Noticed something odd today... 5 hours after parking my car in my garage,
I'm working on it with the hood up, and notice a noise like something is
releasing pressure very slowly. I trace it with my ear back to the coolant
reservoir tank. So I loosen the cap, and quite a bit of pressure PSSHHHSes
out, along with a squirt of coolant. Now that would be normal behavior if I
had just been at operating temperature, but this coolant wasn't any more
than 60 degrees F. What would cause such pressure to build up in there? I've
noticed this car warms up much more quickly than my older 740t, and once the
temperature is up, it stays up (as opposed to my old car where I could get
the needle to drop by coasting for a long while).
Any ideas?

Thanks

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