1960 40 hp Johnson

[willinokc]

Was going to pull the thermostat on the above engine since I thought it might be running hot, once I got the thermostat cover off I found a plastic sleeve and under that a half moon looking plug on a spring. I just want to make sure this is correct, except for the missing thermostat that is. I'm assuming the spring loaded deal is some kind of check valve.

 

[willinokc]

Re: 1960 40 hp Johnson

pic didn't post first time

 

[Vic.S]

Re: 1960 40 hp Johnson

The spring loaded valve is the pressure control valve. The cooling system is pressurised and that controls the pressure. The thermostat should be sitting in that sleeve which is the thermostat housing There probably should also be a gasket on that plastic housing.

Several variations on the theme exist. Some have the thermostat and pressure control valve side by side some use the thermostat itself as the pressure control valve.