Walter Buller
Member
Next question: Today I installed a new 180 degree thermostat in my "94 Chevy dually with the 5.9L 12v Cummins motor because the new Bosch temperature gauge that I installed yesterday reached the 250 degree mark a few miles from home and even went beyond that to an estimated 275 degrees. But oil pressure was still good and the radiator was not blowing out coolant, nor did the motor have that "hot" smell. When I got back to my shop I used 2 of my wife's thermometers to check actual engine temperature. One is a stainless, sharp pointed meat temp. tester. The other is a glass candy thermometer. It is about a half inch wide and tapers down at the bottom to the bulb that contains the mercury. On the casting that holds the thermostat is a hole about 3/8ths of an inch wide by about an inch or so deep. It is only about an inch away from the take-off point where the line to the temperature gauge is connected to the head just behind the thermostat. I filled this hole with water while the engine was running, with the Bosch gauge showing 240 degrees. After waiting a minute for the water in that hole to reach the same temperature as the motor, I put the meat thermometer into the water. It read 165 degrees. Then I immersed the bulb at the bottom of the candy thermometer in the water in that hole and it read a steady 180 degrees, which it should inasmuch as the new thermostat opens at 180 degrees. So, would any of you care to comment on whether my method proved that the Bosch gauge is reading about 60 degrees to high? Thanks in advance.