1980-81 Mercury 50 HP - Thermostat?

[Dee Rambin]

Howdy all, new to the board (1st post), but not to the site. I have been reading posts for several weeks that have helped immensely with solving many problems I have had restoring a 1980 Bass Tracker III. I have replace the entire water pump assembly in this motor and started it for the first time last night and there was no water coming from the "tell-tale" pee hole. It was stopped up by dirt, assume to be from some critter, cleaned out hole with soft wire, only to get about a teaspoon of water out. Ran the motor for short periods with both the motor flusher on and in a trash can filled with water - neither seemed to matter. I know the hose to the tell tale is clear, up to the fitting on the motor. I am also sure that the tube from the water pump to the engine was lined up correctly when the lower unit was installed. The key was installed correctly in the pump, and the drive shaft was turned clockwise when installing the pump cover.<br /><br />My question is whether this motor has a thermostat or not? It is a 1980 or 81 model, 50 HP Mercury, SN# 5799294. I have read my Clymers manual cover to cover and cannot find mention of a thermostat (except for V6, and how to test).<br /><br />I only ran the motor for very short periods - a minute or two each time letting it cool between, afraid of it overheating since this is the first time it has been run in 5-6 years. If not the thermostat, any ideas on where to look next?

 

[ODDD1]

Re: 1980-81 Mercury 50 HP - Thermostat?

Deek, no thermostat....plugged telltale a common problem....to tell if it is pumping, startit up in the bucket,make sure the water covers the whole lower unit, plus a couple of inches....the flat cover [exhaust cover] on the left side of the engine is the first place the water goes, and it should stay the same temp as the water...if it gets too hot to touch, you are not pumping water...

 

[tmcalavy]

Re: 1980-81 Mercury 50 HP - Thermostat?

Yep, no thermostat(s). I've got a 73 Merc 500 50 hp inline 4cylinder that does the same thing. You have to give it a little juice (throttle) to make the water pump get up to speed and start throwing water out the tell tale. Once you get it going it will put out a good stream, if everything is kosher with the pump.