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1997 40 hp force issues

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Ribsyj

New member
Got my first boat this week. A 1999 crestliner pontoon. It has a 40hp force by mercury on it. So first time out on water it was running little rough had a slight studder. So opened cover up and checked plugs. Bottom plug was little milky white. Cleaned and reinstalled. But also noticed water in the bottom of cowl and oil residue in there. So started it up and seems water and exhaust coming into cowl. Also noticed water coming from coming from between cowl and lower unit running down driveshaft housing. Previous owner said shop told him exhaust seal was bad and need to remove lower to fix. Got great deal on boat now to try figure out where to start. Any help would be awesom
 
The milky plug is not good :(
Usually a bad head gasket is the problem.
Pull the head and inspect the gasket.

The water/oil can be from the 2 seals in the driveshaft housing?
NOT an easy fix.
Get a FACTORY manual as the aftermarket ones suck and won't cover these repairs very good.

T
MTM3NDgx-93ccb723.png

he 2 seals #30 and #8 and #33could be the problem.
I'd replace all 3 just in case??
Factory manual a MUST!!
 
Last edited:
Jerryjerry05 said:
The milky plug is not good :(
Usually a bad head gasket is the problem.
Pull the head and inspect the gasket.

The water/oil can be from the 2 seals in the driveshaft housing?
NOT an easy fix.
Get a FACTORY manual as the aftermarket ones suck and won't cover these repairs very good.

T
MTM3NDgx-93ccb723.png

he 2 seals #30 and #8 and #33could be the problem.
I'd replace all 3 just in case??
Factory manual a MUST!!
Click to expand...

Thanks have service manual orderd. Going to do compression check today. Read that sometimes running it with water under cowl can cuz milky in the plug. I did notice milky around the carb after running for a bit. My dad has tore few outboard down in past and repaired them. I'll check compression and then most likely change those three gaskets
 
Did a compression test and have 125 psi on both cylinders. Ran with muffs kn and water is pushing out around power head base. Thinking the moisture inside the cowl was sucking in intake and causing the milky plug. Was very small trace. Working on removing lower to change and inspect gasket
 
Tore it apart and found the upper adapter gasket to the power head blown out. Lower seal number 33 looks good. Upper one is little shady so going to
Change that one and number 8 and both adapter plate gaskets.
 
1988/85 hp missing.
Did comp test and had 145 all 3 cyl.
Pulled the head and had a pin hole in the sealing ring.
Had a drop of water on the plug.

The "
Thinking the moisture inside the cowl was sucking in intake and causing the milky plug. Was very small trace"​
Moisture being sucked in and condensing on a plug? You'd probably have water on both plugs.
It's something to look into after the other gaskets are changed.
 
Jerryjerry05 said:
1988/85 hp missing.
Did comp test and had 145 all 3 cyl.
Pulled the head and had a pin hole in the sealing ring.
Had a drop of water on the plug.

The "
Thinking the moisture inside the cowl was sucking in intake and causing the milky plug. Was very small trace"​
Moisture being sucked in and condensing on a plug? You'd probably have water on both plugs.
It's something to look into after the other gaskets are changed.
Click to expand...



Thanks I will keep an eye on it and see what happens after it's all back together. If continue to have water in plug i will pull the head
 
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