Jaguar Repair: them, correct speed, thermostat

Question
why can't I run without a thermostat, I have done it in other models that tend to run hot and it has always worked well

Answer
Hi Kelly,
If you look closely you will notice that there is a large bypass hose on the thermostat housing and look at the thermostat itself and note that there is a large flat valve on the end of the thermostat. First, if you leave that large bypass open (no thermostat) a good portion of the coolant will not go to the radiator but will return to the engine and cause over heating. Second is that the size of the opening in the thermostat when it is completely open restricts the speed of the coolant flow so as to pick up more heat from the metal and to allow the coolant to have the correct speed in the radiator so as to transmit more of the heat to the air going through the radiator. Many race engine builders put a blank plate in place of a thermostat to control. The old method was to just knock the guts out of a thermostat and use that as their blank plate.
Howard