Radiator fan!

Hello all! I have an MGF MK1 1999, currently got issue with the radiator fan not coming on. I have changed the relay, fuse, radiator, radiator fan, coolant sensor, coolant gauge and coolant cap. But no luck. The fan isn’t seized and comes on when unplugging the coolant temp sensor. Do you know what could be causing this issue? 

First question, can you describe situation in which you expected for radiator fan to come on?
Second question, you car is not VVC model?

Hello, the radiator fan doesn’t kick in to cool the car/ coolant. If ran for long enough it will boil the coolant and blow from the coolant cap along with the coolant gauge shooting up. But no sign of the fan ever coming on. This is either when driving the car for 20 mins or so or leaving the car to idle for over a hour. This is on a 1.8 118bhp non VVC car.

You do not have aircon inmyour car, do you?

If you do not have aircon in your car, and you chanhed all items from list above, and testing with unplugging cts is working, my first suspect ismfaulty new temperature sensor.
Had a situation when garage odered new cts and 2 new were faulty as well as original from the car. They found out aboit that when they removed one from car which was proven to be working.
On the market there are faulty new temperature sensors.
 

Okay thanks! I’ve got a spare used one that I’ve picked up from an old part. I will give this a go! Do you know any other way of testing the sensor? Would putting it in hot water trick the sensor to turn on the fan?

Putting the sensor in hot water might trigger it, but if sensor is faulty fan will not be triggered. In the same time how you will measure how hot is the water?

Withoit aircon, fan should be triggered at 102 degrees Celsius and switched of at 96.

Might give this a go! Would just use boiled water from a kettle. As I believe this should be as hot as the coolant when the fan is needed to be on?

Water boils at 100 degrees (slight difference if you live on higher altitudes) and when boiling temperature in kattle is reached temperature will not rise no matter how much you try to heat it more. If sensor is within tolerance you might not ever reach temperature at which fan will be triggered. 

Tell me did this happened after you changed coolant, as you might have air in the system? To get the air out you need to bleed the system from all 3 points. See here:  https://www.the-t-bar.com/forum/roverlike-s-guides/99221-3-points-coolant-bleed-procedure
 

This has happened since I’ve had the car unfortunately! But I’ve bled the coolant multiple times but never reached the point of the fan coming on.

Have you used 3 point bleed procedure as described above? It is important to bleed it that way.

Adding salt to water does increase the boiling point.  A 10% salt solution will boil at 102c...