Temperature gauge/thermostat mystery

[LeicaBimmer]

I recently changed out the thermostat on my 89 3.25ix after the temperature gauge began bouncing from the lower third to the upper third of the dial and all points in between. After the the change the the gauge stayed well within the operating range and rock solid. After about 2 months the gauge started to do the same thing all over again. I had the system flushed but no change. Is it possible to have gone through a new thermostat that quickly or is there something more to this as in the temp gauge or something else upstream. Any help would be greatly appreciated.

[BMWJNKY]

The sending unit may be going bad. They cost arround $20 for a new one.

[bddog]

fan clutch, water pump or both-------Steve

[BimmerKris]

if it is bounceing, it is probably the guage, mine did that, and when i would tap on the gauge console it would correct itself... untill the needle broke and fell off that is.

[broketiltuesday]

Try taking off the lower bit of trim beneath the steering wheel (three plastic bolts and a clip near the foot pedals) then stick your hand up behind the instrument cluster and try wiggling the connector behind the temp gauge about.

This seems to have fixed my erratic temp readout (sometimes used to creep up to the red but a tap near the gauge would set the needle back to halfway and it would stay there).

[MrM3]

if the needle bounces or floats around in the gauge then tighten the nut behind it on the back side of the cluster, that usually solves the problem for most people.