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1975 evinrude water flow question

S

schreiberpd

New member
I’m working on a ‘75 Evinrude 9.9. The lower leg is currently off. When I hook a garden hose to the copper water tube, there is no flow.
With the thermostat removed, and water hooked up, I get good flow out the exhaust ports.
What is supposed to happen before the thermostat opens?
Do I have a blockage somewhere or is this normal? TIA.
 
The thermostat traps the water in the block to warm it up and as it does, the thermostat opens and allows the water to flow through the block at the correct operating temperature. I couldn't remember if that model had a telltale or not so I looked your engine up and it appears it did not have one that I could find. I would surmise that there is a small bypass to allow some water to flow until the engine warms up.
 
I also remember, on a 1976 15hp model I had, which is identical to yours except the carb, that one thing I liked about it was that it gave me a good indication of the condition of the impeller when I ran it. The indication was this. When I was cruising down the lake at a fairly constant speed for a while, I could look back and see that the spray of water out the exhaust changed a little bit. This is a little hard to discribe but if you can think of a water spray as a triangular arc, the main flow of that arc seem to move away and then towards the back of the motor, as I assumed the thermostat opened and closed. The spray would kind of swing from more pointing down to pointing up, by a small amount, as that t-stat opened and closed. As the impellar got more used, after about 4 or 5 years or so, that arc changed in a way that the spray wanted to be more down, closer to the motor. To the point that when the t-stat was closed it was almost impossible to see the spray. It kind of had a guy worried that the pump had failed for a minute or so until the t-stat opened more and the spray moved away from just dribbling down the back of the motor, and was now shooting away from the motor in better view. So the range of the arc would change depending on the power of my impeller. That was my indicator that it was getting to be time to change the impellar, since I assumed this observation was due to a loss of power from that impellar due to usage. When I did change the impellar the spray arc resumed its more visable spray whether the t-stat wa opening or closing.

Anyway, that was a story to highlight that water should come out the exhaust port even when the t-stat is fully closed, however, when it is fully closed (never like that when the motor has warmed up) the spray is more of a mist then a spray. Very hard to see but easy to feel if you put your hand back there. When the t-stat opens, about a minute or so after start up depending on the temperature of the water, water should spray out that exhaust hole, whether the t-stat is opening or closing. Again, the t-stat should never fully close when the motor has been warmed up. Only reduce the flow of water, not stop it. You should always be able to see water spraying out that exhaust hole.
 
optsyeagle said:
I also remember, on a 1976 15hp model I had, which is identical to yours except the carb, that one thing I liked about it was that it gave me a good indication of the condition of the impeller when I ran it. The indication was this. When I was cruising down the lake at a fairly constant speed for a while, I could look back and see that the spray of water out the exhaust changed a little bit. This is a little hard to discribe but if you can think of a water spray as a triangular arc, the main flow of that arc seem to move away and then towards the back of the motor, as I assumed the thermostat opened and closed. The spray would kind of swing from more pointing down to pointing up, by a small amount, as that t-stat opened and closed. As the impellar got more used, after about 4 or 5 years or so, that arc changed in a way that the spray wanted to be more down, closer to the motor. To the point that when the t-stat was closed it was almost impossible to see the spray. It kind of had a guy worried that the pump had failed for a minute or so until the t-stat opened more and the spray moved away from just dribbling down the back of the motor, and was now shooting away from the motor in better view. So the range of the arc would change depending on the power of my impeller. That was my indicator that it was getting to be time to change the impellar, since I assumed this observation was due to a loss of power from that impellar due to usage. When I did change the impellar the spray arc resumed its more visable spray whether the t-stat wa opening or closing.

Anyway, that was a story to highlight that water should come out the exhaust port even when the t-stat is fully closed, however, when it is fully closed (never like that when the motor has warmed up) the spray is more of a mist then a spray. Very hard to see but easy to feel if you put your hand back there. When the t-stat opens, about a minute or so after start up depending on the temperature of the water, water should spray out that exhaust hole, whether the t-stat is opening or closing. Again, the t-stat should never fully close when the motor has been warmed up. Only reduce the flow of water, not stop it. You should always be able to see water spraying out that exhaust hole.
Click to expand...
That, my friend,
Was a wonderful description of the nuances of water flow out of the exhaust outlet, I too, was obsessive compulsive about exhaust snout water flow starting with my first 1959 Johnson 18 hp to our new 1976 200 Johnson. Brought back fond memories. Sadly, once I started getting into girls in the summer of '76, I had to leave my old fetish behind! LOL!
 
Thx for the replies. No tell tail on this motor, though I’ll likely put one in before I’m done. I can’t say that I’ve ever paid enough attention to water flow other than to check that I had it. My ‘79 (bought it new when I was 16) has one, and that’s what I’m used to. And it’s a wild spray out the upper exhaust when the thermostat opens.
It sounds like maybe I do have a small blockage somewhere because with the Tstat closed, engine off, there is zero flow. looking at the underside of the power head, I can see where water comes out after the thermostat. Anyone know where water comes out of the head before the Tstat? That’s where I need to start.
 
My first new one was a 1978 25 Evinrude when i was 17, so we're close in age. I'm still thinking there is a bypass in the block or thermostat cover that allows a small amount of water around the thermostat, It may be just plugged with sand. Is your primarily fresh or saltwater use?
 
Have seen a lot of motors with tell tales that overheated.-----Install a new impeller every 5 years and there will be no need to look at a tell tale.
 
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