had a long run into London last week took 3 hrs...used the air con a fair bit and the heater not that it got hot...it blew a lot of cold air even when set to 40....when i parked up the car boiled over from down by the expansion resevior bottle...i topped the car up with coolant and water a few hours later and ran back home no problem...but didnt use the heating/air con that time....do you think its connected or was it an air lock or dodgy rad cap?

i having exact same prob here bro

Ive recently had the same problem, try doing a total fill up. Take off rad cap and screw, run the engine and keep filling it up til full. Do a search and somebody will give it in more detail.

Does it smell of burning antifreeze on the outside, heater matrix hoses are going left right and centre at the mo, just done mine and all is now well.

Could be your Heater Matrix ? Sounds to me like your Culprit.

having the aircon on has a very strong influence on the coolant temperature.

This because the AC condensor in front of the radiator gets extremely hot.

 

If your cooling system is not working 100% it can cause severe overheating problems when driving around in heavy stop-go traffic.

This is especially the case for automatics, since the radiator has to cool the AT box as well...(and the AT box also gets hotter then normal in stop/go traffic)

 

I found this useful checklist/guide last week regarding cooling problems:

http://members.optusnet.com.au/markfield/overheating.html

 

-Eric

ok my boiling up prob is related to an air-lock which got in the matrix...thus causing the cold air no matter how high the setting....as the coolant soaked up the heat the air bubble got compressed to the point it burst forth into the expansion bottle when i parked up....anyway careful refilling when parking the car on a upwards facing slope got rid and now i have lots of lovely heat from the matrix and no boil overs...thanks for the link Eric great stuff on there..should be in the FAQ's that one if not already

Nice one glad you have your probs sorted...