13 replies to this topic

[Andy91145]

I'm just wondering as I got told by a teacher in college that the only reason a car would overheat if it is stationary is if it has a leak in the cooling system resulting in lack of pressure? As this is my first car and not too experienced with cars I was wondering if it is normal for Minis to do this?


Thanks in advance

[Brams96]

Depends on how long you are stationary. What year & model is your car? Have you checked there is water/coolant in the radiator & the level doesn't drop after using the car?

[Andy91145]

Stationary for about 15 minutes and the temperature gauge goes from the middle to about 3/4's of the way up. Its a 1987 Austin Mini Advantage with a Metro 1.3 in. No the level hasn't dropped and there is no visible signs of a leak i.e on the driveway or on other components where the water has evaporated and left the anti-freeze.

[Brams96]

Next time it happens try turning on your heater on full heat & see if the temp gauge drops. Sitting still in a car without a secondary aux fan and the temperature will creep up. Do you know if the thermostat is working properly?

[Andy91145]

Next time it happens try turning on your heater on full heat & see if the temp gauge drops. Sitting still in a car without a secondary aux fan and the temperature will creep up. Do you know if the thermostat is working properly?

I will give this a shot and it seems to be has no trouble warming up so I'm guessing so.
Thanks for the help

[Brams96]

The engine will warm up to temperature (about 82 degrees) at which time the thermostat opens to let the now hot water go through the radiator to start cooling it to keep your car at it's optimum operating temperature. If the thermostat doesn't open then the engine will just keep getting hotter as the rad isn't cooling anything.
You can check the thermostat by removing it placing it in some water in a pot & heating it up towards boiling. If you've got a thermometer even better as you'l be able to see what temperature it opens at. Once the water reaches 82 degrees you should see the thermostat open.
Or for piece of mind get a new one they're only £3 - £6.

[dklawson]

I'm just wondering as I got told by a teacher in college that the only reason a car would overheat if it is stationary is if it has a leak in the cooling system resulting in lack of pressure? As this is my first car and not too experienced with cars I was wondering if it is normal for Minis to do this?

Hogwash. The pressure does not affect the temperature, it affect the boiling point. Radiators overflow when the boiling point of the coolant is exceeded. Radiator caps are sold in pressure ranges (7 PSI, 13 PSI, even 18 PSI). As you switch to a heavier/higher pressure rating cap you increase the possible pressure in the system and for each PSI increase you raise the boiling point of the coolant by some amount. I can't tell you the exact number... I believe it varies by coolant mix. More info about this can be found in the link below:
http://auto.howstuff...ing-system7.htm

If your overheating problem only shows up when the car is stationary, this implies one of two (or three) things. 1) The water flow at idle is too little (not enough volume) at idle, or 2) Air flow through the radiator is not sufficient at idle. A third possibility is that your water jacket and radiator core are severely plugged in one or more areas and that a complete cooling system flush is needed.

If the problem is a recent development it is not likely to be flow related unless you have a loose fan belt or a water pump with sheet metal impeller blades where a blade has rusted off or similar. If you have taken the water pump and fan off recently for any reason, take a look at the fan blades. The fan will move air regardless of how it is installed but it will move MORE air, particularly at idle, when installed in the correct direction. Look at the tips of the blades. They have a slight airfoil (wing) shape. Note the direction of the blade curvature. The correct fan blade configuration will look like this...

engine ------ ( ------- radiator

[jaydee]

I'm just wondering as I got told by a teacher in college that the only reason a car would overheat if it is stationary is if it has a leak in the cooling system resulting in lack of pressure? As this is my first car and not too experienced with cars I was wondering if it is normal for Minis to do this?


Thanks in advance

Tell the teacher to do the teacher and not the mechanic neither the thermodinamic engineer.

And in most cases the issue is due to the lack of fresh air in the engine bay, thats it.

[pdaykin]

Maybe the teacher was referring to the lack of pressure in the sense that the water had "boiled away".

In which case the engine would overheat.

My Cooper S tends to boil when stationery. As with a lot of older minis it has a mechanical fan so when the revs are low and you are not moving not a lot of air is passing through the radiator.

[bmcecosse]

It should be able to idle till the fuel runs out - even in summer. The 'pressure' thing is just rubbish. Does your Mini have a fan ??

[1984mini25]

Fueling, ignition timing out, fan belt lose, fan on backward or the rad is gunked up can all cause it to overheat.

[Brams96]

It should be able to idle till the fuel runs out - even in summer.

Tell that to all the people stuck in London at the London to Brighton! In theory that may be correct but like so many other things reality is a different thing.

[bmcecosse]

I bet many of them had the grille blanked off with completely unnecessary spot lamps ! Or faulty electric fans........

[JonnyBMX]

sounds like ur thermostat might be faulty.. if it gets stuck shut then water wont be circulating through the rad and getting cooled... thermostats can get sticky or even just jam shut try this first.. its a very easy thing to sort out.. thermostat housing off.. thermostat out.. then get boiling water and put it into it... see if it opens every time nicely