Overheating issue - help

[harry13789]

Had the radiator changed on my 01 cooper in march but I'm getting engine overheating and cold air blowing through the vents when the heatings on (although i do get hot air sometimes). I've got water/coolant in the expansion tank which doesn't look like it's depleting so I'm guessing there is not a hole in the system (will confirm tomorrow). The engine is overheating when idling and at a standstill although the fan is kicking in and over running when the car is switched off. Now I'm assuming the problem could be either air in the system, a blockage or maybe the thermostat. Lost on this one guys so any help would be appreciated.

Thanks

H.

[mab01uk]

The radiator fan has 2 speeds, sometimes the low speed resistor fails so only the second speed ever cuts in at a higher temperature causing overheating.

Other common fault is an airlock in the cooling system, there are 2 or 3 bleed valves under the bonnet which need careful bleeding, especially to get air out the heater..........airlocks cause heater to blow cold as water can't circulate properly.

This link may help:
Solving MINI Cooling Problems.......... - Forums

Bleeding:
http://www.mini2.com/forum/maintenan...g-coolent.html

http://www.mini2.com/forum/maintenan...screw-plz.html

[maxb92]

I have this problem too, but that's because my radiator seems to be leaking.. Sorry to go off topic but who did you rad and how much did it cost you? I got quoted £230 yesterday and that seems a little steep?!
Thanks in advance.

[harry13789]

I got mine done under a warranty that came with the car. No idea what the cost would have been. I know the garage said that if you have air con it'll take a lot longer seeing as it's much tighter at the front of the engine bay. Had the cooling system pressure tested an refilled this morning and they didn't pick up any leaks. Got it back home and the coolant in the expansion tank was above the min mark. Looked at it half hour ago and it had dropped about an inch. I'm hoping this is just from the expansion of the water but I went out for a drive, got it up to temperature and the coolant hadn't risen up to the previous level. Thoughts?

[mab01uk]

Coolant level may take a few days to settle as air works its way out, keep an eye on it for a few days and don't ever let it drop below 'Minimum' or you may get an airlock.

[harry13789]

Right I'm completely lost. Coolant level in the expansion tank had dropped even further below the min mark so I topped it up midway between the min and max mark with water about 3 hours ago. Left a bit of cardboard beneath it to see if there were any leaks elsewhere (like the expansion tank as I have read this is prone to leak. Just looked at it now and it has dropped below the min mark and there is no liquid or marks on the cardboard. I've rearranged the cardboard so it now covers the whole of the radiator area and the front half of the engine bay so I can see if there is a leak there. There is no White stuff in the oil filler cap so the coolant can't be mixing with the oil. Completely stuck :S

P.s. Just to clarify the expansion tank is there for when the coolant heats up and expands so when the car is running and up to temperature the coolant level shall rise.

Thanks.

Harry.

[harry13789]

Thanks for the reply mab01. I'm a little less nervous after I read your post. Should I keep topping up with water or a mix of anti-freeze?

Thanks.

[mab01uk]

Keep topping up for a few days and see how it goes, if no obvious leaks then it is probably air working its way out causing the level to drop. Mini's are notorious for getting air trapped in the system after a coolant drain and refill. Top up with the correct antifreeze or a suitable coolant mix. It is better to have a little too much antifreeze than not enough. (clean up spills as it is poisonous to pets and animals).

If no improvement or overheating after a few days return to your garage.

[harry13789]

Thanks for the info. Will try this and update you. Do I need any special stuff to put in from BMW or can I just go to Halfords and pick something up?

Thanks.

[mab01uk]

Quote: Originally Posted by harry13789 (original)

Thanks for the info. Will try this and update you. Do I need any special stuff to put in from BMW or can I just go to Halfords and pick something up?

Thanks.

Ideally BMW/MINI though expensive ensures the correct spec is used or find out what your garage used.........some types of modern coolant/antifeeze do not mix well.

[lobosmom1]

Hi everyone My boyfriend recently purchased an 06 mini and he's had it since november, about a month ago when driving one rainy night we noticed water on the passenger side floormat and when i felt around with my hand it was dripping / collecting on some black plastic box above the mat, I smelled the fluid on my fingers and it didnt appear to be coolant, the next morning the spot was dry, I wondered if it was some sort of seal leak and maybe rain water found it's way between the body panels ? it didnt happen again for a few weeks and we had even been driving in very rainy conditions with no issues.
A few days ago however he was on his way to work and the whole time the temperature was reading normal at half and the heater was working properly, but he noticed once you were idling the heater stopped blowing warm air, and the temperature gauge started climbing quickly, after revving the engine 2- 3 times the temp gauge went back down to half hot the heater still wasnt blowing warm air.
For the past week the car runs at normal temperature and the heater seems to come and go and the car will over heat only when idling or if driving under 5 mph for more than a minuete. Could this be a bad heater core , thermostat, or is it something else? this is his first mini cooper and were unfamiliar with any factory recalls, or if this has been an issue for anyone else, any and all advice/ knowledge is welcome

Thanks !!!!!

[mab01uk]

Check heater core, blockage, air locks and thermostat but also check the low speed of the radiator fan is working, this can fail due to a resistor burning out, then meaning only the high speed fan cuts in at a much higher temperature by which time the engine is overheating especially when idling or stationary in traffic.

[harry13789]

Right the weekend is over and the coolant still seems to be depleting from the expansion bottle (albeit at a much slower rate) which leads me to think it's starting to settle. I will be taking it down the garage tomorrow to get some uv dye put it in so they can establish if there is a leak from somewhere. Good idea? Thanks.