Toyota MR2 pinking and starting to overheat

If no obvious water leaks and fan cutting in o.k ,few possible causes , timing belt jumped , water pump ,head gasket . Could try bleeding again and see if any air in system .Might be advised to do the usual pressure test and block test on cooling system and see what shows .

Hi I recently fitted a new radiator and thermostat to my MR2. I refilled the coolant as Toyota say, bleeding it from the heater and radiator bleed points. I used 50:50 blue antifreeze mix.

I drove two steady 30 mile motorway and heavy traffic journeys straight after and all was well apart from a slight gurgling when I put the heater on. When the engine was cold I checked the coolant level and it had dropped by about half a litre so I topped it up.

The next day I was driving it a bit harder and it was pinking under load between 2000-4000 rpm. I drove it again that evening and once it had warmed up the pinking returned. Only a 5 mile journey but I spotted the temp gauge rising. I left it ticking over with the engine fan on to see if it would cool down but the temp continued to rise slowly until almost 3/4 of the way to HOT so I switched it off.

Then I could hear the coolant bubbling and hissing in the engine bay.

I looked around the car for leaks and it was ok apart from some water at the back of the engine bay - I think this is where the expansion tank breather vents from its pipe.

Any thoughts?

Thanks

check the expansion cap as well,the head gasket could be gone,have you checked the thermostat is not sticking,might be worth disconnecting hoses and flushing through with water to make sure there are no blockages

it probably still has air in system these are a pig to bleed properly