[20thebear]

Any advice on possible causes of this would be greatly appreciated.

I have been out of the country for a week, so my 52 Cooper has been sat in the yard.

I took it out on saturday and drove 2 miles, where the car was then parked for approx 10 minutes. I then drove the car for another 4 miles, and pulled up to drop someone off. When one of my passengers noticed that the water temp gauge was rocketing from the normal position. It even hit the point where the red light came on. So i quickly turned on the interior heater to max and the fan on to max (4) as well. This quickly brought the temp back to normal.

I then started driving again and reduced the fan by one click (3), and the temp started rising again, so i turned the fan back up again. (and the temp dropped)

i drove for about 4 miles and stopped at the shops. when i got out of the car the cooling fan was going, and when i put my hand in front of the grill i could feel cold air hitting my hand.

once i finished the shopping and returned to the car the fan had stopped. on restarting the ingintion the temp gauge went straight to the normal position. i drove home with the fan on full just to make sure i got home.

i opened the bonnet to check the radiator expansion tank and the was only a little bit of coolant in it. it was well below the min line. i have topped it up (it only took about a mug full to get to a normal level), but not had chance to run the car out again with the heater/fan off to see what happens to the temp.

the air temp when this happened was 17 degs, so it is not like it was a red hot day, and i hadn't been thrashing the car. i had a look on the dip stick to see if there was any white sludge (i.e the head gasket had gone and the coolant/oil had mixed), but it looked ok.

does anyone have any ideas?
has this happened to them?

is there a bypass valve in the cooling system that could have failed / jammed?

thanks, B

[dietcokeplease]

Well you've checked the coolant and fan. So maybe the valve is working intermittently or the water pump is iffy. I'd take it to the Stealer for a pressure check.

[20thebear]

so is there a bypass valve / solenoid? any idea where it is hidden? i'll give it a knock with a hammer to see if it frees off ;-)

[Capsaisin]

The thermostat on the Cooper is part of the coolant filler neck, at the rear of the engine. It could have jammed, but a week standing is not really a long time?
Maybe it was an airlock?
You might get a better idea when you get the chance to take it out for another run.

ps
Didn't think a Cooper had an expansion tank?

[20thebear]

Quote: Originally Posted by Capsaisin

The thermostat on the Cooper is part of the coolant filler neck....

ps
Didn't think a Cooper had an expansion tank?

Is the expansion tank (possibly the wrong name) not the clear plastic tank, with blue fluid in it at the back/ middle of the engine bay?

[20thebear]

I have just found info on a fault with the old tanks.

"They replaced the old leaking coolant tank with the new design. The old tank is made of a white plastic and tends to leak from the seam. The new tank looks the same except that it's more of a yellowish color. The part number is 17 13 7 529 273."

I will have to see if the tank has been leaking.

[Root Ginger]

It's quite common to get leaks from the tank or from the fluid drain clamps. These are located between some of the hoses and are made of plastic. They have a plastic screw that goes into them.

[hypergear]

I know this is an old thread but my R50 is doing the same thing, it has the white plastic coolant tank. Has the replacement yellow one been a success?

Thanks.

[captint]

I had the same thing on my MK 4 golf and it was the water pump. Heting sorted out for a while, but it got a tad sweaty, also running it for more that a couple of days could cause engine damage

[hypergear]

I have a new water pump and a new radiator, it has been blead twice now each time being ok for a week or 2 then began overheating again. Yellow plastic tank replacement seems like the next step from what I have read so far.

Anyone else had this problem before and have sorted it out?

[MINIMANIAUK]

The COOPER and COOPER S have a fundamental difference in the cooling system - the COOPER S has a pressurised system the ONE/COOPER does not
The S due more Power output ,needs more cooling and pressurising the systems raises the boiling point by 20degrees of the coolant
Due being a pressurised system the expansion /header tank has screw top with pressure relief in it , the pressure can cause the tank to split at the seams (early ones)
This is also why the S can have heater matrix leaks,and radiator splits on the side.
On the COOPER leaks can appear at the thermostat housing and split rubber pipe leading to the heater due chaffing( its near the air Filter at the back of the engine.
On turning off the engine the system cools and coolant from the expansion tank gets sucked back into the system ,if you have a small leak anywhere it draws in air - this requires bleeding AND rectifying the leak.
As the cars are ageing rad hoses go soft and collapse,water pumps lose efficiency due scaling and corrossion (especially if coolant chages not done) belts stretch and slip ,thermostats can stick,radiators can block( coolant changes again)or get full of bugs and dirt.
If air con fitted the aircon rad can get blocked and reduce air flow to the cooling rad behind it .
thermo switch for the electric fan can also fail ,and the bc1 can have issues with both the guage and fan control.
If you simply rely on bleeding the system , it could get expensive( £1000s ) for the want of a £10 pipe!! -If you are not a DIY person ,(and I always reccommend you have a good look yourself) then take the car somewhere and get it checked!
A