Chevy Tri Five Forum banner
Cancel

56 bel air temperature gage

646 Views 33 Replies 11 Participants Last post by  55 Tony, 
yellowtr3
all original instruments.
when i took delivery of my 56 i noticed that the temp gage would stay at cold and then when the motor warmed up it would jump to boiling. no inbetweenie.
used a laser temp gage and found the top of radiator was running around 180. so it was not boiling.
also drove the car for some miles without problems.
bought a new sender unit from one of the suppliers.
same thing happening.
you smart folks here were able to tell me that the sender unit is for 56 only. just a one year thing and other years will not work.
one of you nice people sold me 2 used 56 sender units and checked them before sending them to me. i trust in you and dont think its your sender unit anymore. heck, iv been through 4 of them now.
so..............
tried looking at the wiring diagram in the shop manual.
looks like the wire from the sender unit goes straight to the gage.
the diagram does not show where the power comes from, so im going to assume the power supply goes to the gage and then to the sender unit and is going to ground at the sender?
as the gage moves it appears im getting power to the gage?
does the gage run on 12volts or is there a step down before the power gets to the gage?
any other thoughts on what my problem is?

thanks
Frank
Reply
Save
Like
1 - 20 of 34 Posts
Shadetree55
yellowtr3 said:
all original instruments.
when i took delivery of my 56 i noticed that the temp gage would stay at cold and then when the motor warmed up it would jump to boiling. no inbetweenie.
used a laser temp gage and found the top of radiator was running around 180. so it was not boiling.
also drove the car for some miles without problems.
bought a new sender unit from one of the suppliers.
same thing happening.
you smart folks here were able to tell me that the sender unit is for 56 only. just a one year thing and other years will not work.
one of you nice people sold me 2 used 56 sender units and checked them before sending them to me. i trust in you and dont think its your sender unit anymore. heck, iv been through 4 of them now.
so..............
tried looking at the wiring diagram in the shop manual.
looks like the wire from the sender unit goes straight to the gage.
the diagram does not show where the power comes from, so im going to assume the power supply goes to the gage and then to the sender unit and is going to ground at the sender?
as the gage moves it appears im getting power to the gage?
does the gage run on 12volts or is there a step down before the power gets to the gage?
any other thoughts on what my problem is?

thanks
Frank
Click to expand...
12 volts keyed ignition to the gauge. have you tested it? cold engine key on it should read cold. leave key on and unplug wire on sender and ground it. The gauge should make a slow sweep all the way to hot and return to cold when you plug it back up
Reply
Save
Like
Tropturq
The temperature gauge has two electrical connectors on it. One is for a pink wire and this is for 12 VDC accessory power, there is no fuse. The other green wire on the gauge runs through the firewall and directly to the sender. The sender puts out a variable ground signal dependent on temperature. As you know, the sender itself is a one year only 1956 part, and no other generic sender will give a correct reading. Don't be convinced that the problem could not also be a bad gauge, even though it moves. The gauges will not last forever. If yours is original, it is now 67 years old. You may want to replace it. Here is a link to a correct sender. It will work properly, and is well worth the money.
www.lectriclimited.com

Temperature Sending Unit

-original 1/2 x 14 N.P.T.F.-, (correct resistance and connection, produces accurate gauge display)
www.lectriclimited.com www.lectriclimited.com
Here is a link to a sender wire repair kit if your wiring is old and "crusty".
www.ebay.com

1956 1957 1958-& up CHEVY TEMPERATURE SENDER WIRE REPAIR KIT ** USA MADE ** | eBay

Find many great new & used options and get the best deals for 1956 1957 1958-& up CHEVY TEMPERATURE SENDER WIRE REPAIR KIT ** USA MADE ** at the best online prices at eBay! Free shipping for many products!
www.ebay.com
Here is a link to a temperature gauge that will work for you. I replaced mine about two years ago with this same gauge. It works perfectly with a correct 1956 sender.
www.ebay.com

56 Chevy Temperature Gauge *NEW* 1956 Chevrolet | eBay

Find many great new & used options and get the best deals for 56 Chevy Temperature Gauge *NEW* 1956 Chevrolet at the best online prices at eBay! Free shipping for many products!
www.ebay.com

There is also a NOS 1956 temperature gauge currently listed on E-Bay. It is an auction with no buy it now option.
www.ebay.com

VINTAGE 1956 CHEVY CAR NOS GM ELECTRIC TEMPERATURE GAUGE AC# 1513378 NR | eBay

Find many great new & used options and get the best deals for VINTAGE 1956 CHEVY CAR NOS GM ELECTRIC TEMPERATURE GAUGE AC# 1513378 NR at the best online prices at eBay! Free shipping for many products!
www.ebay.com

Steve
See less See more
Reply
Save
Like
  • Helpful
  • Like
Reactions: 3
stoveboltgeek
Tropturq said:
The temperature gauge has two electrical connectors on it. One is for a pink wire and this is for 12 VDC accessory power, there is no fuse. The other green wire on the gauge runs through the firewall and directly to the sender. The sender puts out a variable ground signal dependent on temperature.
Steve
Click to expand...
Technically, the sensor provides a varying resistance to ground as a function of temperature. (I wouldn't call it a variable ground signal per se)

To be extra-technical, the sensor is a thermistor - a resistor whose resistance varies according to temperature. (Thermal + resistor = thermistor.)
Reply
Save
Like
  • Like
  • Helpful
Reactions: 2
angs1957
Do those checks mentioned above, sounds like either the sender wire is grounding or the cluster gauge is faulty, providing you have the correct sender.
Reply
Save
Like
Pops @ Tri-5.com
I would start by replacing the sender with the CORRECT one: Temperature Sending Unit
Reply
Save
Like
yellowtr3
im pretty sure we are all in with the sender unit.
the one on the car when i got it worked the way i described above.
on the advice you you good people i bought the sender from the links above. same problem.
a nice guy on here sold me 2 used 56 only senders. same problem.
so ill go out on a limb and say its not the sender.
funny way for the gage to go bad.
do you guys know what the cold and hot resistance should be, if i throw a ohm meter across it?
touching the wire at the sender to ground sends the gage to all the way right hot. have not looked at shadetree55' suggestion. ill get to that this long weekend.
you guys are the best
thanks
Frank
See less See more
Reply
Save
Like
Tropturq
If you are certain that you have the correct sender, then check the rear connectors of the temperature gauge and make sure that there is no corrosion, and that they are both a snug fit. If the connections are clean and solid, my vote is for a bad gauge.

Steve
Reply
Save
Like
  • Helpful
Reactions: 1
yellowtr3
Tropturq said:
If you are certain that you have the correct sender, then check the rear connectors of the temperature gauge and make sure that there is no corrosion, and that they are both a snug fit. If the connections are clean and solid, my vote is for a bad gauge.

Steve
Click to expand...
im kinda leaning that way also.
Reply
Save
Like
hotrodg726
also chec to see that the whole cluster grounds to the dash good. I usually make a ground wire to go from the back of the speedometer assy to the body.
Reply
Save
Like
  • Like
  • Helpful
Reactions: 4
yellowtr3
hotrodg726 said:
also chec to see that the whole cluster grounds to the dash good. I usually make a ground wire to go from the back of the speedometer assy to the body.
Click to expand...
good idea.
Reply
Save
Like
angs1957
FYI when you replaced the sending unit did you screw it straight in or did you use any sealant tape or sealant. I hope you screwed it straight in do not put any tape/sealant or it will insulate the sender from giving you a reading.

I found this old thread with information directly to your questions;
www.trifive.com

56 chev Temp guage not working properly

Hello, I have already read several of the old questions regarding the temp gauge for a 56 chev. I still cannot figure out if the gauge oor the sending unit is bad, or both. My gauge sits on cold when I start the engine, and then when it is starting to come up to the thermostat opening the...
www.trifive.com www.trifive.com
Reply
Save
Like
  • Like
Reactions: 1
Farm Boy


The temp gauge has two electromagnet coils. Both coils receive 12 volts from the pink wire. The green coil is grounded through the gauge and the red coil is grounded through the temp sender unit. In other words the magnetic field of the green coil is constant and the red coil is variable. The needle is located between the two magnetic fields.

If the green coil isn't working the gauge will be out of balance and peg on hot. Check the continuity of the green coil with a multi meter. The fix could be as simple as cleaning the ground contact.
See less See more
Reply
Save
Like
  • Like
  • Helpful
Reactions: 4
yellowtr3
one last question for now guys.
thanks to TROPTURQ i bought the NOS gage from ebay.
i do not want to pull the dash out for while. car is kinda new to me and i want to get some miles in.
so, when the NOS gage arrives i want to check it before installing later.
looking at this picture what wire goes where? is A to the sender or is B that goes to the sender. ill make a couple jump wires with clips and take power from the battery, the other side ill clip to the sender.
and the housing has to go to ground?
thanks for all the info
See less See more
Reply
Save
Like
Pops @ Tri-5.com
The terminals should be marked on the rear
See less See more
Reply
Save
Like
yellowtr3
Pops @ Tri-5.com said:
The terminals should be marked on the rear
Click to expand...
Pops @ Tri-5.com said:
The terminals should be marked on the rear


there are no markings on the rear.
this is the ebay item i bought.



Click to expand...
See less See more
3
Reply
Save
Like
Farm Boy
Hopefully the new gauge will solve your problem. Before you toss your old gauge in the trash check out this post:
56 Temperature Gauge...How it works
Reply
Save
Like
  • Helpful
Reactions: 1
yellowtr3
Farm Boy said:
Hopefully the new gauge will solve your problem. Before you toss your old gauge in the trash check out this post:
56 Temperature Gauge...How it works
Click to expand...

eureka

thanks
Reply
Save
Like
Pops @ Tri-5.com
As you look at the rear of the gauge, the terminal on the right goes to +12V and the left one goes to the sender.
See less See more
Reply
Save
Like
  • Like
Reactions: 1
tjsdelivery
For a NOS gauge, that gauge looks a bit odd. Hopefully it is for a 56 Chevy.
Reply
Save
Like
1 - 20 of 34 Posts
Chevy Tri Five Forum
A forum community dedicated to 1955, 1956, and 1957 Chevy owners and enthusiasts. Come join the discussion about restoration, engine swaps, reviews, performance, modifications, classifieds, troubleshooting, maintenance, and more! Open to all models including Belair, 210, 150, Sedans, and Nomads.
Full Forum Listing
Explore Our Forums
Chit Chat Area, Anything on your mind goes here. New Member Introductions Stock Chevy Discussion 55-56-57 Project Update Section, Post Project Updates Here Suspension Questions Chassis, Brakes, Shocks, Etc
Top