Hey guys. Driving home last night my temp shot straight up (125c) after about 5km @ 9pm. Pulled over, popped the bonnet, and the yellow coolant reserve cap had popped off and coolant spewed out of there. I couldnt find any other trace (checked hoses and cap) I lost about 1.5litres.

I left car in ignition so thermo fans would run, got car down to 100c, started up again, then instantly dropped to 89c or so and stayed there the whole way home.


Any ideas as to what would cause my coolant to come out of my reserve tank?