No Thermostat ?? Is it possible ??

[Bottomline]

87' 150 BlackMax
Been having occassional alarm go off. So I started doing some investigation. I bought this boat used, and it runs fine usually except for the alarm kicking in sporadically.

The impeller kit was replaced this spring, and I'm getting a solid stream of water from the pee hole.

I pulled the cover plate for the starboard side thermostat - and no thermostat only a rubber gasket in need of replacing. So I figured its only supposed to have one thermostat and opened the port side. Again no thermostat (yes another gasket looks shot).

Does that make sense? Should there be any thermostats on this motor? Is it somewhere else?

Thanks
John

[MTCM]

There should be Thermostats in both housings. Also check to see if there is a Pressure Relief Valve (poppet valve) installed in the engine block. This would be located on the lower starboard side of the engine near the exhaust adapter and powerhead (engine block) interface. There should be a round cover plate (removable) that is fastened to the block. The poppet is located under the plate. Check the condition of this valve. These can cause temperature-related issues as well.

[Bottomline]

Thanks for the reply.

I'll check that popet also.

Nice boat you got there!
John

[northeastcat]

I have been having an over heat problem on the gauge and I found my mota had no t stats too. After inspecting the poppet valve I found multiple rips in the diaphragm. Check your diaphragm closely. Change it if any suspicions, and put t stats back in.I got a feeling you are seeing the same thing I was and some wizard previous to us removed the t stats trying to stop the run hot condition. I have not been able to try mine out yet with the improvements, Hopefully it does the trick. NE Cat