correct temp sending unit 70 Dart 318

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str12-340

str12-340

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1970 Dart 318, new stock wiring, standard dash (not Rallye) with gauge. Just replaced the entire cooling system. Replaced Temp sending unit with OER 2426458 from Summit. Gauge hardly registers when temp gun says engine is at 180degrees. Gauge does react but just a bit over the line above "C", but it does move. Everything seems to be functioning properly in the cooling system but the temp gauge. In looking for a replacement for the OER unit I see ECH TS6178 from NAPA and Standard TS-17 elsewhere. What is the current wisdom on the best unit to use?
 
str12-340 said:
1970 Dart 318, new stock wiring, standard dash (not Rallye) with gauge. Just replaced the entire cooling system. Replaced Temp sending unit with OER 2426458 from Summit. Gauge hardly registers when temp gun says engine is at 180degrees. Gauge does react but just a bit over the line above "C", but it does move. Everything seems to be functioning properly in the cooling system but the temp gauge. In looking for a replacement for the OER unit I see ECH TS6178 from NAPA and Standard TS-17 elsewhere. What is the current wisdom on the best unit to use?
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One thing I want to mention is that new parts frequently are faulty right out of the box. The new temperature switch could be faulty. I call it a switch because that is basically what it is. Current (about 5 volts) goes from the Instrument Voltage Regulator (IVR), through the temperature gauge's bi-metallic coil and to the temperature switch. If the engine is cold, the resistor in the switch will not allow any current to flow through it to the grounded engine. With no current flowing through it, the bi-metallic coil in the temp gauge will not warm up, and there will be no needle movement. As the engine gradually warms up, the switch will gradually allow current to flow through it, the current will flow through the bi-metallic coil in the temp gauge, that coil will heat up and expand, and the needle will move. The warmer the engine is, more current will flow, and the gauge's needle will move more. If the engine gets really hot, 5 full volts will flow through the switch and the needle will peg.

Here is what I would do. Check the IVR by turning the ignition switch to the on position, pulling the wire off of the temp switch and checking the voltage coming out of the wire. It should be about 5 volts, and it may be pulsating a bit. I know the IVR in my 69 Barracuda pulses, but the 70 might not. If you do have current, then the IVR is probably working OK. If you do not, it could be the IVR, or a faulty temperature not allowing current to flow through it. If your other gauges are working, it is not the IVR. Now check the temp gauge. Then, using a jumper wire, momentarily ground the wire that attaches to the temp sensor switch to a known good ground and have a helper tell you if the temp needle is moving. I'd use a helper, because I don't want to leave the wire grounded any longer than needed. if the gauge works, I would assume that the switch was bad.
 
str12-340 said:
1970 Dart 318, new stock wiring, standard dash (not Rallye) with gauge. Just replaced the entire cooling system. Replaced Temp sending unit with OER 2426458 from Summit. Gauge hardly registers when temp gun says engine is at 180degrees. Gauge does react but just a bit over the line above "C", but it does move. Everything seems to be functioning properly in the cooling system but the temp gauge. In looking for a replacement for the OER unit I see ECH TS6178 from NAPA and Standard TS-17 elsewhere. What is the current wisdom on the best unit to use?
Click to expand...
Whatever sender is in my 70 318 Swinger, the gauge barely regesters as well. It does get to hot because it did overheat once. (bad cap)
 
This is most likely the issue for you both.

I would buy the "solidstate" IVR they recommend as the far superior realtime engineering IVR has an output that mimics that of the electromechanical rather than a constant 5-6 volts if the cheap "solidstate" IVRs

Screenshot_20250517-075933.png


The replacement gauges function differently than the thermoelectric gauges that came with our cars.
You can get a stock used gauge cluster for less than one repo gauge with a decal on its face and no headaches.

Not to mention you get 2 gauges temp and fuel. Take the faceplate off each and now you have two working gauges to use on either temp or fuel. The guts inside are the same.

There are some tattle tails to look for when buying a cluster, if you go down that route pm me.
 
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That is part of what is weird here - the gas gauge works perfectly, even accurately. It is the original gauge and original tank sending unit, so I am loathe to change anything that would throw the gas gauge off.
 
str12-340 said:
That is part of what is weird here - the gas gauge works perfectly, even accurately. It is the original gauge and original tank sending unit, so I am loathe to change anything that would throw the gas gauge off.
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Mine too. Stock tank, sender, wiring, and gauge. I would bet an incorrect or defective sender or the po sealed the threads with teflon tape and it's not grounding properly. (just guessing there)
 
TS17 is what i use. Altho i run aftermarket Autometer gauge. Also dbl chk your temp gun. I have a cheap one and it's like 20* off.
 
Find a good original sender, I haven't had any luck with new ones.
 
I just ordered a new sender from NAPA: ECH TS6178

Supposed to show up Tuesday. I'll let you know if this solves the issue. The picture shows a sender that is different in small visible details, so I hope that it is a different manufacturer. I have used Teflon tape to seal senders for 40 years and never had problems like this. Some companies even sell their senders with tape in place on the unit.

As suggested I got the wife to sit in the drivers seat while I grounded the sending unit wire and the gauge immediately headed across the scale. Ungrounded the jumper before it got to the end of the "normal" bracketed range to keep from damaging the gauge.
 
str12-340 said:
I just ordered a new sender from NAPA: ECH TS6178

Supposed to show up Tuesday. I'll let you know if this solves the issue. The picture shows a sender that is different in visible details, so I hope that it is a different manufacturer. I have used Teflon tape to seal senders for 40nyears and never had problems like this. Some companies even sell their senders with tape in place on the unit.

As suggested I got the wife to sit in the drivers seat while I grounded the sending unit wire and the gauge immediately headed across the scale. Ungrounded the jumper before it got to the end of the "normal" bracketed range to keep from damaging the gauge.
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Ya, let us know if it works the way it should. Thanks
 
I'm presuming that if the IVR were bad, the gas gauge wouldn't work either since they both go through the same unit.
 
str12-340 said:
I'm presuming that if the IVR were bad, the gas gauge wouldn't work either since they both go through the same unit
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Yes but if the temp gauge is supposed to have a constant voltage rather than a pulsed voltage, then the IVR is the issue. The OEM fuel gauge can handle constant voltage non-issue.
 
Since I've owned this car since the early 1980s, I know that neither the IVR or the gauge has ever been replaced.

I have dealt with the incompatibility of the new repop gauges and the two types of IVR on one of my other Darts, so am aware of that.
 
Joy, Joy, Jubilation, Celebration!!!!!!
I installed the Echlin temp sending unit from NAPA and the temp gauge works perfectly.

The part# is: ECH TS6178

For those who discussed the advisability of various sealing methods - this unit came already taped from Echlin with sealing tape.

Toolmanmike, I hope this fix works for you as well - if you try it please let us know!

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