Hey Guys.

Took my Mini for a quick fang around the city before I got shipped out to Eucla to work on the Checkpoint for a month. I was driving as I normally do, which is quite spirited, and checking the gauges, all seemed fine and dandy with the engine. When I pulled back into the car port, I noticed a fair amount of water coming out the overflow pipe from the radiator. I topped the poor girl up and about 1ltr had vacated the premises.

I didn't have time to have a good look as I still had to pack and get everything ready so I parked her up. I've talked with a couple of people about it and their thoughts were that there was crud in the radiator cap stopping the spring from doing it's thing. Does this sound right? My old man was babbling something about the thermostat possibly not flowing correctly?

Can anyone shed some light on this for me?

Cheers,

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-Wasabi
1972 Clubman - Daily Driver
1962 850 - EW1 Powered

i had the exact same same problem the other night couple of big hills and suddenly my radiator was boiling (with anti boil in it) had stuff in the cap that kept the seal open and she continously overflowed untill i cleaned it now shes all fine

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Enjoy Chris

Yeah cleaning the cap might fix the problem. I've always just put a new cap on, at $6.50 a pop I fit a new cap fairly regularly, part of my major service.

This is a fairly perennial problem with minis. Some blow water and some don't. You especially notice it when you switch the motor off after a hard run without letting the engine idle for a minute or so to let the heat disipate from the cylinder head (and the thermostat is wide open).

The water boils in the head and the increased pressure forces water out.

A mini cooling system is only just adequate when its in new condition and if you have even 10% loss of circulating volume (either by loss of coolant or crud through the system) then you are cooling to have overheating problems.

Now, assuming you do have a coolant system in good shape - the easiest way to fix this is fitting an overflow coolant tank sytem from a Morris 1100, moke, marina or heavens forbid - something from a Jap car. It will stop the mini emptying out its coolant.

From what I have known, those who have their water blown are either or all of the below:
1) have filled their water to the top; 2) have the problem that the spring in the cap lost elasticity so a little pressure will cause the water to let out of the hose; 3) the coolant is not enough or too much; 4) Your raditor have problems.

With regards to 1), I have that experience before when I filled the water full to 100% and everytime it just overflows. You have to make sure it is just right at the "start-of-the-neck" (I think you can see some grille kinda thing there) below the hole (connected to the hose).

You dun really need an overflow tank for an old car (i.e. Mini) though you can, won't hurt.

cheers,
Ben

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1964 Morris Mini 850 - G13b gti powered - classic yet practical
1968 Morris Minimatic - 1100cc - classic & breakable
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