Temp gauge and sensor and thermostat
August 29th, 2017, 10:43 AM
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Temp gauge and sensor and thermostat
2000 K2500, 5.7l, basic worktruck package... about 135K miles.
My truck has appeared to be running cool for some time, so I replaced the thermostat. The old one was indeed stuck open just a bit, but after replacement with a 195 degree thermostat, the gauge did go up but only to about 165 or so. Before replacement of the thermostat, it was reading around 110-ish. I tried another new thermostat, same thing - stable at about 165. I tested the gauge arm movement by connecting the connector pin to ground and starting the truck - the gauge pinned all the way high, so seems to work. I just bought a bluetooth OBD2 unit, and the temperature there looks good - warms to 195 and then regulates.
The question: should i still replace the sensor at the engine block? Would that be likely to fix the problem, or is the gauge itself bad? Does the OBD2 unit 'look' at the same sensor as the gauge? As long as the computer is reading an accurate and on-target temperature, should I just not worry about it? I'd like to be sure that that I'm not giving the computer bad info and therefore running a rich because it thinks it's cool. My truck is on the lower end of what I'd expect for gas mileage, but not horribly off - I average around 12-12.5mpg, but know that others with this rig get closer to 14-15mpg. Would love to get there if I can.
Many thanks for any thoughts - your help is much appreciated.
My truck has appeared to be running cool for some time, so I replaced the thermostat. The old one was indeed stuck open just a bit, but after replacement with a 195 degree thermostat, the gauge did go up but only to about 165 or so. Before replacement of the thermostat, it was reading around 110-ish. I tried another new thermostat, same thing - stable at about 165. I tested the gauge arm movement by connecting the connector pin to ground and starting the truck - the gauge pinned all the way high, so seems to work. I just bought a bluetooth OBD2 unit, and the temperature there looks good - warms to 195 and then regulates.
The question: should i still replace the sensor at the engine block? Would that be likely to fix the problem, or is the gauge itself bad? Does the OBD2 unit 'look' at the same sensor as the gauge? As long as the computer is reading an accurate and on-target temperature, should I just not worry about it? I'd like to be sure that that I'm not giving the computer bad info and therefore running a rich because it thinks it's cool. My truck is on the lower end of what I'd expect for gas mileage, but not horribly off - I average around 12-12.5mpg, but know that others with this rig get closer to 14-15mpg. Would love to get there if I can.
Many thanks for any thoughts - your help is much appreciated.
Last edited by MissionValley; August 30th, 2017 at 9:44 AM.
September 20th, 2017, 12:28 PM
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If you want to know what your actual temp is, use an infrared thermometer to check the temp at the thermostat housing. If it is close to what your scanner says, it is likely the gauge is off. If you are aware the gauge is inaccurate, you can replace it or you can try to determine how far off it is and if the error is consistent across it's entire range and then just figure out were too hot would be.