hotrod swinger
Well-Known Member
Sorry, I wasn’t clear, I was talking about the solid state instrument voltage regulator.
Edited: another fuel/temp gauge thread, but turns out the harness is melted together
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Sorry, I wasn’t clear, I was talking about the solid state instrument voltage regulator.
I have seen them available at autoparts stores.
Classic has them
IVR607 - 1966-74 Mopar A, B & E-Body Instrument Voltage Regulator
RT Engineering has the solid state one.
It is expensive but I like the protections it offers.
RTE limiter - rte
If you buy an IVR and the underside looks like this with the little screw on the left just above the left terminal it is a mechanical type IVR
Classic has them
IVR607 - 1966-74 Mopar A, B & E-Body Instrument Voltage Regulator
RT Engineering has the solid state one.
It is expensive but I like the protections it offers.
RTE limiter - rte
If you buy an IVR and the underside looks like this with the little screw on the left just above the left terminal it is a mechanical type IVR
67Dart273
Well-Known Member
Beat you too it!
My fuel gauge had a similar problem. Between the tank nipple and the hard line on the fram, there is a jumper wire between the two for continuity. Mine was knocked off. I cleaned and reattached it, and it cured the problem.
Oil warning lamp operates on 12 volts. Only relation to the thermal gauges is the switched 12 volt source. Earlier models had 2 switched 12 volts to the inst' panel. One for warning lamp(s) and another for the gauge voltage limiter.
But your car's IVR is working. Your quick checks show the temperature and fuel gages seem to work. The resistance from the temp and fuel senders appears to off. Find a temperature sender that is closer to 75 Ohms at room temperature or below. Dana covered the aftermarket fuel sender issues Fuel gauge empty when half full, temp gauge low when engine hot, where do I start?
You can also buy some resistors or a potentiometer fairly cheap and make your own tester.
I have a sender simulator I made to troubleshoot gauge problems. I has switches for empty, 1/2 and full. It also works for temp and oil gauges. You can borrow it if you want.
Aftermarket temp senders are very poor quality. Check the resistance out of the box before you install.
Operating temperature is not always the center of the gage.
At this time of year in most of the US and Canada, be lucky if the thermostat opens fully afte the car has been idling or doodling around. Something around 180 to 190* F.
After a long drive uphill, or a couple hours at freeway speeds, might get that up to 200 to 210*F.
In hot weather it will run a bit hotter.
Anything between 170 and 230 is normal warmed up temperature as long as it makes sense based on conditions. Immedietely after shutting the engine off, coolant temperature will rise a bit.
This is from a 1975 Owners manual. Get a '73 and it will say about the same thing.
hotrod swinger
Well-Known Member
Mine is running at the line where your arrow points 170
hotrod swinger
Well-Known Member
Just crawled under the car. I have a ground strap in place. But it may need to be cleaned up to ensure good contact right?
It never hurts to make sure you have good connections, but that won’t solve your aftermarket fuel gauge problems.
The basic issue is that the A body gas tank has a big scoop out of it on about the top half to clear the spare tire well. Since the top half of the tank holds a lot less gas, the fuel level drops a lot faster in the tank. The factory senders are non linear to account for the tank shape. The float arms are also much longer than the aftermarket.
The aftermarket senders a a linear design and do not account for the tank shape, so they don’t work properly. The float arms are much shorter as well. The gauge drops fast from full, because there is not much fuel in the top half of the tank. The float arm length also influences this.
Below are a couple of charts I pirated from somebody else on the forum to illustrate this.
hotrod swinger
Well-Known Member
Thanks for that information. This is exactly how my gauge is working right now, and honestly I can live with that. After all, I’m just trying to avoid running out of gas, right? Maybe someday I will swap an OEM sender.
This is where I am running right now:
Maybe it will read higher in the summer. If this is not considered a “too low” reading, and I can be assured the gauge will spike if my temperature increases, again I can live with this. I tested resistance at the sender, and I’m confident the sender is functioning properly.
Both gauges havE a regulated source. The IVR is nothing but a flasher. 1 sec on, 1 sec off. Averaging to half the supply voltage. Slow responding heated spring wire gauges are not “meters” and respond slow Put a LM7806 three leg voltage regulator in place of the “5v regulator flasher”
I’ve done it , works great.
I’ve done it , works great.
Having been a perfectionist most of my life, I have found that if I can curb that a bit, I have a lot more fun driving them than working on them all the time fixing something that might not really need fixed. It’s an ongoing struggle for me…..
hotrod swinger
Well-Known Member
I hear that man.
I was running a precise aftermarket gauge cluster, but I wanted to bring my factory gauge cluster back to life and use that. I don’t need precision, just a warning if my fuel is low, temp is high, or oil pressure is low.
At this point, I think for the most part I’ve achieved my objectives. My brake warning lamp works. My oil warning light is now operational. My cluster illumination lights are all working, as well as my turn signals and high beam indicator.
My fuel gauge goes from full to half full quickly, and then goes from half to empty slowly and reads empty with 12 litres in the tank. I can live with that. Someday I’ll install an OEM sender, or maybe not.
My instrument voltage regulator seems to be working correctly. I understand I have to watch for pegging fuel and temp gauges and shut off the car and remove the fuse immediately if that happens.
The only thing now I’m not really sure about is that low temperature reading, I would have expected it to be closer to the middle but again if I’m simply watching it for a spike, I can live with that.
hotrod swinger
Well-Known Member
Would it be sensible to try a new temperature sender?
I just had the gauge cluster out and I’m pretty sure all of my connections are good.
I just had the gauge cluster out and I’m pretty sure all of my connections are good.
New sender is pretty easy & cheap. See if you can get a Mopar one. Measure it before you put it in. I have had them bad out of the box, and also fail the first time they warm up, or maybe they were damaged installing. Seems like I have bought a bunch of them. They seem to be pretty crappy quality, like most Chinese stuff.
hotrod swinger
Well-Known Member
Do temperature senders vary from year to year? I am running a 1978 360 in my 1973 Swinger.
Also, I just left the sender installed that came with the engine before I rebuilt it. I actually have no idea of it’s origin.
I think I still have the sender that was installed in the original 318. Maybe I should swap that in?
Also, I just left the sender installed that came with the engine before I rebuilt it. I actually have no idea of it’s origin.
I think I still have the sender that was installed in the original 318. Maybe I should swap that in?
That could be thermostat stuck open. Have you checked actual water temp?
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hotrod swinger
Well-Known Member
Yes, I have recently ran a mechanical water gauge and checked with an infrared pointer. I know the engine runs at 180-190
hotrod swinger
Well-Known Member
This is where my needle is at operating temperature with resistance at 24:
Am I wasting my time changing the sender?
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hotrod swinger
Well-Known Member
Just did some resistance checks:
135 F is 66 ohms
142 F is 56 ohms
160 F is 42 ohms
170 F is 35 ohms
175 F is 32 ohms
180 F is 30 ohms
135 F is 66 ohms
142 F is 56 ohms
160 F is 42 ohms
170 F is 35 ohms
175 F is 32 ohms
180 F is 30 ohms
67Dart273
Well-Known Member
The needle should be mid scale at that resistance BUT "is the resistance" actually appearing at the gauge stud?
The path is engine block and ground, sender, sender wire end terminal..........through the bulkhead connector terminal............to the cluster harness connector.........the pc board pin.........to the pc board trace.........to the gauge stud and nut. Any of those points could be a poor connection, OR the gauge wrong, or not getting proper power from "the other end" of the loop.
If you are sure you are correct in your measurements, and can check it clear back to the gauge, then I'd eliminate the sender and sender wiring.
This is why I often talk about "thinking of it as an end to end system" (instead of one or two parts) and think/ draw/ keep in mind the "circuit path"
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