View Full Version : 120hp Force water in cylinders

03-08-2009, 06:53 PM
"I have 1996 120hp Force outboard. It idles just fine, but runs with little or no power. After running it I find water mixed with gas on the sparkplugs of the bottom two cylinders. When you look in the bottom two cylinders, there is milky fuel over the tops of the pistons. The compression in the cylinders was check and all had about 140psi each. Milky colored fuel comes out of the bottom carburetor when you tip the engine up after use. The top two cylinders look normal. We have checked the fuel supply and there is no water in the fuel. Would anyone have any idea where to start looking? Is this a cracked head, leaky gasket, cracked block? The engine has never been overheated."

03-09-2009, 12:38 AM
Pull the head and have a look. It will more than likely have to come off anyway.

03-09-2009, 10:33 AM
"After close inspection I could see a small dribble mark near bottom of head close to one of the head bolts. I Pulled the head. The gasket seems fine, although the gasket came off real easily. Head bolt near where I could see dribble mark was rusted far more than any other bolt. I also pulled the side port cover and cleaned out the milky mess of fuel/water mix. Pistons/Cylinders looked fine. No scoring or gouges at all. Slight scuff marks to one side on bottom cylinder. I guess I will just replace the head gasket and see if that fixes it. Any other things I should check while head is off?
Thanks much!"

03-09-2009, 08:33 PM
Maybe should have done a compression test before the tear down. It would be interesting to know the before and after results.
Good luck!"

03-10-2009, 04:55 PM
I did, 140,140,140,138. I'll let you know the after. I am curious as well.

03-11-2009, 01:25 AM
crack in block is the other bet

03-18-2009, 02:45 PM
"Well, I replaced the head gasket. No change! I inspected everything I could on the block for cracks and found nothing. Water appears to be coming in at the intake chamber area almost like it is coming in near the lower end of the crankshaft. I would not think that water would be in this area. Does anyone know if water gets up that high around the drive shaft that it would possibly come in from the bottom of the engine around the seals to the crankshaft?"

03-19-2009, 04:36 PM
"craig, check your exhaust plate for cracking. From what I understand ,they possibly have a problem with that issue, look it over real close ,and see if you find a crack in it. keep us posted as to what you find ,thanks turboman"

03-21-2009, 05:41 PM
I'd even step back a little further and simply try replacing the powerhead base gasket.

If it's shot (or the motor isn't torqued down properly) water could be getting where it shouldn't....

A base gasket is usually about 20 bucks and a bit of your time - although the powerhead is kinda heavy....

03-28-2009, 10:02 PM
"Graham, thanks for the sugestion. I did pull the powerhead and it is unclear if water is getting in at the base of the powerhead. I thought I would see something, but nothing apparent. I have the powerhead on my bench and will see if I can check the water side by putting about 5lbs of air on it after making a blank baseplate/gasket. It is still a mystery to me as to why water is getting in.



03-30-2009, 05:49 AM
"Craig look at the block where the bores are and you can see a steel sleeve that the piston runs in,this sleeve has alloy around the outside and if it has corroded away back to the steel liner it allow water into the combustion chamber"

03-30-2009, 11:01 AM
"Well, after much searching I found what appears to be the problem. Turbo_man pegged it right on, but I didn't look it over as close as I should have.

The exhaust plate has a crack in it. I did not notice it earlier because the crack ran along the line of the gasket and looked just like the mark from the gasket and since the gaskets are the same on both sides of the plate I never saw it until cleaning the plate to put it back on to pressure check the block. Even after cleaning, the crack is real hard to see even though it is about 3 inches long. You have to flex the plate to see it.

Thanks everyone for all the suggestions. I learned a lot on this exercise."

03-30-2009, 11:44 AM
"glad you found it ,Craig. These are sometimes very hard to find, but usually in the plate if you don't find the leak in the "normal places[lol].Like I said ,this model is the only one I know of that cracks there.Anyone else know of other models that crack in the plate?Thanks turboman"