I have a Mk11 cooling system that has been modified to use an EWP and Wards header tank. The system has no thermostat, relying on the pump controller monitoring the radiator top hose temperature to attain running temperature. The controller pulses the pump in the warm up phase which means that there is intermittent coolant flow causing the heater to be hot and then cold when the pump stops. The car takes forever to warm up (especially in the winter when it rarely gets above 75º and never attains full running of the pump). I am considering modifying the system to reinstate the thermostat and have the pump run continuously. However, I want to retain the pump over run and electric fan operation feature from the controller for heat soak when the engine is hot and switched off.
The current pipework has the heater return pipe plumbed directly back into the pump input side and the bypass pipe is blocked off. The original return point for the heater return pipe is also blocked off. I am considering refitting the heater return pipe back into its original position and extending the bypass pipe to the input side of the pump and blocking off the return point for the bypass valve. In other words transposing the heater return pipe and bypass pipe. Thus with the pump running continuously there would be a permanent flow back round the inlet manifold and as the thermostat opens this would then close off the bypass hose and the pump would pull the water through the radiator.
Electrically I propose to put an ignition operated feed onto the pump in parallel with the EWP controller feed thus the pump will run continuously with the ignition on but will also operate via the controller when the engine is switched off. I think I will need a diode in the controller pump feed to prevent damage to the controller from any back feed from the ignition sourced feed.
I am also considering making the ignition feed to the pump 6 volts. As the coolant temperature rises the controller would start to put a constant 6 volt supply to the pump in parallel with the ignition feed. The controller then starts to ramp up the voltage to 12 volts as the target temperature is approached thus overriding the ignition sourced 6 volt feed. This way the controller would have more control of the pump as the target temperature is reached. I believe I read somewhere that Flying Farmer had posted that he had put a constant 6 volt feed on an EWP, if so how was this achieved? I am considering using a MK1 ballast resistor for this. Perhaps the electronic experts among you would know if this resistor is OK for continuous supply to the pump and if the idea of using a diode to prevent back feed into the controller is necessary.
Before I commit to buying the components I would appreciate all thoughts, advise and suggestions.
Dave.
The current pipework has the heater return pipe plumbed directly back into the pump input side and the bypass pipe is blocked off. The original return point for the heater return pipe is also blocked off. I am considering refitting the heater return pipe back into its original position and extending the bypass pipe to the input side of the pump and blocking off the return point for the bypass valve. In other words transposing the heater return pipe and bypass pipe. Thus with the pump running continuously there would be a permanent flow back round the inlet manifold and as the thermostat opens this would then close off the bypass hose and the pump would pull the water through the radiator.
Electrically I propose to put an ignition operated feed onto the pump in parallel with the EWP controller feed thus the pump will run continuously with the ignition on but will also operate via the controller when the engine is switched off. I think I will need a diode in the controller pump feed to prevent damage to the controller from any back feed from the ignition sourced feed.
I am also considering making the ignition feed to the pump 6 volts. As the coolant temperature rises the controller would start to put a constant 6 volt supply to the pump in parallel with the ignition feed. The controller then starts to ramp up the voltage to 12 volts as the target temperature is approached thus overriding the ignition sourced 6 volt feed. This way the controller would have more control of the pump as the target temperature is reached. I believe I read somewhere that Flying Farmer had posted that he had put a constant 6 volt feed on an EWP, if so how was this achieved? I am considering using a MK1 ballast resistor for this. Perhaps the electronic experts among you would know if this resistor is OK for continuous supply to the pump and if the idea of using a diode to prevent back feed into the controller is necessary.
Before I commit to buying the components I would appreciate all thoughts, advise and suggestions.
Dave.
Found them very helpful
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