Morris Minor Owners Club

Radiator Filler cap of my MM 1000 car - the valve of the Radiator cap is broken ,so it has a open hole - is it cause to heat to engine ? may I use a new cap ? look image[frame][/frame]

If the radiator cap doesn't seal the water will not be pressurised which is what raises the temperature at which it boils.
Is the rubber sealing part on your cap intact?
Don't fill the rad to the brim as there has to be space for the water to expand.
If you do fill it to the top excess water will always be pushed out when the engine heats up, that's the way it's designed.

not a rubber sealing, not seal - and broken valve of the cap in middle ? what must I do ? I have seen when run about 10 Km - water come out in off-low hose - I think that is the problem to heat my car engine very soon - can anyone post a image of the original radiator cap of MM1000 -1957year

All radiator caps for M1000 are the same, 1 inch long spring, 4lbs pressure. If yours is damaged you must replace it.

Sandun - easier, quicker and cheaper to just get a new cap that you know is in good condition. If water is leaking out when you are running the system cannot work properly. As Mike says the type you need is the one he describes.

If it's going to be difficult or take a long time to get a replacement you could cut a disc of rubber that will fit in the filler neck.
You should be able to get an idea of how thick it needs to be from the gap where the old rubber went.
The worst problem you will have will be getting it out but I expect you could tweak it out with a small screw driver, just make it a drop in fit.

ok I am going to buy new one - but what is " lbs" of morris minor 1000 - 1957 year - radiator cap ? LBS. 4 ? or LBS. 15 ? ,LBS 13 ?, LBS 7 ?????

4 is standard.

why the MM 1000 radiator (cooling system ) not a overflow recovery tank - it off-low hose free so, when heat water go out

Its not required in colder climates but you could always fit your own using a washer pump bottle. In theory, when the engine cools, it should syphon the water back into the rad...

Yes - that works IF the new cap has a vacuum-breaker valve. Not all are so fitted.......

Also be careful about the length of cap you order. Someone had fitted a short one to mine which meant water and steam came out from the top. Fortunately I had a long one lying around.

Ah, I knew all that 'worthless junk' would come in handy one day.