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Username Post: coolant temp reading on 1956 truck        (Topic#356867)
Posts: 3

Reg: 06-11-19
06-17-19 12:01 PM - Post#2768693    

My coolant temp reading has not been functioning. I tested the gauge by taking off the wire from the sending unit & it was full C when ignition was on and not touching anything and full H when I grounded it so I believe that tells me the gauge is ok.
The motor is a 235 from a Chevy 58-62 car, so I replaced the sending unit with a ACDelco G1852 Professional Engine Coolant Temperature Sensor
Now the gauge reads C at start up, but as soon as things start to get warm it pegs to all the way to H.
The truck isn’t overheating and there is no progression of the needle – it just pegs.
Any ideas to help me diagnose the issue?


"16th Year" Gold Supporting Member
Posts: 1470
Loc: Chandler(it's a dry heat)...
Reg: 04-26-04
06-18-19 09:56 AM - Post#2768751    
    In response to Tim-3200

I'm guessing that is the wrong type of temp sensor. The way to check is to disconnect the guage and use an ohmmeter on the sensor from cold to hot. If warm goes to near zero ohms thats the problem.

'56 3100 Short Stepside Someday
2001 Chevy Suburban 2500
2009 Saturn Vue w/20's

Member: Desert Classic Chevy's Inc.
Monty's 56 Truck
Avatar is my Truck

Posts: 3

Reg: 06-11-19
06-18-19 12:44 PM - Post#2768759    
    In response to monty56

Thanks Monty, I'll follow that line

"9th Year" Silver Supporting Member
Posts: 1654
Age: 72
Loc: Las Vegas, NV
Reg: 10-26-04
06-18-19 09:14 PM - Post#2768790    
    In response to Tim-3200

That sounds like a switch for a light instead of a gradual resistance needed for a gauge.
This link confirms it. rature...
This should be the correct one ...


57 210 4dr. Wagon(bought '82)
-350/700r4 Mild Custom
29 Ford Sedan(bought '75)
-4.3L/TH350(in progress)

Edited by WagonMan on 06-18-19 09:23 PM. Reason for edit: Added links

Posts: 3

Reg: 06-11-19
07-03-19 09:48 AM - Post#2769821    
    In response to WagonMan

Thank you for the link to this part!

Valued Contributor
Posts: 3875

Loc: Eagan MN
Reg: 06-02-03
07-09-19 06:37 PM - Post#2770333    
    In response to WagonMan

Generally speaking the temp sensor for a gauge will have 1 terminal and sensors for idiot lights will have 2, one wire to the "cold" lamp and the other for the "hot" lamp.

For a gauge you need a 1 wire sender calibrated to work with that gauge. So if you have a newer engine, you still will want to use the sender from the original engine to match the original gauge.

Proud owner of My Blue 62 Impala SS


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