Radiator Spare Tank

[ozone]

My radiator seems to have a lot of pressure. This has caused some hose to burst which I replaced - this is the one with a few outlets and cost RM 300 plus. Then the radiator spare tank joint broke which I changed.Then the radiator joint broke.All this is due to high pressure which you can feel when you press the hoses after the engine has been running for a while.What can cause the extremely high pressure ?1. Gasket blown2. Cyclinder head crack.I don't think it is either as the car would have overheated and the radiator water is clear.Is it possibe that this is due to faulty radiator spare tank cap ?If yes, how do I know it is faulty ?Any idead how much the cap cost ?Also, the cap that I have is for 200 whatever ( see on the inside of a cap )Is this the correct cap for E36 325 ?What is the significance of this figure - is there a valve in the cap to release pressure once it reaches a certain pressure ?Would appreciate of anyone who knows what's happening can advise.My car has been towed 3 time in the past 3 weeks (once in Batu Pahat, once in JB and last week in Ipoh)Thanks.