C-3 gauge question

[Mark A.]

I would like to bench test my water temp, and battery gauge, before reinstalling it in the car. Could someone please give me directions on the correct way to test these gauges? Thanks, Mark

[Mark #28455]

checking water pump for leaks

Go to the local hardware store. In the sewer plumbing section, purchase a black rubber cap for the inlet hose hole and attach it with a hose clamp. Also cap off the bypass hose bib in a similar fashion. Get two small pieces of 1/4" steel and using water pump gaskets as a template, drill holes so you can bolt them on to block the passages to the engine block. Drill one of the plates and tap to screw in an air fitting that attaches to your compressor. Then using a regulator, apply 15# pressure and spray the outside of the pump with a soapy water mixture (dish soap in water) if it bubbles, you have a leak - just like pressure testing a block and heads!

Mark

[Mark A.]

Re: checking water pump for leaks

I am looking for help to electrically bench test the water temp and battery gauges. They are not in the car. The car is disassembled right know. Thanks, Mark

[Mark #28455]

whoops! pump, temp same thing! *NM*

[Jack H.]

Re: C-3 gauge question

For the temp gauge, first use an automotive style battery simulator as your power source (13.8-14.2 VDC and NOT 12 VDC) because you want to simulate reality (engine running with alternator/generator actually active and charging). Place a 50 ohm resistor on the temp gauge's output (to sender) to ground and the gauge ought to read in the 240-250F range. Swap that with a 100 ohm resistor and you should see a mid-gauge reading in the 180F range.

On the ammeter, most simply do a gross integrity check by MOMENTARILY connecting a 1.5V AAA battery across the ammeter to see that it pegs upscale with one polarity and downscale with the opposite polarity...