My temp gauge is acting up, I think.  85 Westfalia (automatic), 2.1l Boston Bob rebuild with about 20k on it.

Coolant levels seem fine in both tanks (although by fine I mean that I seem to have to add coolant to the new motor, same as i did with the old, for no apparent reason ...)

Today I'm driving about five km to the store.  The gauge is fine, then shoots up, then comes back down, then up again.  Then the light starts flashing, then stops.  Then the gauge goes back down to normal.  I'd been driving for a matter of blocks when it first pegged.

Normal is slightly below where the light is located.  Used to be right at the light with the old motor, but at some point (not sure exactly when) the gauge started reading a little lower, and the gas tank did as well.  Maybe the voltage regulator.  Sorry for the red herring.

Any thoughts?  Goofy gauge or something more sinister?  

Thanks as always
Jeff