Just need to check where the coolant goes within the engine, apart from the radiator cap, facing windscreen, to the right of the radiator cap in the corner is a cap with 'coolant/refrigfrant' is this the engine coolant or air conditioning coolant?

 

Cheers Ed

ye thats the coolant got a serrated dipstick for the level

Is that engine coolant then?

ye its the engine coolant ie antifreeze 33% the air con is a pressurised system all on its own

Clever idea, but how does it work, as the cap doesn’t appear to be specified to the high pressure that you would expect in the cooling system?

its an expansion tank, so not under high pressure - the way i understand it, when the engine gets hotter and the coolant expands, it passes out into the expansion tank, and can then be drawn back from it when the level gets low

 

 

im sure someone can explain it alot better than that though!!!

Clever idea, but how does it work, as the cap doesn’t appear to be specified to the high pressure that you would expect in the cooling system?

it is,nt pressurised in the top up bottle,after you park the car and the system cools down if your rad needs a drink it syphons of the bottle back up the small pipe and under your rad cap, its called a "pressurised system" allso with it being that type of system water boils at a higher temp than 100 degree