Join Date: Sep 2003
Location: Northern VA, USA
With the thermostat stuck wide open, it will still reach 195 F but it will take much longer. One that is stuck closed will over heat in a very short period of time.
I stuck my coolant sensor (at the thermostat housing) in a pot of water and measured the resistance with increasing temp. Then I co-plotted my data with the factor service manual data, using MS Excel. They over-laided one another. So is good.
A smarter way to it would be to back-probe the coolant temperature sensor, once the thermostat has opened, and extrapolate the temp from the FSM valves. This is how I know that my thermostat is functioning properly and that my dash gage or the dash age gage sender is wrong.
94 Black Laredo 4-Liter with QuadraTrac (42RE trans & NP249 TC) 200,000 + miles purchased new
88 Cherokee 2-door with 5speed manual 139K miles(deceased) purchased new