5.7L water temperature

[Phlorida]

My temperature gauge recently quit working. I went to my local parts store and bought a replacement temperature sensor which resolved the issue except that I am suspicious of the temperature reading. Prior to the issue with it, the gauge always read slightly under 170 degrees. Now the gauge reads slightly below 150 degrees which leads me to think that I was sold the wrong sensor. I believe that a running temperature for this engine (5.7L) is around 170. Any thoughts?

 

[mwph]

Generally speaking, the running temperature is determined by the thermostat you have installed. If your gauge quit registering and the only thing you did was replace the sensor, then I too would be suspect.

Does the gauge seem to be acting normaly? What I mean is does it "ramp up" gradually reaching 150? Do you feel confident with the sensor install? Just thinking aloud.

 

[Phlorida]

The gauge suddenly pegged and stayed there under any condition. When I removed the connection from the sensor the gauge went back to zero so the bad sensor was fairly easy to diagnose. With the new sensor the gauge acts normally and does a gradual rise to 150 degrees. It sounds like you are agreeing with me that 150 degrees is not a normal reading for my engine.

 

[Pack66Dad]

Mine both read about 150 degrees, I have new gauges, sensors and thermostats. My mechanic double checked everything and made sure the thermostats were per mercruiser specs for my engines. He was suspicious about the temperature readings too and checked them with a laser thermometer. He told me it was within a couple of degrees so he was satisfied the gauges are correct.

 

[CliffA]

My temperature gauge recently quit working. I went to my local parts store and bought a replacement temperature sensor which resolved the issue except that I am suspicious of the temperature reading. Prior to the issue with it, the gauge always read slightly under 170 degrees. Now the gauge reads slightly below 150 degrees which leads me to think that I was sold the wrong sensor. I believe that a running temperature for this engine (5.7L) is around 170. Any thoughts?

you likely have a 143* thermostat in your engine so it is possible that your normal operating temp is around 150*.....i replaced my thermostat last year with a 143* and my normal operating temp is around 160 - 165*.....the temp rating of a thermostat is when it 'starts' to open....for the thermostat to be fully open the temp of the circulating cooling water will need to be somewhat higher.....i suppose that different brands of thermostats open at different rates....the thermostat you have may start to open at 143* and be fully open at 150*...the thermostat i have may start to open at 143* and be fully open at 165*.....

cliff

 

[njmello]

A 143 degree t-stat is normal for saltwater use. Guages and senders are only 'reasonably' accurate. A lazer temp gun will give you a more precise reading to compare to the gauge.

 

[cain]

I don't have a 350 but a 4.3. My temp gauge always reads between 143-146.

 

[jag3man]

I'll chime in... The laser temp gauge is cheap and nice to have for lots of jobs but it works great on reading the temperature of your thermostat. As mentioned before the raw water cooled engine carries a 140 for the express purpose of preventing the salt to crystalize within engines water jackets and dramatically reducing engine life. This is somewhat at the expense of optimum engine performance as the engines enjoy being warmer than 140-150. Buy yourself a new toy from Lowes or Homedepot or harbor freight. You'll sleep better. If you do get wildly divergent numbers it is possible that the sensor you have is NOT compatable with the gauge you have installed. They are NOT universal as the circuitry is based on resistance of the sensor with regard to the meter movement.