How does the T-stat Pressure Valve work

[Hvymtl]

I have replaced them but don't understand what they actually do since they don't appear to block anything? The T-Stat controls the water to the heads

 

[classiccat]

Re: How does the T-stat Pressure Valve work

They bypass the thermostat at high-speed....as the water pump is generating high-pressure in the cooling circuit.

 

[rscotth]

Re: How does the T-stat Pressure Valve work

The pressure valves or poppet valves also control water flow but do so from pressure instead of temperature. In the picture you can see the springs will be going into the power head and hold constant pressure on the poppets and they seat into the rubber grommet. When you get into the higher rpm's like at plane speed the water pressure pushes these open and floods the power head.

 

[schematic]

Re: How does the T-stat Pressure Valve work

When you get into the higher rpm's like at plane speed the water pressure pushes these open and floods the power head.

View attachment 199777

Close but backwards. The springs aren't in the powerhead. They are in the adapter plate which is where the water escapes. The power head is always flooded, but flow is limited by the thermostats and poppet valves.

 

[rscotth]

Re: How does the T-stat Pressure Valve work

10-4 your absolutely correct! Page 781 of the factory service manual has a great water flow diagram for the V4. Sorry for any confusion on my part.

RSH