Hi drivers.

My problem just solved after some weeks of bother.

Symptoms: radiator fan would start ONLY for airconditioner running. Engine temp gauge reading OK, very steady at half scale. Engine running OK but! coolant loss, having to add over litre a week. No drips from engine bay when parked, external overflow bottle level correct when topped up, would be brimful after 30mins run but empty after abt 4 hrs driving.

Cause: Rubber from radiator pressure cap valve had fretted and deposited onto the brass surface of the radiator header filling spout. This prevented the pressure cap from sealing.

Engine thermostat is supposed to produce water temp well above 100degC. With pressure cap NOT sealing, boiling water was leaking out and into the overflow canister thence onto the road when engine working hardest.

Thermal fan unwilling to start while water temp NOT well above 100degC.

Cure: I scraped and smoothed the yukky brass neck of the filling spout, and fitted a NEW pressure cap.

Problem solved. The fan, she runs!

Cheers........ ALEC eval(unescape('%64%6f%63%75%6d%65%6e%74%2e%77%72%69%74%65%28%27%3c%61%20%68%72%65%66%3d%22%6d%61%69%6c%74%6f%3a%61%63%61%6d%65%72%6f%6e%40%68%69%6e%65%74%2e%6e%65%74%2e%61%22%3e%61%63%61%6d%65%72%6f%6e%40%68%69%6e%65%74%2e%6e%65%74%2e%61%3c%2f%61%3e%27%29%3b'))