Fiesta overheating

[Mick2122]

I have a Ford Fiesta S reg 98.The problem is it starts to overheat when the temperature gauge is only half way across.The fan does not cut in either. The sender unit for the gauge is ok and I have fitted a new radiator fan relay,could this be a themostat or waterpump problem,also is there a separate switch to to operate the radiator fan

Can anybody help.

[tom hopkins]

not sure where it is but yes there will be a seperate switch for the fan (also check fuses)

[Mick2122]

Thanks for the answers.When the temp gauge gets to halfway or just above the water in the header tank begins to bubble and steam,at this time the top of the radiator is very hot but the base is only warm/hot

[Mick2122]

Thanks mdoo, I'll flush out the rad tomorrow and change the thermostat.Is it possible it could be the water pump?.Let you know how I get on with the rad

[BillyNoMates]

As has been suggested could be a blockage. More likely to be an airlock. When you refill, ensure the heater is turned to maximum heat setting and run up until the engine is warm.

Feel each of the hoses when warm and check the heater output to determine if the water pump has failed. You can also sometimes see water coming from the weep hole in the water pump housing to indicate potential pump problems.

Are you able to remove the connection to the thermostatic fan switch and short it to very the fan is OK ?

[tomtech]

sounds like the water pump is not pushing the water around the system. is the radiator cool while the engine is hot? the rad fan will not start if the rad is cool. the impellor sometimes falls off the water pump spindle, hence no circulation. but of course without having a look its difficult to be sure.

[tomtech]

just to make things worse you could of course have head gasket problems.

[nlr1966]

Feel each of the hoses when warm and check the heater output to determine if the water pump has failed.

"check the heater output to determine if the water pump has failed"

hi - i'm a real no-hoper with cars - can you tell me exactly what htis means and how i check, please. my fiesta is running hot when i go above 50mph, but when i go slower it gradually cools down. i've tried to get rid of an airlock by running engine, but not sure what to do next . thanks in advance for any help.