Cooling questions

[Johnnyboiranger22]

Hey Guys Im finally getting ready to put my 91 Ranger on the road but I want to make sure cooling system is a okay. My first question is what the average coolant temperature? 200? 190? The lower hose should always be cooler than upper hose right? Further more how to tell is fan clutch is operating correctly? The reason I ask is because engine bay is def hot but my gauge barely ever moves from the cold position and i swapped thermostat,water pump, ECT Coolant sensor and gauge temp sensor and still no change. Should i be worried at all? I bought a Infrared thermometer and will testing out temp of hoses

 

[bilbo]

Did you replace the thermostat housing by chance?

 

[RonD]

Upper engine at thermostat should be 185-195 after 8 minutes of driving, or 10min idling, if thermostat is 190-195, stock temp

Lower rad hose should be 20 deg cooler than upper hose, after warm up
Radiator is there to get rid of EXTRA HEAT, so in colder climates it may not even be used, thats the purpose of the thermostat, if coolant in upper engine reaches 190deg then it will open a bit and send EXTRA HEAT out to radiator, then close again until temp goes up above 190 again

Your coolant temp SENDER, for the gauge, is at the back of the engine so not true upper engine temp, not sure why Ford did that?
So on the 2.3l engines the gauge shows lower temp
You can move the sender to upper hose, heater hose, to make it more accurate , thats what Ford did in later years on this engine

Before starting cold engine, open hood and try to spin the fan, should be tight, not spin easily, locked
Start engine and let it run for 10-30 second, shut it off
Spin fan again, should be easier to spin, unlocked

If fan is still locked then replace fan clutch

 

[Johnnyboiranger22]

Thanks guys for reply! So I checked temp with laser gun (which might not be all accurate) but block read 150 degrees same for top. Rad hose was 140 degrees and bottom was about 15 degrees cooler. I can tell when thermostat opens as upper rad hose gets harder to squeeze

 

[RonD]

Rad hose upper or lower should have same pressure, or radiator is blocked

The Pressure comes from coolant warming up, all liquids expand when heated, so as an engine heats up the coolant, it expands in volume and creates internal pressure in the whole system, pressure travels thru lower rad hose to the radiator, so pressure in upper hose would come from that
Rad cap holds in the pressure until its just over 14psi then it opens a bit and lets some hot coolant flow out to overflow tank
After engine is off, and cools down rad cap SUCKS coolant from overflow tank back into radiator

Upper hose should not heat up after cold start, should be 8-10 minutes before thermostat opens to let warm coolant flow into upper hose
If upper hose is warming up with the engine then thermostat is leaking or partially open