Temperature gauge does not work on my 1970 340 Duster ?

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And thats why placing the sender wire directly to ground doesn't really check anything but the wire. Zero ohms resistance will get results that within the normal 80-10 range will not. A cooked gauge will be way out of calibration but in that case the needle wouldn't go all the way to home at off either.
My solid state regulator examples are of those housed inside fuel gauges. Those must be a adaptation of universal type regulator. The RTE unit may be a bit pricey but it is a plug and play solution.
Regardless what route you take ADD A CHASSIS GROUND WIRE TO THE INST' PANEL. The factories daisy chain of a ground path ( through parts and mounting hardware ) is unreliable and too easily degraded or broken. The T805 solid state bit used in most of the replacement regulators will pass full 12 volts when not grounded.
 
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72demon340rag said:
update on the temp gauge ghost. I pulled the sensor and dropped it in a can of 212º water. It registers about 120º on the gauge. Ohms at .105, so either the gauge is out of calibration (not too likely) or the voltage step down is not outputting 5 volts. (40 year old part) I'm going to get a solid state converter and fingers crossed. Stay tuned.
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Back at it. I installed the solid state 5 volt limiter, running a dedicated ground to the 5v limiter, Still no temp. The RTE limiter is great and they sent along a resistor to verify the accuracy of the gauge. When I use the resistor inline on the temp sending unit lead, it reads full HOT, Not pegged max like when I do the direct ground method so gauge and wiring are working properly. I'm going to try sending unit #3 just in case Classic Industries sold me 2 bad units. Since I am not running the stock manifold, I'm going look for a longer length to see if perhaps the manifold design is not clearing air from the system. I'm out of ideas and ready to run it without the gauge reading until i can get this thing to an exorcist.
 
I have had trouble with aftermarket sensors a lot. I have a trans am that I wound up buying the sensors from a GM dealer because I couldn’t get multiple sensors to work right. The way the cooling fans work is pretty marginal, so the sensors have to be pretty accurate. Works fine with the OEM sensors.

My temp gauge isn’t working & I built a simulator box and found my wiring and gauge were ok. My temp sender reads about 6500 ohms. I could have swore I checked it before I installed it. I have a post on it in the electrical section.

I’ll send it to you if you want, just pm me your address. It fits in a small flat rate box.

DB4D10E0-B3ED-4B96-9A3F-AF7790D26E6A.jpeg
 
Mike69cuda said:
I have had trouble with aftermarket sensors a lot. I have a trans am that I wound up buying the sensors from a GM dealer because I couldn’t get multiple sensors to work right. The way the cooling fans work is pretty marginal, so the sensors have to be pretty accurate. Works fine with the OEM sensors.

My temp gauge isn’t working & I built a simulator box and found my wiring and gauge were ok. My temp sender reads about 6500 ohms. I could have swore I checked it before I installed it. I have a post on it in the electrical section.

I’ll send it to you if you want, just pm me your address. It fits in a small flat rate box.

View attachment 1715282247
Click to expand...

Wow, thanks for the super offer, not sure if is necessary though.
Please heck my logic on this;
The guy who I bought my voltage limiter from sent a resistor along with it so could verify my gauge was working. I'm not sure the impedance of the resistor, but it was supposed to read "F" (full) when used in placement of the sending unit, as oppose to pegged out when I did a direct ground of the lead wire. It did just that.
Everything I could find online only shows there is only one sending unit for that year, so i have the right part number at least. bought both from classic industries and i was marked as Genuine Chrysler part. When I check the ohms while it is heating up, it is moving: wether it is accurate nobody guess. When I remove the sending unit and dropped it into a coffe cup of boiling water, it registered about midway so I assume it is working, accurate, who knows. it cools down a bit from the kitchen to the shop. My only conclusion, be it logical or 'shade tree', is that there is something wrong with the installation. Dedicated ground was added to eliminate that discussion. I have seen signs of a slight intake manifold leak (bubbles at the top) I can only think that I am getting exhaust pushed into the cooling system somehow. My thinking would be that if that was the case I'd have a long list of the problems that would dwarf the temp gauge not working but I'm grasping at long shots on this one. I'm planning on pulling the engine when i paint and rework the seals on the engine especially the intake manifold so I'm hoping I find something that looks out of the ordinary.
 
I haven’t gone back and read the thread again, but is the engine temp really low? I bought one of those infrared thermometer things at harbor freight and t works really well. It was pretty cheap. I think they sell them at Lowe’s now too. You can even take your kids temperature with it by shining it in their ear. Just like a real doctor, almost!
 
Make sure you have the right temp sending unit. I had this problem on my 67 Barracuda. The parts store sold me the temp sending unit for the idiot light not the gauge.
 
After the first few posts in the first page it would have seemed the gauge and wring were all fine.

4 pages later could I ask you to post a picture of the sender and more importantly the installation of the sender in the manifold.
 
And do you have a thermostat installed?
 
On a rare chance did you try a jumper from sender base to battery ground? Im assuming its good as you tested wire with the resistor. Grounded resistor to manifold?
Sender not tight enough and not getting ground through sealant,?
 
my temp and amp gauges were iffy at best, oil pressure was OK but not that useful with just HI /LO. Felt like I could sort this 'till the cows came home and still have 50 year old worn junk that wasn't great when new. Basic trio of aftermarket gauges was best option for me and easy install. no regrets. These type worked OK for me. I appreciate you may want to keep it stock and get it all working. fwiw

Equus 6200: Trio Gauge Set 2" Diameter | JEGS
 
Mike69cuda said:
I haven’t gone back and read the thread again, but is the engine temp really low? I bought one of those infrared thermometer things at harbor freight and t works really well. It was pretty cheap. I think they sell them at Lowe’s now too. You can even take your kids temperature with it by shining it in their ear. Just like a real doctor, almost!
Click to expand...
The engine is running at normal temperatures. It is pegged out on the 'cold' setting the whole time.
 
Tooljunkie said:
On a rare chance did you try a jumper from sender base to battery ground? Im assuming its good as you tested wire with the resistor. Grounded resistor to manifold?
Sender not tight enough and not getting ground through sealant,?
Click to expand...
Yes i did. I made a direct ground from the neg terminal on the battery to the sending unit body in case there waste excess teflon tape. nothing.
 
RedFish said:
And thats why placing the sender wire directly to ground doesn't really check anything but the wire. Zero ohms resistance will get results that within the normal 80-10 range will not. A cooked gauge will be way out of calibration but in that case the needle wouldn't go all the way to home at off either.
My solid state regulator examples are of those housed inside fuel gauges. Those must be a adaptation of universal type regulator. The RTE unit may be a bit pricey but it is a plug and play solution.
Regardless what route you take ADD A CHASSIS GROUND WIRE TO THE INST' PANEL. The factories daisy chain of a ground path ( through parts and mounting hardware ) is unreliable and too easily degraded or broken. The T805 solid state bit used in most of the replacement regulators will pass full 12 volts when not grounded.
Click to expand...
Sorry for asking 2 years later, but are you saying that if the guage doesnt go all the way hot when shorting the sender wire to ground, the guage is bad? Mine goes to about 3/4 of the way to hot then stops.
 
Tylan said:
Sorry for asking 2 years later, but are you saying that if the gauge doesn't go all the way hot when shorting the sender wire to ground, the gauge is bad? Mine goes to about 3/4 of the way to hot then stops.
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either the IVR is week, the gauge needs calibration, or there is some resistance in the sending wire path. (a bad ground from the engine to the chassis could do that, assuming you grounded the sender wire to the engine)
 
Dana67Dart said:
either the IVR is week, the gauge needs calibration, or there is some resistance in the sending wire path. (a bad ground from the engine to the chassis could do that, assuming you grounded the sender wire to the engine)
Click to expand...
So far I have replaced the IVR with a new solid state one and replaced the sensor itself. As for testing the guage, I've grounded from the sender wire to the chassis and directly to the negative battery terminal, both giving the same results. The furthest I've gone for testing the sender wire was putting on lead on the sensor connector and the other lead on the guage wire within the instrument cluster connector, but made the mistake of only listening to the continuity beep function my multimeter has, I'll have to check for actual resistance.
 
If you short the sender wire directly to ground, that is zero resistance. Gauge needle should travel to it max position. This condition can overheat and damage a gauge. In some panels a part of the panel assembly can hinder needle movement. It is not normal for a gauge to need re calibration. If the panel hasn't been apart, I'll guess you need to replace the gauge.
 
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