Mercury 50HP water leaking out of housing

[smudge]

I have a 1992 Mercury 3 cylinder 50HP and it is squirting water from a hole in a housing on the top of the motor - same side as the throttle linkages. I presume this is the thermostat housing.<br /><br />The hole in the cover is about an eighth of an inch in diameter and looks like it is meant to be there. <br /><br />Any ideas?<br /><br />Thanks.

 

[Elmer Fudge]

Re: Mercury 50HP water leaking out of housing

From what you're saying,it could well be the t-stat or the bypass valve.<br />Is your motor overheating?<br />Try replacing those parts and see what happens.<br />If you have'nt got a service manual,get one before you do anything,it'll aid you in parts identification and procedures

 

[rodbolt]

Re: Mercury 50HP water leaking out of housing

hello<br /> your pressure relief diaphram is ruptured. while your in there change the tstat and seal as well.<br /> good luck and keep posting

 

[smudge]

Re: Mercury 50HP water leaking out of housing

Thanks for the replies. I think it has been leaking for some time as the bottom spark plug hex rusts quickly and has done for the last 2 seasons, was only when I ran it with the cowling off that I saw why. The motor runs very well, no overheating, what is the pressure by pass there for?<br /><br />Will it be ok to use the boat in the meantime? I use it every other week at least and I think I have been motoring around with it leaking anyway.

 

[Elmer Fudge]

Re: Mercury 50HP water leaking out of housing

When your motor is running at high rpm's, the bypass valve also known as the poppet valve opens to allow a larger volume of water to flow through the engine block thus keeping the motor cool.<br />At lower speeds and rpm's,the valve is closed thus the t-stat controls the temperature for optimum performance,hence no excessive carbon build up and the spark plugs remain unfouled.<br />An excellent addition is to install a water pressure guage,in my opinion it is much better at giving you an immediate analysis of the performing condition of your cooling system.

 

[catmania]

Re: Mercury 50HP water leaking out of housing

I have a merc inline six, at the top of the motor is a hole, screwed into that hole is a hose, the hose runs up to my dash where a gage displaying my motors water pressure is located. This has save my motor more than once when kelp or what not clogged the water intake. My water pressure usually reads between 4 and 9 pounds.<br />It increases as revs increase.<br />If you got the hole i would get the gage its a motor saver.