Okay. I bought a sunpro water temp gauge cause the last owner cut the sending wire and i cant find it. I attached the new sending wire to the stock temp sensor cuz i couldnt find a sensor that fit. whenever the engine is warmed up, it says like 270F(around there, ill be sure tomarrow). But tonight it is 55F and the car has sat all day. I turn on the gauge with the car off and it says 125F so it is a 70 degree difference. this means that i think my car runs at like 200F. I read somewhere under 210F is alright. Do you guys think its safe to think that its alright.

 

it's a bit of a hassle, but if you put the sender in boiling water you could check the tempreature reading at much closer to operating tempreature.

{ 212° = boiling water @ sea level, decreases with altitude }

is there an adjusting screw on the guage ?

if not, you might get the guage closer to right by adding a resistor to the signal wire {50/50 chance that adding resistance will move the needle the right way }
{{ I have no faint idea WHAT resistance will work, you'd just need to try some different values and see what happens, it cannot hurt anything.}}


your turning the cold car on to check the cool temperature is OK for a rough check but I would be concerned about the different rate of change in the air temperature and the engine temperature, the engine will change temperature more slowly than the air will.

as in the air could drop 20° in two hours, while the engine only dropped 7° at the same time. = 13° difference. { numbers grabbed out of thin air for illustration }

not to mention residual heat if the car had been run that day.

 

I always assumed it was alright because it goes up to the temp and stays there it never fluctuates or acts like its overheating. the engine compartment doesnt feel hotter than usual or anything

 

it sounds like it IS most likely ok, it is that "most likely" and "assume" that bother me.

as it is, you are using the guage more like a idiot light, you will know there is a problem when the reading changes, I would rather have the guage as a reasonably calibrated thermometer.

but then, I am paranoid.

{ my use of "idiot light" was, of course NOT a sneaky way of getting the word idiot into the conversation }

 

the problem with sunpro, autogage, and other pep-boy/cheap auto parts brand is the thermocouple is not sealed like the autometer, S&W and the cheap summit brand gage. instead, it is wrapped with metal loom; therefore, it will pick up additional heat from the engine compartment. As I mentioned earlier, summit sells a cheapy gauge for about $25. Its marked summit racing but works as great as the autometer.

 

could it be that i used the stock sensor instead of the sunpro one?

 

sorry, I didnt realize that youre using an electrical gauge. my reply applies to mechanical gauges.

...the stock water temp gauge wire is YELLOW. not hard to locate in the wire loom.