My car is psychic

[Will Reeve]

Never really thought about it too much before but driving home today the coolant light was flickering, especially over bumps.
Get home, let her cool down, and sure enough the coolant was low (due a small leak from the top radiator hose where the thermo sensor for the fan goes!).
The strange thing is the engine / coolant system doesn't appear to have a level sensor. It's pretty much SD1 I think, metal header/expansion tank, there is a 1/4" spade on the side of the header/expansion tank but nothing connected.

Coolant light comes on with ignition and off when the engine starts.

Coolant light appears to work like it should, on filling the car after the rebuild the light initially went off and then on when it needed more water....as you would expect.

How the hell does it know?

[DaveEFI]

Never really thought about it too much before but driving home today the coolant light was flickering, especially over bumps.
Get home, let her cool down, and sure enough the coolant was low (due a small leak from the top radiator hose where the thermo sensor for the fan goes!).
The strange thing is the engine / coolant system doesn't appear to have a level sensor. It's pretty much SD1 I think, metal header/expansion tank, there is a 1/4" spade on the side of the header/expansion tank but nothing connected.

Coolant light comes on with ignition and off when the engine starts.

Coolant light appears to work like it should, on filling the car after the rebuild the light initially went off and then on when it needed more water....as you would expect.

How the hell does it know?

My VDP EFI has two coolant level sensors - one on the expansion tank and one on the side of the rad. The rad one may not obvious because of the headlight etc wiring and battery getting in the way.

[Will Reeve]

That will be it! I thought I was going mad, I knew there wasn't one on the engine or the heater tank (well at least connected). Never seen one on a radiator before, good idea really. Topped up and the light is firmly off!