Can '64 Dart Temp Gauge Be Adjusted?

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Duggie

Duggie

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At thermostat opening, my temp gauge reads just off the bottom mark. I'd like to adjust the needle to be at least on the bottom 1/3 mark. The Factory Service Manual talks of using a factory tool to confirm a low, medium, and high reading on the gauge but then says to replace the gauge if it doesn't read correctly.

Can these gauge needles be adjusted?
 
I wonder if I could heat the sender to higher temps and mark where the needle stops.
 
That factory tool would just be basically a rheostat that you could use to dial in a certain resistance to check gauge. You could do same somewhat, by removing wire at sender and grounding it, with key on. Gauge should go all the way high or low. Then maybe use a high impedance (old)l test light, or an old parking light bulb and socket assembly, and run it in series with sender wire to ground, and look for change in gauge reading. It obviously would help if you knew resistance range of gauge, and then measure resistance of checking device for accuracy. You may just have a bad sending unit or engine temp isn't getting as high as you think, or high resistance in circuit ( bulkhead connector).
 
First thing you do is check the gauge for somewhat accuracy using test resistors. This has been documented hundreds of times on this forum

c-3826-jpg-jpg.jpg


There are several avenues of trouble you must check

1...IS THE engine actually operating at the temp you THINK it is? You need to devise ways of checking that, whether a cooking thermometer down the rad. cap, or an infra-red tool or whatever

2...IS THE gauge accurate?

3...IS THERE any wiring problems such as a loose connection

4...IS THE voltage limiter/ IVR/ gauge regulator working properly, AKA outputting the proper voltage

5...ARE THE other gauges working properly? I believe you will find the IVR is in the fuel gauge on your car, and supplies all three gauges, temp, oil, and fuel. So check them with the same test resistors shown in the photo above.
 
Duggie said:
At thermostat opening, my temp gauge reads just off the bottom mark. I'd like to adjust the needle to be at least on the bottom 1/3 mark. The Factory Service Manual talks of using a factory tool to confirm a low, medium, and high reading on the gauge but then says to replace the gauge if it doesn't read correctly.

Can these gauge needles be adjusted?
Click to expand...
Is the sender correct? And is the gauge voltage limiter working, that's the lil metal box that plugs into the cluster with the noise/static filter , looks like a one wire capcitor. How's the fuel gauge accuracy?
 
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I second Moparofficial, make sure you have the sending unit for the gauge and not the idiot light.
 
I just said yesterday that I learned while working on the clutch that just because it was there when I bought the car, doesn't mean it supposed to be there or done right.

I'll check that shinny, new looking sending unit first, Thanks!
 
You need nearly zero resistance between the body of the sender and engine block and neg' battery post. Too much teflon tape on the senders threads, etc,, can increase resistance.
A better guess... the gauge voltage limiter is the problem, your fuel gauge reads low also although you dont know it. In most early panels the limiter is inside the fuel gauge or temp gauge. that gauge has a slither of metal on the back of it that provides a ground for the limiter to the panel. Panel mounting screws link the ground path to dash frame. So its a daisy chain of metal to metal contacts from one end to the other.
Other members have pulled the fuel gauge to clean the contact or simply snugged up all the gauge mounting nuts that have loosened over time. Limiter and gauges work right again.
Adding a dedicated ground wire to the instrument panel insures a good ground there and can even make dash lighting bright again. Hope this helps
 
My gauge reads right at the bottom end of the "operating range" scale most of the time. Infrared temp gun on the T-stat housing reads ~184, and rgw tenp sender read ~181. If I let the car idle for a whille after driving it the gauge goes up about 2 needle widths, and the t-stat housing reads ~190-192.
I'm planning to pull the sender and using my camp stove put it in water as I bring it to a boil, monitoring water temp and marking the gauge reading.
 
RedFish said:
You need nearly zero resistance between the body of the sender and engine block and neg' battery post. Too much teflon tape on the senders threads, etc,, can increase resistance.
A better guess... the gauge voltage limiter is the problem, your fuel gauge reads low also although you dont know it. In most early panels the limiter is inside the fuel gauge or temp gauge. that gauge has a slither of metal on the back of it that provides a ground for the limiter to the panel. Panel mounting screws link the ground path to dash frame. So its a daisy chain of metal to metal contacts from one end to the other.
Other members have pulled the fuel gauge to clean the contact or simply snugged up all the gauge mounting nuts that have loosened over time. Limiter and gauges work right again.
Adding a dedicated ground wire to the instrument panel insures a good ground there and can even make dash lighting bright again. Hope this helps
Click to expand...

Great info! I just filled up the Dart today for the second time since owning it and it took six gallons while reading about 1/3 of a tank on the gauge. It's going to take a little while for this to get to the front burner, but I'll report back after taking your recommended steps.

:thankyou:
 
RedFish said:
You need nearly zero resistance between the body of the sender and engine block and neg' battery post. Too much teflon tape on the senders threads, etc,, can increase resistance.
A better guess... the gauge voltage limiter is the problem, your fuel gauge reads low also although you dont know it. In most early panels the limiter is inside the fuel gauge or temp gauge. that gauge has a slither of metal on the back of it that provides a ground for the limiter to the panel. Panel mounting screws link the ground path to dash frame. So its a daisy chain of metal to metal contacts from one end to the other.
Other members have pulled the fuel gauge to clean the contact or simply snugged up all the gauge mounting nuts that have loosened over time. Limiter and gauges work right again.
Adding a dedicated ground wire to the instrument panel insures a good ground there and can even make dash lighting bright again. Hope this helps
Click to expand...

Duggie said:
Great info! I just filled up the Dart today for the second time since owning it and it took six gallons while reading about 1/3 of a tank on the gauge. It's going to take a little while for this to get to the front burner, but I'll report back after taking your recommended steps.

:thankyou:
Click to expand...
My fuel gauge does the same, and my temp gauge only moves a little bit.
I picked up this IVR replacement info from @RedFish on another gauge post. If cleaning/adding grounds doesn't solve the issue, this might. RTE limiter - rte
 
Some instrument panels are much easier to R&R than others. All of them can be a problem child, one issue after another. To go ahead and clean all electrical contacts, install a solid state regulator, all new bulbs and sockets, add a ground wire, everything we can do while there is my recommendation. If you dont bypass the amp gauge, at least blow any metallic dust off the magnet in it and clean those connections too. I can pull the speedometer cable out this end to clean and lube it but I dont know early A is made the same. Good luck with it.
Duggie said:
Great info! I just filled up the Dart today for the second time since owning it and it took six gallons while reading about 1/3 of a tank on the gauge. It's going to take a little while for this to get to the front burner, but I'll report back after taking your recommended steps.

:thankyou:
Click to expand...
 
BobW said:
My fuel gauge does the same, and my temp gauge only moves a little bit.
I picked up this IVR replacement info from @RedFish on another gauge post. If cleaning/adding grounds doesn't solve the issue, this might. RTE limiter - rte
Click to expand...

Man do I have some reading to do. I don't even know what a limiter is but I bet a solid state one is the way to go! Looks like after I get her aligned and the convertible top hydraulic piston baseplate welded this weekend, I'm pulling the dash.

I read somewhere too about an ammeter work around. Should probably look that up while I'm at it. This is going to be a GREAT little driver. I can see it from here!!
:lol:
 
I built this to check gauges. You can hook it up in place of the oil, temp or gas sender & see if your gauges are working properly. I built it when I was having trouble. Will ship it to you if you promise to return it. Just PM me your address if you want to borrow it.

View attachment 1715595925
 
I adjusted the dash gages, both temperature and fuel, when I had the cluster out in my 64 and 65 A's. I posted w/ photos. Don't ASSume your IVR is bad. It is easy to measure its output voltage on the rear of the dash (large V-shaped copper terminal a fuel gage output bolt slides into). Should be 5 V. Instead, I put an adjustable "voltage limiter" on both clusters. One I bought off ebay for $30, marketed for Mopars. Next pass, I couldn't find it and didn't want to pay $50 for the RTE one. I found a generic Vreg which looked just like the $30 one for ~$7 on Amazon (recall). Works fine. Adjustable is best since that gives you another "knob" to adjust. I had adjust the voltage and add parallel resistors (~20 ohm to rear of cluster) to get the fuel gage to read correct w/ my new sender. That was all the "knobs", but the gages themselves have 2 screwdriver adjustments, so I used those for the temperature gage. One rotates the needle (to set zero?) and the other changes the pivot point (to set gain?). They actually bend the metal, so don't fuss constantly or they will break. Not in the shop manual, so I suspect just something the gage manufacturers did in final inspection. BTW, the only advantage with the RTE IVR I think is that it gives a higher voltage initially after key on, to move the gage needle faster towards center. The OE thermo-mechanical one did that, but perhaps not purposeful so likely no reason to design for that.
 
The factorys' adjustments on the back of the gauge dont bend anything. They rotate the parts where they are braded to bottom of the can. You dont twist a screw driver blade in the slot to move them either. You push the part left or right as far as the little hole will allow.
I never tell anyone these adjustment are there because once moved you might never get close to right again. And that why dealerships service techs were not informed, or advised/instructed to adjust these gauges. If it doesn't respond correct to the 3 point tester... replace it, as stated in starting post.
 
Okay you guys, an update and a question. Update; I tested the IVR and it failed. Greg at RT-ENG is sending me the IVR3 model. I've cleaned up all the contacts on the back of the instrument panel, added a ground wire and am soaking the plastic round pin connector in white vinegar. I also checked and got 0.1 Ohms resistance between the frame point where the panel ground wire will attach and the Neg lug clamp on the battery cable. And just for driving pleasure, I ordered SlantSixDan's recommendation for LED dash bulbs.

The question; RT-ENG instructions shows bending the contact point arm backwards to disable the fuel gauge mounted IVR. In the movies, they never cut the white wire but it looks like I could cut out the white wire in the pic to disable the contact points. The only time I get into trouble is when I think! :BangHead: How do you all disable the gauge mounted IVR?
ivr2.JPG
 
The procedure found online is to remove the gauge screen and bend the little thingy. I'm wondering how you intend to bend those tangs back down again. The sad part is you never needed to open the gauge. All you needed to do was put some electric tape over than piece of metal on the backside of the gauge can to isolate it from ground. the 12 volt supply wire serves nothing but the limiter so take it out of the panel harness connector and route it to the substitute regulator where ever you choose to mount it. It doesn't have to be on the back of the panel.
The stamped tin speedy nuts contact only one thread of a stud, so rusty studs are degraded connections. Good luck with it.
 
RedFish said:
The procedure found online is to remove the gauge screen and bend the little thingy. I'm wondering how you intend to bend those tangs back down again. The sad part is you never needed to open the gauge. All you needed to do was put some electric tape over than piece of metal on the backside of the gauge can to isolate it from ground. the 12 volt supply wire serves nothing but the limiter so take it out of the panel harness connector and route it to the substitute regulator where ever you choose to mount it. It doesn't have to be on the back of the panel.
The stamped tin speedy nuts contact only one thread of a stud, so rusty studs are degraded connections. Good luck with it.
Click to expand...

Didn't see how to take the screen off on my '64, so I went in the back of the can. I can bend the tabs back down with my smallest needle nose plyers and my BFH:D

So to recap, I insulate the back of the fuel gauge can from the panel housing, replace the cheesy tin speedy nuts with real nuts for a better connection, and pull the 12vt lead out of the pin connector to wire the new regulator.

Pardon the redundancy. Sleep deprived and this decafe' coffee isn't cutting it!:eek:
 
Duggie said:
Didn't see how to take the screen off on my '64, so I went in the back of the can. I can bend the tabs back down with my smallest needle nose plyers and my BFH:D

So to recap, I insulate the back of the fuel gauge can from the panel housing, replace the cheesy tin speedy nuts with real nuts for a better connection, and pull the 12vt lead out of the pin connector to wire the new regulator.
Pardon the redundancy. Sleep deprived and this decafe' coffee isn't cutting it!:eek:
Click to expand...

The screen is either crimped onto the rim of the can or held with 2 small brads in rectangular ears on the edge of the can. Either type is pretty easy to open (if/when necessary).
You could just use a wire brush in a dremel to clean away the rust. Hardware will be 10-32 hex nuts and internal toothed washers just like those on the amp gauge. Home Depot has them in small orange plastic packages hanging on a wall. Yellow packages are stainless and cost more. Use them on top of the speedy nut where you'll place a ring terminal of the 5 volt wire from your regulator, if you dont use them everywhere.
I've ran into a few of these studs that a hex nut would not go on. 3 or 4 in the course of 8 years and few hundred gauges. Evidently there was no need for tight tolerance or quality control since they weren't going to get a real nut anyway. Also ran across a few that were so rusted I had to cut the speedy nut off of them. Running a die over the threads to clean them up is tedious labor. The board is very easily broken.
 
RedFish said:
You need nearly zero resistance between the body of the sender and engine block and neg' battery post. Too much teflon tape on the senders threads, etc,, can increase resistance.
A better guess... the gauge voltage limiter is the problem, your fuel gauge reads low also although you dont know it. In most early panels the limiter is inside the fuel gauge or temp gauge. that gauge has a slither of metal on the back of it that provides a ground for the limiter to the panel. Panel mounting screws link the ground path to dash frame. So its a daisy chain of metal to metal contacts from one end to the other.
Other members have pulled the fuel gauge to clean the contact or simply snugged up all the gauge mounting nuts that have loosened over time. Limiter and gauges work right again.
Adding a dedicated ground wire to the instrument panel insures a good ground there and can even make dash lighting bright again. Hope this helps
Click to expand...

BobW said:
My gauge reads right at the bottom end of the "operating range" scale most of the time. Infrared temp gun on the T-stat housing reads ~184, and rgw tenp sender read ~181. If I let the car idle for a whille after driving it the gauge goes up about 2 needle widths, and the t-stat housing reads ~190-192.
I'm planning to pull the sender and using my camp stove put it in water as I bring it to a boil, monitoring water temp and marking the gauge reading.
Click to expand...
Yesterday I drained the coolant to flush the system and replace the antifreeze. While the system was empty I removed the temp sender and hung it in a pot of water over my camp stove. I also ran a ground wire from the battery to the sender body. Used a cooking thermometer to read the water temps
The marks on the tape indicate 170*, 180*, 190* 200* and 210*. They're a little indistinct, my wife has Parkinson's.
If you were to look where the needle would intersect with the temp gauge scale, I consistently run at the first line "operating range", which correlates with my 180* mark. I get the same 180* on the thermostat housing using an infrared thermometer. The highest I've seen in stop & go traffic on a 95* day is around the 190* mark.
Now I have satisfied that the sender & gauge work and seem to be fairly linear, but appear to be about 1/2 the scale of the gauge.
Does this indicate, or be consistant with, a bad IVR?

Temp1.jpg
 
Bob. Redfish will have a more complete answer but 200 F around the middle of the scale would seem about correct.
These systems operate under pressure. I forgot what the early caps open at, but its something between 11 and 16 psi.
Bottom line is that operating temperatures above 212 F are still normal.
The inside lines probably are meant to indicate the normal operating range, something like 190 to 225 is my guess. Do you have an owner's manual in the glovebox? Might say in there.

I think I took this pic from the owners manual of my '75 Valiant (long gone).
Hot on the gage was 250 F
upload_2020-10-16_14-24-41.png
 
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