Defective coolant temp sensor

csdaddy · January 29, 2007

I recently installed a set of Gibson headers to my 2000 K3500 7.4 Liter. The coolant temp sensor was damaged then replaced. Now the temp gauge reads at the mark between 100-210. Assuming this is around 155, the truck

has never ran this cool. Always 180-185. There is a hypertech 180 thermostat installed. Should the temp sensor

be the first place to start to diagnose this?

Haulin' 8.1 · January 30, 2007

First thing to check would be that the ground straps all got put back and are tight and clean. A poorly grounded engine is a likely cause of this problem.

The only way that engine will run that cold is if the thermostat is stuck open. Start the engine and see if the upper raditor hose starts heating up right away. It should remain cool until the thermostat opens for the first time.

If it's neither make sure you got the right sensor, likely you did. There's always the gauge or instrument cluster that could be defective. But seeing as it occured during the header job I'd start under there.

Vernon

90GMCZ71 · January 30, 2007

What brand of temp sensor was used? I find it best to use AC Delco sensors.

//90GMCZ71

redvett · January 30, 2007

I would start by scanning the coolant temp on a scanner and find out what the PCM is reading and go frm there the guage is just an indicator and could be wrong. The scan tool will do a digital readout.