1996 Force 120hp

[Erich1]

Just changed out my plugs and found moisture on one plug, replaced plugs took boat out for a test run, came home removed plugs and found moisture on two plugs (light brown goo) any ideas what it might be?
Thanks Erich

 

[jerryjerry05]

Re: 1996 Force 120hp

Head gasket??? Do a compression test.If the plugs are next to each other,it's probably a gasket.J

 

[pnwboat]

Re: 1996 Force 120hp

Which cylinders are affected? If it is water, then it could be a bad head gasket, or bad exhaust cover gasket. Bad exhaust cover gasket usually affects the lower cylinders (#3 or #4 ). Leaking water from a bad exhaust cover gasket tends to run down to the lower cylinders. Neither is hard to replace, however, use caution when removing the bolts. Sometimes they get corroded and may snap off if you aren't careful. Head bolts need to be torqued in proper sequence to insure a leak free fix. You might want to do a compression check to see if you have any significant variations in pressure which may point you to a bad head gasket.

 

[Erich1]

Re: 1996 Force 120hp

Head gasket??? Do a compression test.If the plugs are next to each other,it's probably a gasket.J

Did a compression test reading 145,150 150,148. The plugs run up and down. Going to check for waterr in my gas next.

 

[Erich1]

Re: 1996 Force 120hp

Its the top 2 plugs that are effected. Compression test was good with no more than a 5psi split between all cylinders. I do seem to have a heavier flow from my exhaust but the bottom 2 plugs are fine. Maybe water in the gas?

 

[pnwboat]

Re: 1996 Force 120hp

I doubt that it's water in the gas. It only affects the top two plugs. Same gas flows to all of the cylinders. Doesn't hurt to check though. How does the motor run? Is it easy to start?

 

[Erich1]

Re: 1996 Force 120hp

I doubt that it's water in the gas. It only affects the top two plugs. Same gas flows to all of the cylinders. Doesn't hurt to check though. How does the motor run? Is it easy to start?

Your right, after I sent the reply I thought the same thing. The motor starts right up and runs o.k. but I did notice it ran a little rough at wide open, backed off the throttle a little and it sounded good. But I know the wet gook on the top plugs is not right. I'm leaning toward changing the head gasket.

 

[pnwboat]

Re: 1996 Force 120hp

I would do the head gasket first. The head gasket is really easy to change. Again, use caution when removing the bolts so you don't snap one off. When re-assembling use some anti-seize compound on the head bolts and torque in sequence. Engine serial number OE138600 and up, torque to 120 in.-lb then turn an additional 90?. Engine serial number OE138599 and lower, just torque to 225 in.-lb.

 

[TwoFish]

Re: 1996 Force 120hp

As far as I have been told the 120 lbs and turn 90 degrees is a method call ?torque to yield?. It stretches the bolts. You need to replace the bolts with new ones each time.

From what I have read this method overcomes the problem of threads binding when tightening and giving incorrect pressure on the head gasket. Unfortunately it requires replacing the bolts because you can only reliably stretch then once.

My motor uses this method.

 

[jerryjerry05]

Re: 1996 Force 120hp

120# of tourqe might be too much.Lots of different opinions on tourqe and bolt strech.
At 20# 0r225in# Factor specs on most Forces,there is probably no strech on the head bolts.Reuse them.
I have reused the bolts with no problems.
Use a thread chaser and make sure the hole and bolt are clean.
I've found antisieze and salt water turn into permanant sieze.A combination of antiseize and grease seems to work.
After you replace the gasket and run it you can re-tourqe if you want.It's not necessary.J