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Oil and temp sending unit measurements

74Runneer

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I've got a 74 road runner with a 318 in it and I can't get my temp and oil gauges to work. I sent my rallye gauge cluster to Bob's speedometer to get them redone and then installed it and my gas gauge works now but my oil, temp, and batt don't. I installed new oil and temp sending units and made sure that they are the sending units, not the switches. These sending units are the resistance kind, right? So I should be able to measure the resistance across the the unit and watch it vary as temp/pressure varies.

My question: Can someone measure the resistance across their electric sending units and tell me how you did it and what values you get?

Thanks!
 
The measurement for both the the oil and temp should be around 72 ohms to ground when cold and no pressure. The values for the fuel,temp and oil gauges are all the same 72 ohms for low scale 23.5 for middle scale and 10 for high scale. This applies to all three gauges.
 
It might also be a good idea to inspect all your wires. I had the same problem with my 73 Charger, and found the wire to be pinched in two.
 
I just hooked up a mechanical oil gauge to my 74 Roadrunner, and it shows about 45 PSI of oil at idle when cold, about 25 PSI at idle when the engine is hot, but the Oil Pressure gauge on the Rallye cluster shows the same reading regardless. It gets to the first line and stays there, which I guess is where it needs to be as per the sender, but it's essentially acting like an idiot light.
 
I just hooked up a mechanical oil gauge to my 74 Roadrunner, and it shows about 45 PSI of oil at idle when cold, about 25 PSI at idle when the engine is hot, but the Oil Pressure gauge on the Rallye cluster shows the same reading regardless. It gets to the first line and stays there, which I guess is where it needs to be as per the sender, but it's essentially acting like an idiot light.

Bruzilla,

Can you measure the resistance from where the wire connects to ground? I'm trying to get a resistance reading from both the oil and temp senders but I can't get any. Makes me think I'm measuring it wrong.
 
i gave the values in post #2 the values are to ground and where the wire attaches. if your not getting a value you have bad senders (new ones or not) or a grounding issue
 
I'm at napa right now trying to test these sending units. What am I doing wrong? I'm trying to measure the resistance across the sending unit. Even when I apply pressure to the hose, i get a reading of 1 .0 which I believe means open circuit. I did this test for multiple sending units and all of them behaved the same. We also made sure it was the gauge one, not the switch. What am I doing wrong? How am I supposed to get the 10-72 ohms?

getPart
 
Update: I returned the sending unit that I got from napa (3rd one) and went to O'Reillys and bought a mechanical oil gauge and another oil sending unit (4th one). The mechanical gauge was reading about 52 psi so I switched over to the electric oil sending unit and it works... it reads at the first tick mark which is like at the 1/3 full mark. I've read that this is normal. I know it's more of a dummy light but I think I'm just going to use that instead of the mechanical one. I like the original look. My temp gauge works and reads just over the tick mark by 'C' at about 175*-180*. From what ive read, I believe this is normal too.

Moral of the story, dont trust "new" probably Chinese parts at auto stores. It took me 4 times before I got a working one.
 
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