hi all....had the s2 put back on the road today with a brand new mot and tax. i took it out for a drive and after a while of driving it sounded a bit "boggy", lack of power, popping and banging wen slowing down/lifting off.
I pulled over and could hear like bubbling from the thermostat housing so unscrewed the coolant filler cap on the bottle a bit and loads of pressure was being released and carried on hissing out of the cap for like 10 mins. i also noticed the exhaust manifold was glowing where it was so hot.
the temp gauge was within the normal running temp area and wasnt in the red.

this happened twice but when left for about 2 hours its fine again.
checked thermostat and thats fine to.

anyone got any ideas? cheers