Problems with the thermostat housing in the Mini R56.

[CrawlerTagz]

Greetings, gentlemen. I own a 2011 R5T LCI engine and recently replaced the water pump without any issues. However, when I attempted to refill the coolant, I encountered a problem. I was unable to fully replenish the coolant, which amounts to approximately 5.2 litres. I tried various methods, such as squeezing hoses, using the bleed screw, raising the car, and raising the expansion tank. It is worth noting that my car is an LCI model with a slightly different thermostat housing. Unlike other models, the temperature sensor is not located on the housing but rather in the hose connected to the expansion tank. I have been informed that there are three types of thermostat housings available. Consequently, I began to question why this issue occurred. Could it be due to a failure in the housing? Am I performing the bleeding process incorrectly? Although the heater is generating some warmth, it is not sufficient, and the engine is becoming excessively hot too quickly. Is the housing itself in good condition? I purchased the wire harness for the housing and used the existing harness to establish a connection between the power supply and the housing. However, despite this, there was no response from the thermostat, which I expected to open upon receiving power. It is possible that the thermostat is now locked in the closed position, so preventing the flow of coolant. However, because the housing is regulated by the electronic control unit (ECU), is it activated when the housing is at a low or high temperature? However, when I measured the voltage from the harness, it was found to provide 12 volts to the housing while the automobile engine is cold. Does anybody know the expected operation of this system? Idiotic miniature, Here's a helpful tip, gentlemen: while purchasing car components, consider searching for Citroen or Peugeot brands, since these parts tend to be more affordable.

[DownContent]

The correct voltage for the thermostat is 12 volts on the common wire. The electronic control unit (ECU) controls the on and off switching of the earth wire to activate the thermostat. As for the capacity of the coolant system, it can hold up to 5.2 litres when completely empty. However, there may still be some coolant remaining in the radiator and heater matrix, as they have lower points than the engine coolant system. To fill the system, fill the header tank halfway and open the bleed screw on the thermostat housing to release any air. It is helpful to have the passenger side of the car elevated higher than the driver side to facilitate the release of air towards the bleed screw. I recommend running the system until the hoses become firm, then shutting it off. This will allow the system to purge itself of any remaining air.

[CrawlerTagz]

Thank you for your response. I had completely removed the coolant from the system using compressed air. My intention was to refill the system with a minimum of 5 litres of coolant to ensure that I had about the proper quantity. I was only able to introduce around 3 litres into the system, and the coolant was flowing out of the bleed screw. My hypothesis is that the thermostat housing is currently stuck in the closed position and fails to open when the 12v power supply is connected. I have attempted to manually open the thermostat by applying 12v directly from the battery, but I am unsure whether the thermostat is supposed to be open or closed when the engine is off. Ideally, I would expect it to be closed, but I am observing a 12v reading at the housing when only the ignition is turned on.
My plan is to test the functionality of the new housing by supplying it with a 12-volt power source. I will observe if it opens or not. After removing the previous housing, I will repeat the same process. If it opens, I will be in a difficult situation. If it remains closed, I will know that the housing is damaged.

[DownContent]

I have never performed that procedure before. Typically, I have only bled them by using a bleed screw and monitoring the pressure in the system. It may require several attempts of heating and cooling, with refilling in between. It is important to avoid running the system for too long, as this will cause the pressure to be expelled from the header tank cap. Instead, allow the pressure to build up to about an inch from the top, then shut it off and let it cool. Upon returning, you will notice that Introducing stray battery voltages into inappropriate locations is a hazardous practice.

[CrawlerTagz]

This is an unusual situation. I am knowledgeable about the functioning of the car, and I can confirm that all components were working properly. The fan operated as expected, there were no issues with overheating, and the tensioner pulley for the water pump was functioning correctly. Therefore, everything seemed to be in order. However, my problem arose when I decided to change the water pump, which I believed was a simple task. The replacement went smoothly, but subsequently, a new issue emerged. Currently, the coolant fan fails to activate when the engine reaches the appropriate temperature. Interestingly, if I remove the engine temperature sensor, the fan switches on as it should. Initially, I suspected that the fan relay might be the cause of this problem. However, I have thoroughly inspected all relevant components and everything appears to be in good working condition. (Could there possibly be another fuse that I am unaware of?) If the coolant housing is in a closed position that cannot be moved, it is most likely that this is the correct explanation for the issue at hand.

[DownContent]

The fan relay is not the issue here. These engines do not activate the fan until the temperature reaches 110 degrees Celsius, which is normal. The engine operates at a running temperature of 105 degrees Celsius. The thermostat housing remains closed until it heats up, allowing some cold air in to regulate the temperature at 105 degrees Celsius. To diagnose the issue, I revved the engine to 2500 RPM while monitoring the coolant temperature using live data. I also observed the header tank to check Another method to release air from the radiator is by disconnecting the small pipe attached to the header tank corner and blowing air into the header tank to expel air through the radiator. This technique is effective in bleeding air from the radiator and I have to perform this process on at least four engines every month, sometimes even on a weekly basis. The hot water flows down through the radiator as the top radiator hose heats up first, similar to how one-way pipes are installed in the heater matrix to ensure proper flow.

[DownContent]

The reason the fan kicks in when an open circuit is induced to the temperature sensor is to default protect itself and communicate this to the electronic control unit (ECU). This is a normal and necessary function. On some automobiles, the fan relay or relays may be identified as green relays located in the fuse box under the hood. Additionally, there is a fuse dedicated to the fan relays on the switching side.

[CrawlerTagz]

I highly value your advice and expertise. I intend to implement your suggestions once the inclement weather in the north east subsides. Regarding the thermostat housing, am I correct in assuming that if it is stuck in the closed position, it would prevent coolant from circulating throughout the entire engine? Furthermore, if I were to directly apply a 12-volt current to the housing while the car is completely turned off, would this enable the flow of coolant?

[DownContent]

Adding a live to it is unnecessary and introduces uncertainty. It is advisable to loosen the higher pipe from the heater matrix to allow coolant to drip out, which will eliminate any air trapped in the system. However, it is worth noting that I have worked on well over 1000 engines of this type over the years, and they are designed to bleed in this manner. If pressurisation in the coolant system persists even after bleeding, it indicates more significant issues. Typically, after driving for an extended period and then allowing the engine to cool, all air is expelled from the system. This is observed in all engines of this type, as they go from being halfway filled to nearly empty after bleeding. To achieve this, I recommend running the engine at high revs for an extended period or applying back pressure to the header tank, as I previously mentioned. I apologise if I am repeating myself in this thread, but the method I described above has been proven to be effective and has been tried and tested numerous times. In fact, I will be using this method again on a Cooper S that I have recently worked on and refreshed.