Mini Cooper S R56 First registered 2007 - Overheating

Honest John Back Room » Technical matters
View Threaded
Wed 19 Nov 2014 09:07
Mini Cooper S R56 First registered 2007 - Overheating - Denzil
i was recently held up in traffic and with out any warning my car started to boil up ,no dashboard warning lights no audio warning ,I checked coolant level this was ok ,the engine coolant fan did not cut in .Having got the vehicle home I shorted out the coolant fan relay and the fan started to work I do not think the thermostat is at fault .i have accessed the hidden menu and the car runs at about 100 C ,I have sinned changed the engine coolant sensor my worry's are that this issue may occur again ant ideas would be appreciated.

Along the same lines I was thinking of purchasing the Delphi DS150E diagnostic tool that a local retailer is selling for £110.00 would this equipment help me solve the fault
Reply | Report as offensive | Link
Wed 19 Nov 2014 11:58
Mini Cooper S R56 First registered 2007 - Overheating - Railroad.
Go back to basics. Is the radiator hot all over when the fault occurs? If it isn't or if it's hot at the top and stone cold everywhere else then it does not matter if the fan cuts in or not, you have a problem. The cooling fan draws heat from the radiator when there is no airflow, such as in traffic. If there's no heat in the radiator then the fan running will make no difference at all. If the coolant level is ok then you either have a faulty thermostat, blocked radiator or worn or broken water pump. Try drawing heat away by setting the heater to hot and opening all the windows with the blower on full speed. The engine should begin to cool and the temperature gauge should fall. A hot heater is also a good indication that the water pump is in good condition.
Reply | Report as offensive | Link
Wed 19 Nov 2014 19:55
Mini Cooper S R56 First registered 2007 - Overheating - Denzil

Railroad thanks for the speedy responce.

At the time it happened i did not think to check check the heat at the top and bottom of the radiator , and touch wood it as not happened again . one thing i did not mention is 3 weeks ago i had a new piston and liner fitted i just wonder if the garage did not get all the air out of the system having said that i still did not get any dashboard warnings would you know what sensor controls the warning systems.

The heater functions correctly

Reply | Report as offensive | Link
Thu 20 Nov 2014 08:44
Mini Cooper S R56 First registered 2007 - Overheating - Railroad.
Far too much is made about bleeding cooling systems. Yes of course it's essential that the system is properly bled but doing it isn't an exact science. The difficulties arise when the thermostat is closed because the system is then effectively divided into two. Older Renaults were the easiest cars to bleed because the bottle from where you fill them could be held up high creating a head. The system then filled easily and completely with the bleed screws open.

Back to your car. Air can become trapped in the block as the system is filled because it can't escape. This is why a thermostat has a hole with a jiggle pin to keep it clear. The best way to bleed a system is to remove a component such as a temperature sensor which is located at the highest point, and fill until coolant appears there. On more stubborn systems it usually works to fill the system from various places such as the radiator top and bottom hoses, and even the heater hoses. Bear in mind that the water pump is a centrifugal pump and only works when it's submerged. They are designed for high flow and low pressure, and move liquid very well indeed. Regardless of how fast you spin the impeller it will not effectively move air, and so running the engine with air in the system is not the best way to remove it.

Edited by Railroad. on 20/11/2014 at 08:49

Reply | Report as offensive | Link
Thu 20 Nov 2014 09:03
Mini Cooper S R56 First registered 2007 - Overheating - elekie&a/c doctor

I think it may be a good idea to check the operation of the water pump system.These have an "on demand " water pump which means that the pump is only driven/rotated when required.There is an electronically controlled friction drive that decouples the pump from the main drive pulley/belt.

Reply | Report as offensive | Link
Thu 20 Nov 2014 09:53
Mini Cooper S R56 First registered 2007 - Overheating - Andrew-T

This exact problem happened soon after my daughter got her Mini of a similar age. The selling MINI dealer replaced (I think) the sensor unit under warranty which cured the problem.

Reply | Report as offensive | Link
Fri 21 Nov 2014 12:40
Mini Cooper S R56 First registered 2007 - Overheating - Denzil
Thanks guys to all the advice that you have given ,I have just changed the engine temperature sensor (the one now in is an O/E part) run the engine up and at just over 108c the fan cut and brought the temperature down to 100c I think I have put to issue to bed once again thank you
Reply | Report as offensive | Link
Thu 20 Nov 2014 12:41
Mini Cooper S R56 First registered 2007 - Overheating - Cyd
,.......the engine coolant fan did not cut in ..........Having got the vehicle home I shorted out the coolant fan relay and the fan started to work

The OP mentioned that the fan did not cut in and that he had to defeat out the relay to get the fan to run. This would suggest the relay needs replacing - but the OP doesn't mention having done that. This could cause overheating in traffic.

Reply | Report as offensive | Link