TESTING '57 GAUGES
Note : these tests are made with sending units removed from car
OIL PRESSURE: I use an air compressor and blow air through the fitting at rear of gauge. Be careful ! Don't use full pressure of the compressor !
|
No pressure ( 0 psi) |
Reading : 0 or "low" |
| Pressure = 3,2 bars or 50 PSI | Reading: 1/2 of scale |
| Pressure = 6 bars or 90 PSI | Reading "high" |
TEMPERATURE: the dash gauge is wired to :
- + 12,5 V DC supply
- to some solid resistors (other end of resistor to ground) : R in the table below
- ground
| R = 240 to 270 ohms | Reading : 0 or "cold" |
| R = 45 to 51 ohms | Reading: 1/2 of scale |
| R = 12 to 15 ohms | Reading "hot" |
Below you'll see the temperatures readings on my '57
Imp. gauges, see table to convert in °F. Remember that normal T° is between 170
and 190° F (thermostat opens at 160 or 180, depending if car is non A/C or A/C).
So in normal conditions the needle must not go after the middle mark.
i test the sending unit in a boiling jar with digital thermometer. The unit was
wiring to the dash gauge.
| temp in °C | 30 to 40 °C | 60°C | 75°C | 88°C | 98°C |
| temp in °F | 86°F to 104°F | 140°F | 167°F | 190°F | 208°F |
GAZOLINE : the dash gauge is wired to:
- + 12.5 V DC supply
- to the tank unit (removed from tank)
- ground
The tank unit is wired to:
- dash gauge
- ground
You move the arm to different positions according to the reading of the gauge ; at each position you shut off the supply and measure the resistance between tank gauge pin and ground:
| R = 170 ohms | Reading : "empty" |
| R = 78 ohms | Reading: 1/2 of scale |
| R = 26 ohms | Reading "full" |
Note: i 've not tested the amperemeter gauge, i haven't any power source ..