Over ride switch is masking a problem.
Standard fan, radiator and switching set up is more than enough with a car in standard guise or even slightly modded.
I have 2 years competing in GTA's at Hillclimbs, Sprints and Track days with the standard set up in good working condition with Zero problems.
1. Most important because of the radiator design, is to make sure none of the magic red water/ silt has built up in the lower parts of the radiator side panels, lowering the cooling capacity. Have the radiator stripped to inspect, prob best to recore at this stage.
2. Check all earthing points on the car.
3. Ensure fan is the correct type and is working smoothly and quietly.
4. The fan/bumper cowling must be fitted. (more important than you think)
5. Test and inspect all wiring.
6. Fit a new fan switch, not expensive.
7. Ensure the correct GTA/Renault/Alpine only thermostat is fitted (very important)
8. When bleeding check that the radiator bleed tube is not full of the crud from our lovely red water.
9. Ensure head gaskets are not on there way out and causing higher that normal temps in the engine as this is where the temp is read from and not the radiator.
Do all this and your water system will be fine is standard condition, miss any bits out and............. well thats up to you.
No charge for my info.
