Overheating Vectra?

[Jackson74]

Just bought a cheap runabout '98 1.6 vectra. Car fine on motorways but when hit town, the car temperature gauge says it is overheating. Engine does feel very hot. I changed the radiator fan which had blown and it now works fine, but went to Northampton, fine, until hit town centre and started to overheat again, same thing. I've even put the fan on constant on start-up but still overheats. Has anyone any ideas as this one has stumped me?

[scrappylane]

if the fan runs constant then theres only two things that will stop it cooling the water.1st is the waters not circulating round the system,ie,the thermostat is stuck shut.2nd is exhaust gasses getting in to the system,ie,head gasket.its not the water pump as its run off the cam belt so its spinning and its not leaking,could be a bad air lock,try bleeding the system

[Jackson74]

Thanks scrappylane! I bled the cooling system and checked for airlocks, still overheats. You have come up with the same things me and a few others suspect is wrong. Thermostat or the dreaded head gasket. I'll try the thermostat this week. Is there a test for exhaust gasses in system, as there is no sludge in oil or on oil cap, no water or oil coming from exhaust system, but does smoke a bit when started, but nothing too noticeable.

[TWR]

Hi, have you checked the rad cooling Switch? Flush out the Rad, then re-connect, when the engine is up to the right temp check ALL the hoses including the heater hose they should all be hot, the system can be pressure tested it does not cost a lot, Myself I do not think it's the Head Gasket, You say when on motorway the Engine is OK, In town problems, That should tell you, Has someone restricted the air flow to the rad by putting a cover on the inside of the Grill?