C1 Temp Gauge Fluctuating

[Joe P.]

I have been dealing with a "cooling issue" for some time now, at first it would puke out thru the rad cap, so i changed the rad cap, the thermostat, replaced the sending unit with one from Lectric, new fan clutch, tested rad flow and pressure, swapped out the gauge... still getting wild swings in gauge readings from 180 to +220, when driving around.

I dont believe its overheating but I would like to know when it really does some day, before it "blows".

Today on the way to work the gauge read 220 and stayed there for a few minutes, I pulled over took the IR gun the the top hose at the outlet of the block 168 degreees, hit the thermostat housing 185 degrees.

I am starting to suspect the gauges... Is there any way for a non highly technical person like myself to test the gauge to see if it needs recalibrating.. I dont know the history of the gauges.

Any recommendations on where to get the gauges recalibrated?

Thanks.
Joe

[Jack H.]

Re: C1 Temp Gauge Fluctuating

Such fluxuations can be the result of a 'Bubba' install of the instrument cluster...

Pointer needle gauges typically work with two opposing electro-magnets. One pulls the needle this way, the other pulls it the opposite way.

One electro-magnet has a fixed path to ground (constant current and constant magnetic strength). The other runs through a variable resistor ('sender' unit) causing the current through the magnet to vary and the magnet's field strength to change in lock-step. This gives the pointer needle 'stiction' making it resistant to changing position due to road shock/vibration.

That said, if one electro-magnet 'loses' its ground path, its pull strength evaporates and the pointer needle will 'jump' in the direction of the electro-magnet that's still working.

Typically, the fixed electro-magnet gets it's ground path via the gauge being properly screwed into the instrument cluster AND the ignition switch having good contact to the dash harness (there are both BAT and GND terminals on the ignition switch) AS WELL as the ignition switch being TIGHTLY torqued to the instrument cluster via the switch bezel.

Instead of replacing various 'suspect' components at random, I'd put science to work and verify each component AND its inter-connect wiring is working properly...

[Joe P.]

Re: C1 Temp Gauge Fluctuating

Such fluxuations can be the result of a 'Bubba' install of the instrument cluster...

Pointer needle gauges typically work with two opposing electro-magnets. One pulls the needle this way, the other pulls it the opposite way.

One electro-magnet has a fixed path to ground (constant current and constant magnetic strength). The other runs through a variable resistor ('sender' unit) causing the current through the magnet to vary and the magnet's field strength to change in lock-step. This gives the pointer needle 'stiction' making it resistant to changing position due to road shock/vibration.

That said, if one electro-magnet 'loses' its ground path, its pull strength evaporates and the pointer needle will 'jump' in the direction of the electro-magnet that's still working.

Typically, the fixed electro-magnet gets it's ground path via the gauge being properly screwed into the instrument cluster AND the ignition switch having good contact to the dash harness (there are both BAT and GND terminals on the ignition switch) AS WELL as the ignition switch being TIGHTLY torqued to the instrument cluster via the switch bezel.

Instead of replacing various 'suspect' components at random, I'd put science to work and verify each component AND its inter-connect wiring is working properly...

Thanks Jack, i will put some time into your suggestion..