Water pump problem???

[brunogreco]

I have a 40hp Mercury and recently on a trip water stopped shooting out of the hole. I replaced the impeller and had better water pressure than I'd seen on the motor since I bought it.......Ran it twice and the second time out after about 20 minutes I lost a considerable amount of water pressure. I got home and put the muffs on it and took the cover off the motor and there is a little hole on top of the motor that was shooting a little water out from time to time. I don't know what that little hole is and I don't know what that means. Any ideas what needs to be done would be appreciated!!!

 

[brunogreco]

Re: Water pump problem???

The little hole above is where the water was coming out of.

 

[rodbolt]

Re: Water pump problem???

its a pressure control diaphram and yours is bad.
not a hard nor expensive fix.

 

[brunogreco]

Re: Water pump problem???

I ended up taking that thing apart and now know it is the thermostat housing....the diaphragm was ok. I started tracing my water lines and found where the water stopped flowing. Took my lines off and put an air compressor to them and blew a little hunk of grass out of one. Problem solved. I am assuming the water was coming out of that hole because the pressure that built up made that diaphragm pop up like it is suppose to. Either way I'm back on the water. Thanks for the help!!!