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Motor Height Question

N

N8te

New member
Afternoon!

I have a 20 Ft Pontoon with a 90 Hp Mercury EPLTO. Motor runs great, the only issue I am having is a constant beep only at Wide Open Throttle. The motor is not overheating(Pees very strong, and the Power head is average temp and able to touch by hand even after running for a while). As soon as I throttle down a bit the constant tone goes off and wont come on at all unless I go WOT. From what I have researched, the constant alarm is for overheating, or possibly over revving.

I am wondering if I need to lower the motor an inch or so. Maybe its loosing traction or losing water flow at high RPMs. Thoughts on possibilities? Its a flat transom with no set back on the motor. I believe that does affect the answer to how low in the water it should be due to water displacement from the transom. (I tried to upload some photos but it will not let me for some reason. But the Cav plate is pretty much even with the bottom of the motor pod)
 
The pee comes off the exhaust manifold on the Port side of the engine....look on that side of the engine at the large pretty square flat plate and notice a fitting and hose attached....that's your pee tube.

If the engine is running it is creating hot exhaust that has to be cooled, regardless of the speed and there is a separate water channel for doing this....the block cooling is a different loop. Soooo your Pop-off valve isn't oppening at about 2500 RPM like its supposed to.

On the rear of the block there is a plate....the block water jacket cover (the spark plugs fit through it), and in the upper left corner is a scabbed on casting with a larger diameter upper part and smaller lower part.....Pop-off is under the large one and thermostat under the lower one.
 
I did lower the motor a few inches, BUT I also ordered a Poppet Valve assembly and a Thermostat kit as well. Going to get those swapped out this week. The Poppet Valve essentially fell out when I unbolted the cover plate, and had some salt corrosion on it as well. Could have definitely been the issue as it may be worn out. Thanks!
 
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