Originally Posted by rodjr
new gauges and senders, everything works except temp. went through trobleshoot, gauge has 21 ohms across terms, test light flashes on purple wire and at sender, with wire connected to sender light flashes same or tiny bit dimmer. heating sender reduces ohms. also tried 2nd sender nothing works. how does temp gauge ground, does it have ground?
I just went thru the TEMP Problems also. My gauge would read but alway low and below the greeen line. External temp test with pyrometer showed my thermostate was opertating at the correct temp 190 or so.
Just so you and others know, Them temp sender in there was 68 ohms at boiling water temp, 212 F approx, and was not low enough. OPeratioal temp around the boiling point of water for the sender is 30-35 ohms or so. I purchased one from Napa and boil tested and was 220ohms at boiling. This budget sensor would also jump in resistance and did not seem to be a good sensor, I suggested Napa not put that one back in stock. Napa suggested premium Elkin at nearly double the price close to $12 dollars but did measure the 30 ohms at boiling water temp. PUt in and now midscale at opertional temp. PERFECT!
Once you find a temp sensor that measures the correct resistance in boiling water, I would also measure resistance from the block to the output of this temp sender, thermister, to verify you have proper gound to block. Do the installed test at operational temp and should be about 30-35 ohms. Teflon tape or thead sealant can interfere with the ground of sensor to the block. I used a thread sealant but skiped the first 3-4 threads so I would still get good ground. I was also suprised by a squirt of water like a hose when I removed the sensor and engine was cold over night.
I do not recommend using the heat gun to test the sensor's output of ohms as posted above, you may over heat and the temp range the sensor. Heat guns can easyly approach 1000 F degrees. A guess on my part but a good one. Boiling water is a much better test and can be done prior to install.
Please let us know if that helped you out.