ZR expansion tank water boiling

Hi All,



I’m having overheating problems with my ZR 160. It started a little while ago where after 30 mins of so of driving I could hear the water in the expansion tank boiling.Once it had cooled down I disconnected the sensor that activates the fan (meaning the fan now runs whenever the car is started), put the heater on (which blows hot air) and drove home.I thought perhaps the thermostat was faulty and swapped this out for a new one (also checked that the new one wasn’t a dud before fitting) and bled the systems using the bleed screw on top of the metal pipe below the air box.



The water in the expansion tank is continuing to boil up and I’ve noticed that if I reconnect the fan and then take it for a drive, the fan will not kick in. There’s no obvious water leak, the water is running clear and the oil is as it should be so doesn’t look to be a head gasket.Also if I disconnect the radiator top hose while the engine is running, water is being pushed through so it doesn’t look like the water pump either…



It’s doing my head in, does anyone have any idea what could be causing it?



Thanks in advance.

from the last news http://ift.tt/1u01ExB

via IFTTT