Poppet valve function

[onebadc10]

What is the purpose of the pommet valve .1988 135 merc

 

[gss036]

Re: Poppet valve function

It allows water to circulate through the block and then discharges excess water out the exhaust, thus cooling the engine. If you have a water pressure gauge, you would see a little fluctuation in the water pressure when the poppet opens at about 3000 rpm. The poppet valve is nothing more than a spring loaded diaphragm.

 

[emckelvy]

Re: Poppet valve function

At lower speeds the thermostat restricts water flow thru the cyl block in order to maintain temperature. This is important for idling quality but not so important when running at faster speeds where the motor needs more water for cooling.

Poppet valves open up at higher speeds/water pressure to allow more water to circulate thru the block when needed.

If the poppet doesn't open it could lead to overheating so it's not a bad idea to replace/rebuild them when you replace thermostats.

HTH..........ed