Re: Poppet Valve 83 150 Black Max
The poppet valve is actually a 'pressure relief' valve.
At idle the thermostats control water flow thru the block, maintaining tempreture. As engine speed and water pressure rises, the thermostats are unable to flow enough water to maintain cooling, this is where the poppet valve begins to open, it the factory spring pressure, increasing water flow thru the motor.
Check the popeet valve seat to be sure that it is not sliding out of the block as the poppet begins to open.
Pull your T-stats and test for full opening opening in the range 140 - 145, repalce if needed.
Check impeller vanes for wear, replace if more than 2 years old. While you are looking at the water pump, check the stainless wear plate (lower) and cup (upper) for wear 'rings' worn into them from the center sealing lines on the top and bottom sides of the impeller. If the 'rings' worn into the stainless are deep enough to 'catch' your fingernail into then it is time to replace them, the pump is loosing a larger percentage of its low speed pressure and flow from in adequate sealing at these surfaces.
