So, what is the purpose of the arrow on the thermostat anyway? I used to think those were on the models which had the little bleeder valves in them but I noticed there is an arrow on the MB one I just removed even though it has no bleeder...why does the arrow need to point up? It seems like the thermostat is symmetrical and there is nothing special about it when it points up.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz