Morris Minor Owners Club

If the coolant keeps needing topping up and there is no sign of a leak or water under the car where has it gone?
Mike

Head gasket failure.

Evening all.
It depends how full you are filling the radiator. It might not be leaking anywhere. When looking down inside the radiator filler, you only need to have the top of the radiator core covered by about 1/2" or so of water. If you fill the radiator to the brim and then put the cap back on, the water will expand when the engine gets hot and the surplus will vent down the overflow pipe and away. Then when everything cools down and contracts, the water level will drop and it will look as though there's been a leak. I check the water level by taking the cap off and poking my finger in the radiator - when cold of course - until it rests on top of the core. If the water wets my finger as far as the first finger joint, that will be fine. All that free space above is for the water to expand in to.
Hope this helps, Colin.

Fit a simple catch bottle on the overflow pipe - then the rad will suck back any water that overflows when it cools. And as above - don't overfill.....

Hi all
Unless a recovery cap is fitted to the radiator, it will not suck up the overflow from a catch tank. Recovery caps can only be fitted to short filler necks. They are not made for tall filler necks.
Cheers Bob

As far as I know - all caps have a 'vacuum breaker' arrangement.....

Hi all
Using a non recovery cap will allow release of coolant but only return of air to the system, not water. See link.
Cheers Bob
http://www.tridon.com.au/products/Trido ... iator-caps

As to the original question, over what period of time does the "loss" of coolant occur? It is possible to have a very small leak that loses water at a rate that is immediately evaporated by a hot engine and that occurs only when the engine is hot, so when you look later, you can't see it. Try looking when the engine is running - but be careful of the fan, don't get fingers, hair, clothes, or whatever, caught.

Head gasket is still a possibility, as is a cracked head; but are there any other symptoms, or is it just a loss of coolant?

Thank you for suggestions. Following your ideas I will investigate further.
Cheers,
Mike