what temperature is too hot

[lfg]

175 optimax 1b244369
in other words at what temperature does the solid beep alarm sound off. This when just running a little above idle (in example in the 5mph no wake zone.) and before the poppet opens up

[lfg]

and speaking of the poppet valve is it just a fully closed, fully open valve or does it open and close gradually?

[EuropeanAM]

Question-1: The varies from one calibration to another, but normally if you get into the mid 160's it's sounding. Normally temp is going to remain within 15 degrees of thermostat setpoint temp.

Quesiton-2: It's a pressure operated valve. Though it's progressive, the RPM's at which that "progression" occurs are usually a range in which you don't run the engine. In some cases, with a brand-new/fresh water pump, you might see it "cycle" pressure at around 900-1100 RPM's (that's simply the poppet opening and closing). Don't think much of it... it just does it's thing in the background.