Yes, the gauge can be wrong. More likely is the dash voltage stabilizer
which is used to convert the nominal 12V of the electrical system to a
regulated 10 volts. This is the voltage that runs the temp and fuel
gauges and makes them read consistently whether the engine is running or
not, and not bounce around when there are loads on the electrical system
such as headlights, A/C or the front cooling fan. These are ~$10 so get
a new one and see if it fixes the problem. If the stabilizer is
drifting, the 2 gauges will both read either high or low. You can
measure the voltage at the legs of this 10 volt DC regulator by removing
the dash cover and looking at the area above and behind the speedo. 10.0
is ideal, the Bentley call for between 9.5 and 10.5 I think.

Mark

KENWILFY@AOL.COM wrote:
>
> Thanks for all the input about the cooling system overheat problem I was
> having.
>
> Here is what I found:
>
> The van would warm up rather quickly to about 3/4 on the temp display.  I
> figured this was overheating and I would shut the van down.  However, I got
> so mad today that I just said, "Keep it running".  Well it ran at the 3/4
> temp and didn't rise.  I noticed that the lines to the front heater core were
> full of air.  I opened up one of the lines until a little coolant came out
> (this bled the heater system and that started working).  Then we felt the
> radiator starting to get warm.  Finally the radiator got hot and the fan came
> on as the gauge still showed about 3/4 hot.  The fan cycled on and off like
> normal and both heater hoses were hot.  So, I replaced the gauge sender
> (thinking it could be bad) and it still acts the same way.  The only thing I
> can come up with is that the gauge is wrong somehow and that the motor is
> running at normal operating temps (this is confirmed by the brand new raditor
> fan switch cycling on and off while the gauge shows 3/4 hot.  I have bled and
> bled the system and all the lines now seem to be full of coolant and all of
> them get hot after the van runs for a while.  So I assume I am at normal
> operation here.  Anyone else have the problem with their gauge reading high?
> Can it be adjusted somehow?
>
> Thanks for all the help,
> Ken Wilford
> http://www.vanagain.com
> John 3:16
> Phone: (856)-765-1583
> Shop:   (856)-327-0027
> Fax:     (856)-327-2242