After topping up my coolant with a bit of water, my temperature gauge is
under reporting my temperature by A LOT.  On two 11 mile trips, the
needle barely got passed the first line (and never left the small
initial zone marked on the gauge that makes up the first 1/8 of the
gauge or so).  I still had warm air coming out of my front heater vents,
and it didn't over heat.  What is going on??

Thanks for any help,
Wes
'84 1.9l