Happy New Year to one and all!

Cobber, thanks for engaging in this. I get what it’s for when it is a small hole in the thermostat.
The floating valve giggle system located at the engine close to the thermostat is intended to pass any entrained air to the expansion tank. The ball then floats in the coolant before sealing with minimal flow (if any) passing through it.
In the pre PRT cars there is another in the “up and over” hose at the other end of the engine. In the PRT cars there is no “up and over” hose it is not required and uses a 4-way “T” piece.  In that case water has an unlimited flow path to the expansion tank unless something else is included instead. 
If there is something to include what is it please?
Is that restriction needed or is free flow vital .
It would be very helpful if someone with a factory fitted PRT could report if there is a small steady flow across the tank from that small hose to the expansion tank once up to temperature from the 4-way T.

Read More...