I am fixin to test start my rebuilt engine
tomorrow and, while running through the systems this evening, I noticed something unexpected.
temp and oil
pressure gauges show values when no power is applied.
When the batter switch is turned off, the water
temp shows about 140 degrees and oil
pressure shows 20 psi.
When I turn battery
switch to on, water temp gauge pegs out on the zero stop. It hits pretty hard with an audible click when it smacks against the stop. The oil pressure gauge gently goes to zero.
It makes sense that the gauges show zero when ignition system is energized, but is it normal for gauges to have readings when no power is applied?
It's been so long (7 months) since I've run the engine
and I never paid attention to the position of the needles when system was off.
The engine is not on and the negative wires from gauges go to the negative bus, which is connected with negative post on battery
Positive wire goes from positive bus to the first gauge and they are connected in series.
2/0 cable connect negative post on battery with unpainted exhaust
2/0 cable runs from pos batt post to on/off switch, then to the starter stud.
Sense wires are the red wires on the lower left (to left of positive stud/wire) on each gauge