how is water getting under my motor cowling

[floatmiboat]

I'm having problems with water getting under the cowling of my 25 hp merc and it's saltwater so it's causing some corrosion. I usually run out 3 or 4 km's full speed to go fishing and when I pull the cowling off it's all soaked on the bottom, inside the cover and even the lower spark plug boot is a bit wet. I can't figure out how it's getting in, but I think it must be spraying up in there somehow. Any ideas? Thanks

 

[floatmiboat]

Re: how is water getting under my motor cowling

could anything be leaking under full throttle but not at idle?

 

[Texasmark]

Re: how is water getting under my motor cowling

Water pressure is like 3 to 10 or so psi over that range. Doubt you would have it at WOT and not see something at idle especially when you say it's soaked. If you have a gasket leaking and it's salt water I'd think you'd see some corrosion around the edge of a gasket if leaking. Main sources would be the water jacket cover over the pistons and the exhaust manifold water jacket cover. Or, in an unusual instance, a bad seal where the power head attaches to the mid section.

Why don't you take the cover off,hood, bonnet, cover, upper cowling, whatever you call it and run it so that you might see where it's coming from. Maybe you could have someone drive while you look.

Mark

 

[floatmiboat]

Re: how is water getting under my motor cowling

Water pressure is like 3 to 10 or so psi over that range. Doubt you would have it at WOT and not see something at idle especially when you say it's soaked. If you have a gasket leaking and it's salt water I'd think you'd see some corrosion around the edge of a gasket if leaking. Main sources would be the water jacket cover over the pistons and the exhaust manifold water jacket cover. Or, in an unusual instance, a bad seal where the power head attaches to the mid section.

Why don't you take the cover off,hood, bonnet, cover, upper cowling, whatever you call it and run it so that you might see where it's coming from. Maybe you could have someone drive while you look.

Mark

Ok, thanks, I'll try that after work and post back.

 

[floatmiboat]

Re: how is water getting under my motor cowling

I tried running the motor at idle in the ocean and then running it in gear with the cover off and couldn't really see anything. Put the cover back on and ran at full throttle for 5 mins, stopped pulled the cover off and there was water pooled in the bottom. Still can't figure out where it's coming from.