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Hello All: after the drain/refill is complete, with turning heater on high heat/low power and getting engine to normal operating temps:


1) are these done simultaneously
2) is the expansion tank cap ON or OFF during this process


I have seen conflicting suggestions on this and just looking for some guidance before I tackle this.


Thanks!
 

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You really don't have to bleed an E39 M5 since the expansion tank is the highest point in the system. I don't even think there is a bleed screw. The way I've done it is to turn the key to run (engine off) and set the heat to max so the heater valve opens all the way and the aux water pump is running. Then just fill slowly until it's at the full cold mark. Put the cap back on and go drive it and get it warmed up all the way. Then recheck the coolant level after the car has sat overnight and had a chance to fully cool down.
 

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Agree with above... you don't need to do anything IMO. I just replaced my t-stat a few weeks back. All I do is fill it to the line, start it up and while it's warming up I just make sure the tank stays pretty much topped off. Then I do a test drive, park it overnight so it's fully cooled down and then top the tank one last time. This method has always worked for me.
 
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