Radiator caps

[Sloppy 2000]

I have a MK1 2000 with a normal bottle on it. At some point the radiator has been changed to one with horns on. Not the usual squared off one.

Just lately it has ben boiling a bit and blowing off water. What I need to know is whether there is any reason, that the radiator cap, for this radiator needs to be a more than the 7lb that is on it. It has only recently started to play up. I have a 13lb (which I have not fitted) and a new 7lb which I probably will.. and just hoping it is something that one of you knows something about.
Just for interest why are there 2 different strength caps?

If not, will have to look elsewhere for the problem. Which would be a shame!!

Jeffrey

[Alec]

hello Jeffrey,

a higher cap pressure allows a system to run hotter which is more efficient but the temperature at which an engine runs is controlled by the thermostat.

If it is overheating there must be a problem, and most common I would say is a blocked radiator? A high pressure cap only delays the point at which it blows.

Alec

[Charles H]

Mk1 cars have smaller head studs and are therefore only able to be torqued down to a lesser degree than later engines with larger studs. Therefore the Mk1 must use the 7lb cap or you risk blowing the head gasket.

[Sloppy 2000]

Thanks Every one. Thanks Charles. I would not want to blow the engine.!!