I have finally resolved my over heating problems. I installed a Davies Craig electric water pump (EWP80) in tandem with the MonteCarlo mechanical coolant pump.
I drilled two 5mm holes in the in-head thermostat to enable the EWP80 to run even when the thermostat is closed.
I installed the EWP in the radiator return pipework by the radiator. The pump is orientated such that air cannot be trapped near the pump gland.
I have replaced the cylinder head over temperature switch with the Davies Craig temperature sensor putting the sensor right at the top of the cylinder head.
I fitted the pump controller in the centre console in front of the gear lever.
I am currently using a target coolant temperature of 85C. At 65C the pump runs for 10 seconds at 6 volts and then lies dormant for 10 seconds. At 80C the pump runs at 6 volts and increases linearly to 12 volts at 85C.
The coolant temperature now remains between 75C and 78C. The oil temperature is very similar.
I have also applied Zircotec's ZircoFlex sheet to chassis tubes and the coolant pump inlet pipework to stop the exhaust manifold heating the coolant.
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