leaking thermostat help

General Boats and Motors
1
A little help please. Mercury 40 HP two-stroke. 2001 year motor.

I think I have a leaking thermostat (or diaphragm). The throttle was stuck the other day and I thought it was the control cable. But once the cable was disconnected, it moved fine and the throttle mechanism was frozen. Behind the mechanism and inline with the main bolt was a washer (sort of a drag mechanism) and it was all rusted. While fooling with this and revving the engine high, water squirted out of a hole in the thermostat housing. This of course surprised me as I did not expect to see water coming out of the powerhead where it would get things salty and wet under the cowl.

You can see the hole in the center of the photo below, between the bottom two bolts on the thermostat housing. The exploded view drawing of these parts is also in a photo below. I think maybe the diaphragm is broken and letting water leak out. Any thoughts and anyone else experience this before? Diaphragm is part #18.

The working theory now is this diaphragm has been leaking for a while and thus the rusty throttle washer.

Drawing

Photo of thermostat housing

Thanks

2

Most likely a bad poppet valve, good idea to replace thermostat at same time, fairly inexpensive parts and pretty simple to do.

Russ B. Formerly known here as “Top2Bottom1”
www.joinrfa.org
God is great, Beer is good, People are crazy

3

Thanks RussB. I figure I will be getting a handful of small parts from the gaskets to the thermostat to the poppet valve, etc. if I took the housing off. Probably replace most of what’s in that housing.

Looking for confirmation that something was up, but I guess it is pretty obvious that if water is coming out something is wrong.