Force 90 with steam cleaned bottom plug

[jaredmccardle]

Hey guys, I want to see if i can get some expert advice on what I should do to repair my motor. Thanks in advance for taking the time to read and reply.

We recently had the boat out on the water the past couple weeks and it was running fine, but I noticed a slight leak from the middle carb. I replaced the carb needle and it took care of that problem. Then, I removed the plugs and noticed my bottom spark plug is super clean. I did a compression check and got 150psi on all 3 cylinders.

Next, I took off the thermostat housing and found it was broken. It shot out with the spring when I was trying to pull it from the housing. It is possible that it broke then but I'm unsure. In the pic, I stuck it in the spring just to show how it was broken. It had a few small rocks mixed in with the thermostat, I'm guessing it was letting water pass through because the over temp alarm has never sounded.

Next, I removed the head and the gasket looked to be in good shape. I went ahead and ordered a new gasket and thermostat kit. Hopefully they will be here this weekend so I can get it back together.

On the head there is a cover plate attached that looks to be sealed with a gasket maker material. Should pry this apart to check blockages or whatever? If so what type sealant should I use to put it back together?

Any advice or comments are appreciated.

Thanks

 

[racerone]

Clean plug is due to -----No fuel / too much fuel.---Bad diaphragm on fuel pump ------No spark -----Bad / shorted plug.----Does spark jump a gap of 3/8" or more on all leads , yes or no ?

 

[jaredmccardle]

I have a spark tester and will run the test on all 3 cylinders this afternoon and report back.

 

[jaredmccardle]

I confirmed spark on all 3. When I took out the bottom plug the other day, there was milky oil on the plug. That's why I jumped to the conclusion that it was steamed clean.

 

[GA_Boater]

Don't know if a Force is the same, but a Mercury with a bad lower crankshaft seal can steam clean the bottom plug as reported quite often in the forum.

 

[pnwboat]

It's also not uncommon for the exhaust cover gaskets to leak causing water leak into the cylinders. The compression appears to be fine so I would take a look at the exhaust cover. Note...the exhaust cover bolts are 1/4 X 20 bolts. Very easy to snap off whem removing. Be very careful when removing the bolts if you decide to do so.

 

[jerryjerry05]

The lower crank seal shouldn't have anything to do with water getting in the cylinder.

I'd do a real god inspection on the head gasket you removed.
The bolts when they came out, any loose?
Get a straight edge and check the head for warp and check the block too.

I had a 85 and all cyl were at 150# and still one was wet and started missing.
Very TINY,TINY pin hole in the edge of the gasket.

I have a bore scope camera that reaches 3ft.
Harbor Freight $70
Drop the lower unit and look up inside the exhaust chest.

Like pnwboat said, the screw holding the exhaust cover are real fragile and if you just look at them they twist off.

 

[jaredmccardle]

Thanks for the replies good info.

All the bolts were tight. This was most likely the first time that they have been out since the factory, because they were painted over. I'm the 3rd owner of this boat so there's no tellin.

The gasket and thermostat should be here tomorrow. I'll make the straight edge checks and inspect the old gasket. If I find anything questionable, I will post pics.

Thanks

 

[Nordin]

Jerry I almost agree with you about everything that comes up at this forum.
But about a bad lower crank seal not to affect the lower cylinder getting water.

I have had a 30Hp Chrysler 2 cylinder engine with milky lower plug.
It was a bad lower seal at the crank. The water follow the drivshaft up and then through the bad seal.

But first a will suggest to do as you says, check the head gasket and the head from spots or warp.
then check the exhaust gasket as pnwboat says.
Be careful with the screws, they will snap very very easy.

 

[racerone]

A bad lower seal will allow water to get into the lower cylinder.-----And most motors have a recirc system that will spread the water to other cylinders.----Water inside a motor can be death to 2 stroke bearings !!

 

[jaredmccardle]

I definitely don't want my motor to die. Don't have the $$$ to buy new motor or boat. The kids are counting on it this summer and the crappies are biting now so I want to get back out on the water.

I put a builders square across the head and it looks straight as can be all surfaces are touching the edge. Gasket looks good I don't think it was leaking. From the pic water would have to leak from the top rectangular hole to the adjacent cylinder correct (orentation of the pic is opposite, top of pic is the bottom cylinder) ?

What is best way to clean the surface for the new gasket? Steel wool?