Quote:
Originally Posted by pbonsalb
I am not sure the diagram shows incorrect flow direction for the auxiliary engine coolant radiator. It is auxiliary and may serve to further cool the main radiator cold side output and feed that back into the main radiator hot side input. But I don’t know for sure that is how the system works.
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I see what you are saying but it shows cold water coming in and hot coming out. So, I'm pretty sure it's a typo. It is interesting that the diagram in the S63TU guide looks completely different because the aux coolers are charge air only. And that version also had water supplied to the DME. But the S63TU4 guide says "vehicle dependent" which of course makes more sense.
Either way the whole systems has lots of complexity...4 electrical pumps and 1 mechanical, complicated thermostat and sensors.
I'll probably do the thermostat at 100k miles like I did on my wife's E90...the thing is complicated enough that it won't last forever, and I'd rather replace it early enough to no get stuck and enjoy it vs replacing it right before selling or something. Not sure about the electric water pumps. I did that on the N54 as well but that was back when BMW had a bad rep for cooling systems. Not so sure now.
And depending on how things go for others I'll replace the expansion tank.