Running hot

[StuK]

Hi all

Took mine out for ashort drive yesterday, probably for the first time in 3-4weeks and noticed after about half an hour that the temperature was in the red zone. So I put the heaters on full blast and returned to base, slowly! The fan took a few minutes to kick in after I'd turned everything off, which surprised me, I thought it would be instantaneous.

Anyway, after leaving everything to cool down I opened the hood - coolant levels were still OK, which leads me to suspect the water pump is not working properly. Does that sound right? Could it be anything else? How could I test it? Also, should the fan kick in straight away?

Thanks

 

[Mike_Pollock]

Could be stuck thermostat, not allowing flow to the rad.

 

[jonk]

Possibly thermostat...? Not too difficult, but a messy job.

 

[robwright]

If the fans have kicked in there is water getting to the radiator as the thermostatic switch is on the radiator. Run the car at idle on your drive until it gets up to temperature. Check that the radiator bottom pipe from the pump and thermostat remains cold until the thermostat opens. Check for operation of the fans. They should kick in before the top mark on the gauge, below the red line. My first thoughts would be thermo switch on the radiator or the fan relay. It is quite normal for the fans to remain on for 30 or so seconds after the engine has been switched. Especially after driving in heavy traffic.

 

[OLD_ian]

When mine was running hot it was the wrong thermostat had been installed. Later the garage noticed that the polarity of the fan motor was wrong as someone had messed up the wiring. This caused the fan to run in reverse sucking hot air from the engine through the rad instead of cooler outside air.

Ian

 

[pauljmcnulty]

The fan took a few minutes to kick in after I'd turned everything off, which surprised me, I thought it would be instantaneous.

The fan should come on when the coolant gets hot. It should stay on after you shut the car off, for a few minutes. Coming on some time after you've shut a hot engine down sounds very wrong!

 

[Mike_Pollock]

My guess -
As the fan took so long to come ON after you stopped, there must be a blockage in the system - probably the thermostst.
If it was the pump you would still get a certain amount of flow caused by the temp differentials, the thermostat would open as it is close to the block and the fan would cut in, as it is, it is just turning on due to conduction through the coolant.
I'd check the bleed valve when its cold, as if there is a blockage it can cause loss of coolant that doesn't show up in the header tank, due to vapour locks.

 

[Buddy]

I agree with Mike's analysis, but also check for signs of leakage around the pump bearing to save having to do that before long.

If a pump bearing fails so does the seal and so loses coolant under pressure then sucks air as it cools, as Mike says airlocks then in the engine so may not show in the levels.