radiator caps

[Sloppy 2000]

Hi,

I have had cooling problems (correct that), my mk1 has had cooling problems. The radiator I have bought looks slightly different. Mine is more square and this is rounder and has slight horns, What I need to know is, How do I choose the radiator cap. Some cars had 7lb and some 13lb caps (i don't know for sure but think this is the case). How will I know which one? Were they stamped anywhere. Currently the one I have is 7lbs
Is the pressure down to the pump or down to the radiator?

Jeff

[Mike Stevens]

Hi Jeff,

The pressure is down to the water heating up and expanding in a sealed system. Having a higher pressure allows a higher coolant boiling point.

As to the correct cap, I have a feeling that it should be 13lbs, but it may be that Mk1 cars use a 7lb and Mk2 13lb, but I am not sure. Hopefully, one of our Mk1 experts will be along to advise!

Cheers,
Mike.

[David Withers]

From distant and unreliable memory of the 1965 Mk 1 that I ran from 1970 to 1975, it was fitted with a 7 lb cap. The Mk 2 had a 13 lb cap. The two caps differ in the shape of the lugs and slots so that only the correct one will fit.

[Dazzer]

Use the 13lb Ive used both on my MK1 didnt overheat with either just gives you a little higher boiling point with the 13lb and they are more common as well.

[Dazzer]

Use the 13lb Ive used both on my MK1 didnt overheat with either just gives you a little higher boiling point with the 13lb and they are more common as well.