E39 Temp Gauge

[Jansi]

This weekend my Temp Gauge started randomly going into the red, then dropping straight back down to normal with in 5 seconds.

There is no signs of overheating ie loads of steam.

Any ideas?

[numbnuts]

I would have thought it was the thermostat playing up,,unless you got a fd gauge of coarse..

[M3 Mitch]

I *think* these gauges are run by the ECU in a "buffered" fashion, so that they read middle of scale until the coolant exceeds some threshold which I think is about 250F. Apparently focus group weenies were complaining that the gauge moves around a bit as engine load varies. To which the proper reply would be "yes, that's the way it works" but instead some idiots tried to engineer out the numpty-annoying movement. So you get a gauge that's about as functional as GM's famous "way too hot" idiot lights....

So perhaps you have a borderline overheating situation.

Or maybe it's just a bad connection at the sending unit, or a bad ground on the dash gauge?

One of the reasons I stick with my E30 M3 and am not at all tempted by BMW's current offerings.