HELP Mini One D 1.4 2003 over heating

[mcdowell061]

Hi guys this is my first time posting. I have used this site for help before with other minis, and I know there are some great guys out there who can help.

So I bought a 2003 mini One D 1.4 about 6 months ago. i have driven it for 8000 miles since. then one day I looked it the temperature hand and it was pointing skyward. i pulled over straight away. got the car home.
having read a few forums we thought it was the water pump. so we striped it down took it out. pump was fine but changed it anyway as this is a common fault apparently on these cars. also changed the thermostat and gasket for a new genuine mini one. neither of these where the problem so had to buy a new rad and have it fitted. i also bought a new cap for the expansion bottle as these where know to leak as well.

the new rad worked and the car was running fine for about a month. then a couple of days ago, i heard the fan come on. switched on the heating to see if it was blowing warm air. it wasn’t. so took the car straight home. (only a couple of miles away)

took the car out for a short drive the other day and put the heating on, it was blowing warm air for about 5 mins. not long after the temperature hand hit the half way mark it started blowing cold air again.

iv been talking to a few local mechanics who looked at the car and took it for and drive, none of them think its the head gasket.
the rad has warm water going in but freezing cold coming out as if its blocked or air locked (also i cant find i bleed point, they are suppose to be self bleeding with a pipe from the top of the rad to the expansion bottle) does anyone know where the is a bleed point?

I cant understand why it blows warm air, then when the engine gets up to temperature it starts to blow cold air. I mean I have changed almost every part in the cooling system. There are no leaks either. (no water on ground in morning or anything)

Can any one think of any reason why it would do this or what could be wrong?
This is driving me crazy and I am hiring a car at the moment to go to work so it’s costing me every day it goes on.

Any suggestions welcome

Thank you in advance!

[mab01uk]

Since you have changed most parts in the cooling system......there have been a few cases on here which were hard to solve but turned out to be internally blocked/ silted up heater matrix rad. may be worth checking /removing yours. The petrol Mini's have several bleed valves in their cooling system, so I would have thought the Diesel would also? They are also difficult to bleed and need patience!

It may help to read through this below and some of the links included for petrol Mini cooling problems:
Solving MINI Cooling Problems.......... - Forums

[The Nun]

Check all your hoses, rubber hoses are made up of like 2 layers, it is not unknown for the internal layer to collapse when a hose is hot cutting off or reducing its bore, they can still look ok on the outside when this happens?