It was a very hot day in Sydney yesterday and whilst my MIni did not overheat it was getting very hot. Normally it will get quite warm if stuck in traffic with the temp rising upto about 95 degrees but then returning to normal at about 75-80 degrees once on the move. Yesterday however once it got over 90 degrees it would not come back no matter what speed I was going. Then this morning (which is quite cool) while driving it was nice and cool at about 70-75 degrees but as soon as I stopped at the lights I could watch the gauge rise quickly up to about 90 degrees. Much quicker than it used to. I have checked the coolant level which is fine and i'm not losing any. The radiator was new not long ago so should also be in good condition and the heater matrix is brand new. I have not changed anything with regard to timing or mixtures either.

Could it be a failing water pump? Any ideas would be appreciated.

I'm having similar problems with my mini. Seems to be using alot of water. The radiator has been cleaned, new radiator cap flushed out and replaced with new coolant, replaced the thermostat, all the radiator hoses. Took the heater box out, but because it's Auto I'm putting in back in. We purchased a new water temp gauge, but is there any other gauges or sensors within the engine bay (silly question I kno) but haven't had the car that long, and just had it re-registered. Maybe the water pump it self is on the way out.

Mines not using any water and used to cool down once on the move. Even turning the heater on does nothing.

oh ok, I might have the radiator checked out again. And replace the water pump.

Where are you loosing the water? Is it coming out of the overflow through the cap after you stop or are you losing it somewhere else?

Loosing it else-where. When I pull up to park, it just drains out. Possibly the radiator needs to be replaced?

Hi apart from the obvious check for leaks etc have you checked in the rocker cover ?
Does it look normal or do things appear brownish/creamy ? if the latter, you may have a blown cylinder head gasket. The water gets forced into the oil galleries.
Similarly, is the coolant contaminated with any oil ?
I hope it's not any of this but worth a check

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'98 Mpi Sportspack + 7 port alloy head

Have you got the right radiator cap? If the wrong one then there is not enough pressure on the cap to the radiator and therefor it will overheat and leak out of the overflow pipe.

Tried flushing your radiators??

I drove Lillee yesterday and on really hot 40 degree days and she does heat up but when driving along she cools down quite well. On hot days the gauge stays at half nearly all the time. So long as it is not overheating it should be fine.

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Lillee - 1969 Morris Mini K

Thanks for the info. The coolant is alryt, same with the oil. Might have to investigate about the cylinder head gasket, same with the radiator cap. I have a spare radiator with a new core. Might change it over with the new water pump and radiator cap.

Well it hasn't overheated yet but the temp seems to rise very quickly as soon as the car is stopped at a set of lights. Its rising quicker and higher than I have noticed in the past which is why I thought maybe the pump is on the way out.

Anyone had a water pump go? What are the symtoms to one on the way out?

The two main reasons cars overheat (above the normal range is overheating) is because there is not enough air going through the radiator or there is not enough water circulating.

A loose fan belt will let the fan turn less efficiently, similarly a build up of sludge in the radiator means less water circulating to control heat exchange.

A water pump has a couple of signs that it is on the way out. Traces of coolant seeping around bolt holes or past the seal. The bearing begins to seize and its hard to turn (loosen the fan belt and turn it by hand to see). Also the impellers corrode and simply cavitate the coolant rather than push it around the motor.

A water pump is relatively inexpensive (less than $50). A new radiator about $220, a radiator rebuild is about the same price. Engine coolant flushing soultion (to flush out the sludge in an engine) is about $10. A thermostat is about $20.

Minis dont have a lot of cooling ability so its important that all of the above is working efficiently.

Thanks Mike. Will try flushing the system and double check the thermostat first. Then look at changing the water pump second. Cheers.