnected. I got loose the six bolts securing the motor keg to the power head today and it went easier than I thought. Note I only cleanly removed two studs. But the remaining 4 nuts and lock washers just loosed easily off of their studs. I am assuming leaving those four studs in is not a problem since it seems those studs should just slip though the holes in the motor keg.

So anyway I want to rent a lift before lifting off the motor but I thought I would try to loosen the connection first so everything would be good to go when getting the lift. But I can't seem to break the connection. I can wriggle the lower cowl easily around. But I can't seem to find a good place to pry since the cowl is plastic. I can work a pry bar under the intake manifold but there does not seem to be any good place to pry there - see first screenshot below. And I tried putting a 2 / 4 on the studs and using a small sledge hammer to hammer upwards but so far that is not working - it is trough to hammer upwards. Anyway I was wondering if any of you had any advice for breaking this connection or any techniques that work. Thanks.

 

[jerryjerry05]

Re: Force 120 with low compression seeking advice

Being real careful at the back below the head and between the exhaust plate.
There should be a place to put a pry bar.
You have to be VERY careful not to score the mating surfaces.
You sure ALL the bolts and screws are out?
They might have hidden one at the back???

 

[Big Fish Billy]

Re: Force 120 with low compression seeking advice

I would get your lift set up and get a little upward pressure going on the powerhead. Then with your wood block tap up on your studs. From the look of your pictures, you have a bit of corrosion going on around those studs likely making things tight, some WD-40 wouldn't hurt. And as jerry said make sure you have all the bolts out.

 

[jdamron]

Re: Force 120 with low compression seeking advice

Okay so I used the lift and eye bolts as suggested in this thread and I only had to give it one good tap with a hammer against a wood 2 x 4 against the block and it came right apart. :joyous: I have posted pictures below in case this helps anyone else. So now I have it safely in the garage and I can start work on taking apart. One question I have at this point is should I do anything special to keep water or anything else from getting down into the openings of the motor leg? I do have the cowl secured over it but just wondering since it will be a while before putting together if I should put something else over those openings.

The 5/16 eye bolts as suggested in this thread worked great:

The wheelbarrow in the background was used to move it from back yard to garage. It actually was not too bad.

 

[Jiggz]

Re: Force 120 with low compression seeking advice

Congrats, you did very well! Keep us updated, after so many posts and discussion the forum is eager to find out the verdict on the slightly low compression on #1 and the misfiring. Thanks.