ECT sensor, can it be tested?

[57chevyragtop]

(engine coolant temp) Just curious if there is a test that will tell if an old sensor is good. I know you can test a thermostat in hot water. but wouldn't you have to test the resistance or voltage across the contacts on the ECT as water temp in pan rises?

[Tech II]

Yes, the temp of the water should match the variable resistance of the contacts......perhaps someone can post the values for you.....

[777stickman]

Here's some temp vs resistance values for a '98 5.0/5.7. All temps are in Fahrenheit.

50=5670 ohms
104=1459
194=241

[j cAT]

Originally Posted by 57chevyragtop

(engine coolant temp) Just curious if there is a test that will tell if an old sensor is good. I know you can test a thermostat in hot water. but wouldn't you have to test the resistance or voltage across the contacts on the ECT as water temp in pan rises?

to test the ECT you would need to use temps at least to 0 deg f to 212deg f.

the cost of these are not much. testing at 32 deg f and boiling should indicate if you have a problem.

[j cAT]

Originally Posted by 57chevyragtop

(engine coolant temp) Just curious if there is a test that will tell if an old sensor is good. I know you can test a thermostat in hot water. but wouldn't you have to test the resistance or voltage across the contacts on the ECT as water temp in pan rises?

http://www.napaechlin.com/GM-Coolant...s/Content.aspx

[57chevyragtop]

I want to thank all the respondents above for their replies. I just finished the testing of a new ECT sensor I just removed from my engine. Read correctly to 600ohms then started jumping to 1800 1900 back to 500 then 1600...well, all over the ohms field as the temp was rising above 196 deg (water temp). So as expected it was a bad new (but cheap) Brand->Standard T-series part, made in Mexico! I put in an old ECT sensor ( NAPA-Echlin) Made in the USA and everything is running fine now. I thought perhaps it was the connector or a short in the wiring that was causing the engine idle and gauge problems I was having. Having test driven the car 30 miles or so, all is back to normal. Your input did help me and I am sure I will need help again someday.

[j cAT]

Originally Posted by 57chevyragtop

I want to thank all the respondents above for their replies. I just finished the testing of a new ECT sensor I just removed from my engine. Read correctly to 600ohms then started jumping to 1800 1900 back to 500 then 1600...well, all over the ohms field as the temp was rising above 196 deg (water temp). So as expected it was a bad new (but cheap) Brand->Standard T-series part, made in Mexico! I put in an old ECT sensor ( NAPA-Echlin) Made in the USA and everything is running fine now. I thought perhaps it was the connector or a short in the wiring that was causing the engine idle and gauge problems I was having. Having test driven the car 30 miles or so, all is back to normal. Your input did help me and I am sure I will need help again someday.

good report on your findings. thats why I stated to test from 32-212 deg f. as these fail at any point in the operating range.