RedFox91

91 5.0 LX, car doesn't seem to warm up properly, even after 30 min of driving, the gauge is still pretty much pegged at the bottom. I have noticed that the radiator stays cool and the upper radiator hose is also cool to the touch. The recirc lines at the back of the engine that go to the throttle body are hot, and so are the heater in/out hoses. Not sure if its related, but the engine cooling fan runs constantly, its on whenever the car is running.

Car has new water pump and thermostat & housing, and both coolant sensors/sender are new. Any ideas as to why its not getting hot up front?

I'm trying to figure this out at home, so I haven't been able to pressure test it. Would trying a new radiator cap make a difference?

03gt04mach1

Is the thermostat installed backwards? Spring side should face engine block. The cap only helps to keep the coolant pressurized, and prevent coolant release, sealing the system.

Tony71502

Thermostat has my vote. Bad/installed wrong. If the spring isn't in coolant it will never get hot enough to open up if it is in air.

drhoward

Thermostat, it will never warm up properly if its stuck

RedFox91

The new thermostat was installed correctly. Must be bad out of the box? I'll have to pick up another one, what temp should I get?

im_stuck_in_iraq

depends on your mods, from what I understand. I went with 185 from 195 (stock) i think lol if 190 stock then i went with 180 *bad memory* *stupid ptsd*

9550

i think if you drop the t-stat in some boiling water you can check if its working. should open when it hits the boiling water or something.
somebody here smarter than i can give you more details