hello , ive just had me cambelt and water pump done about a week ago and since ive had it back they has been a hum that i aint heard before and the water can never seems to be presurized even after a long period of engine running time . is this normal ? i can litreally take the cap off and nothing spills even after long running and whilst running ?? i think they could be an air lock but i just want to be sure before i take it back becuase ive already had troulbe with the garage . the heating works and is hot but im sure it used to get hotter ..pleeease help !!!!

???

If it is up to normal temperature then yes it should be pressurised.

at a guess....id say it just means the water is at a good temperature, dont quote me on that

I'd only be concerned if it was pressurised when completley cold. If you put liquid in an air tight system, then heat it up, you'd expect some pressure............

Yes it should be pressurised, but nothing should spill when you take the cap off. The level may rise a bit and you may hear the pressure released as the cap is turned, but it shouldn't throw out hot water like the old cap-on-the-radiator cars.

Try running for a bit after reaching working temperature, then when you stop, leave the cap on and squeeze the top radiator hose. If it's firm then you have pressure, if squigy then all is not well.

it should be pressurised but only around 15 - 20 psi ..... when the car is up to temp, put heater of hot open bonnet remove engine cover and all hoses should be warm / hot

thanks guys , and ive found out what the hum was ... EGR valve just if you get any weird hums .