[lemontcars]

I bought a repo. temp gauge but it will not give me the proper engine temp. the fuel gauge works fine the repo gauges do not have the resitors on the back they are connected internally the gauge shows 100 ohmes the sender at 210 degrees is 100 ohmes you would think it should be correct a mechanical gauge is about 20 degrees less? any suggestions? Marty

 

[68Phoenix]

I can't stand these differences. I changed the location of my mechanical water temp sensor (moved it to the manifold from the heads) and the temperature readings dropped from 190 to 160. You'd think most gauges would have a calibration screw or something....

 

[Birddog1970]

I have the same issue with my repro gauge on my 70 SS. The mechanical gauge ran right at 190 but the dash gauge runs at 220. My sending unit is on the head. Haven't tried to trouble shoot yet, I'll let you know if I come up with something

 

[lemontcars]

Birddog1970, it is the most difficult to figure out I have tried everything I can think of if you figure it out I sure would like to here from you thanks, Marty

 

[Steve S]

Did the repro gauge include the sensor? I think the sensor for the repro is different than stock. I bought the complete repro set for a customer and the instructions said to use the resistor from the back of the old large fuel gauge and put it on the temp gauge.

 

[lemontcars]

Steve, first the repo gauges did not come with any instructions,or sending unit, I never had a large fuel gauge, because I have a clock, my car came with gauges the temp gauge did not work right was always higher the the actual engine temp. I verifed the engine temp with a mechanical gauge which showed when the 180 thermostat opened etc. ran about 190 when it was all warmmed up so I thought I just get the repo gauge and quit playing around well that showed it running too hot again,I changed the sending unit now it was running too cool still not right, I bought a "corrected" GM sending unit guaranteed to be acurate runs too hot no matter what I have done it does not show the correct engine temp. really frurustrating, Marty

 

[71ChevelleConvert]

I had the same problem. If you have you old gauges there are 2 resistors on on that set-up.One on the fuel (orange)and one on the temp(blue)the newer gauge uses the orange one connected up and down on the 4 post. If you still reading low and I hope you are at this point just run a seperate ground from gauge assy (both fuel/temp) and to the firewall. That should fix ya up.I installed a painless harness and a newer set-up and even the people who sold it to me on EBay didnt know how to fix the problem.

 

[lemontcars]

71 ChevelleConvert, the repo gauges do not require the little resistor on the back, that was the first problem the repo gauge has the resistance built in you can measure the ohms it should read about 100 ohms if you add the external resistor on the back you increase the resistance and the gauge will read colder than it really is and with out it, it will read hotter than it is? it has been driving me crazy thanks, Marty