After topping up my coolant a few months ago, and going for a drive, I got a phonecall from my housemate who'd found my expansion tank cap on the driveway (I'm guessing I was having a special day and didn't put it back)

Anyway, being the nice chap he is, he put it in his room for safe keeping. Upon my arrival, being the slightly disorganised person he is, he'd lost it. So, of we trot to scrappy to get a new one, and being no 300's, I grabbed a 440 one, along with a non leaky oil cap.

Grand, work our way to yesterday, when housemate found my radiator cap. I was dubious about them being the same pressure rating, and yup, upon checking, the 440 one is 150kPa where as the 340 one is only 75kPa.

Worth noting incase anyone else has done what I did, I'm not sure what in the cooling chain would only be rated at 75, but I'm guessing not worth taking the risk!

I dont know mate but i have an S70 one on mine, havent checked the rating, afaik thats the blow off pressure if something was to go wrong?
Adam

Yeah, agreed it's the blow off, and should never get there, but the 440 one is double the spec so if something did go wrong !

it would either burst a hose off or blow the shit out of your radiator