Lude Generation

as titled, for Will's silver 4g which has a coolant leak from somewhere and understandably started overheating the other day according to temp gauge during convoy to JF, but then showed stone cold on temp gauge towards the end and the way back home too

dodgy sensor? or another possibility?
cheers

Could the thermostat be stuck open?

I'm not sure, but I think that if there is not enough coolant in the system to reach and subsequently heat the sensor, it would read cold.. I'm probably wrong though.

I think to answer the question of wehther the sensor is bad or not is to feel the temperature of the air - if it is hot but the dial says cold, then its a bad sensor.. if the air is cold and the dial says cold, it's either a stuck open thermostat (as said above) or there is no coolant left.

As Merlin said thermostat or a dodgy sensor. Both pretty cheap and worth changing for maintenance anyway bud.

surely if the thermo was open or not enough coolant, wouldn't it read too hot?
if not, then ill get that thermo changed first, easy swap

ill look up the location of the temp sensor now

If the thermostat is open it takes longer for the coolant to get up to temperature. If there is no coolant at all, then what would the sensor read? I don't know if hot air would be enough to make the sensor send a signal to the temp gauge..

I'm probably not helping with my guess-work. Sorry.

ah! is the temperature sensor that you see read on the dash the temp of the coolant? or inside the engine block?

don't worry bb1boy, any help or suggestions to me is good help

*edit, is this the temp sensor in question (ok this is a B series, but is it the same location?)

It is in roughly the same location. Gearbox side near the front of the head. The gauge has its own separate sensor, ECT gauge sending unit in the diagram above.

When I had low coolant it gave me a hot reading.

Yep, green plug under the dizzy.

brill thank you!