stahlex Posted May 1, 2012 Share Posted May 1, 2012 I run truck and I can't get the gauge to read up to temp. It reads 10-15 degrees low. I shot the motor with my heat gun and it reads 187 degrees at water manifold at idle, but gauge reads low. Does this sound like temp sending unit, or the gauge, or something else entirely? Thanks. Quote Link to comment Share on other sites More sharing options...
stahlex Posted May 1, 2012 Author Share Posted May 1, 2012 Now I read the temperature at the thermostat housing and it is 187 degrees but at the back end of the water manifold, where the sending unit comes out of, it is about 175 - 177 degrees. The bottom coolant return pipe reads about 69 degrees. I am wondering if possibly the thermostat may have a little gasket material in it as I had my local Mack dealer last fall put new head gaskets on the truck and it has been sitting all winter. What do you think? Quote Link to comment Share on other sites More sharing options...
macattack Posted May 2, 2012 Share Posted May 2, 2012 to test gauge. remove wire from sending unit and ground it out. if gauge is good the needle will move over to max. if it does not go to max gauge is faulty.also what temp is your thermostat? should be around 180 or 190. Quote Link to comment Share on other sites More sharing options...
stahlex Posted May 2, 2012 Author Share Posted May 2, 2012 Yes, I have a 180 degree thermostat. Quote Link to comment Share on other sites More sharing options...
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