I've heard this is a common problem amongst BMWs, and now it's happening to me. The thermostat my 528i is messed up, the flow of the antifreeze is too much and the engine can't get to normal working temperature. I've already bought a new thermostat, and was planning to replace it until I saw where the part lies. It lies, in the most inconvenient position in the whole goddamn engine, right between the engine itself and the fan, which is attached to about 20 pipes that I don't even know what they're for or where they lead to. The dealership wants about $300 to replace it, which I’m trying to avoid, while at the same time also trying to avoid taking apart the entire radiator for this one part. Has anyone experienced this on his or her 5-series, and if you have, what did you do?