Water Temp gauge calibration

[Kelvin]

Since installing my FiTech fuel injection I've displayed the water temp
on the handheld screen. This told me I was running 145° going down the
road with outside temps near 32°F. The VDO gauge on the dash was
registering ~180°.

I've taken this Christmas trip for over a decade now and just assumed
the GMC had a lousy heater. After covering half of my radiator with a
garbage bag I was please to find I had a pretty good heater. The FiTech
gauge was around 175-180° and the VDO gauge was now registering around
230°.

I have since installed a 195° thermostat and at 55°outside temps my
FiTech gauge says I'm running around ~185° and the VDO gauge is still at
230-ish.

Is there any way I can calibrate the VDO gauge to reflect what I think
is the correct coolant temp? Will a resistor inline change the signal
sent by that sender? A potentiometer so I can dial it in? I know just
enough about electrons to mostly stay out of trouble.

Thanks,

Kelvin
'73 23' in Eugene, OR

 

[roy keen]

I suspect you may have the wrong VDO temperature sending unit for your gage. I would verify the part number on your gage and order a new sending unit.
You could shoot the temperature sender with a lazer temp device to double check your findings.
--
Roy Keen
Minden,NV
76 X Glenbrook

 

[thomas phipps]

I purchased several VDO temp gauges; oil, trans. They both came with the same sensor, no difference in part number or function.
Tom, MS II
--
1975 GMC Avion
KA4CSG

 

[Kelvin]

You do buy sensors based on the gauge. I have a 0-250° gauge and can
only assume I bought the 0-250 sender. I should probably see if I can
find the receipt, but I would hope I was smart enough to do that.

Kelvin

> I suspect you may have the wrong VDO temperature sending unit for your gage. I would verify the part number on your gage and order a new sending unit.
> You could shoot the temperature sender with a lazer temp device to double check your findings.