Hey y’all, my 1999 3.0l v6 flex engine is not getting up to operating temperature. It gets up above the C on the gauge and will drop when I come to a stop. I just replaced the thermostat and did a full coolant flush to see if that would solve the issue and it didn’t. There is also no heat coming into the cabin. The radiator fan kicks on as soon as the engine comes on. Not sure what’s causing this. Gonna back flush the heater core this weekend to see if that helps. Any troubleshooting help is very much appreciated!

 

Just picked one up today and having the same issue radiator welds were blown so had to patch it up and wondering if theirs an imbalance of pressure in the system but not sure why even after replacing thermostat why it would still happen I may be able to flush my heater today depending on work one of us will figure it out lol

 

Hopefully one of us will figure it out haha. I’m headed back home after spending time with family and I’m ready to be back to figure out what’s going on. I’ll keep you updated.

 

Fo

​​So reading some of the older posts both these engines run pretty cool and their are a lot of issues with thermostats now either not being accurate or staying open all the time. This guy went and bought some fancy stuff and actually measured the temperature in multiple points on the block and radiator and the 2.3 s actually just run that cold and should sit their based on the manuals recommended running temps again this is primarily to the 2.3 Lima engine like I have but some have mentioned it about your 3.0 as well but heater seems to be the old general fix these trucks seriously last forever

 

Cooling fan can matter but not that much

Rangers use 190-195degF thermostats

Simple test for thermostat
Cold engine
Start engine and open the hood
Feel upper radiator hose and both Heater hoses at the firewall, all stone cold

Let engine idle for 3 or 4 min, then feel the hoses again
Heater hoses should be warming up
Upper rad hose should still be stone cold, if its getting warm then thermostat is not working, new or not

The radiator on any vehicle is to get rid of EXTRA HEAT, in winter months it may not even be used
Its external to engine's cooling system
Water pump circulates coolant thru the engine and heater hoses
IF..........coolant gets to 190degF at the thermostat it will open a bit and allow some of the coolant to flow to upper radiator hose which pushes out cooler coolant thru the lower radiator hose and into the water pump
But this is only IF coolant in the engine gets to 190degF, which is just below 1/2 on Ford Temp gauges

Thermostat are SUPPOSE to fail open, this prevents overheating in the engine, so if upper rad hose heats up the same as heater hose then thermostat is bad


Fan clutch can cause engine to run cooler but 4cyl engines usually not V6's
Open hood on engine that has not been running for at least 5 hours, overnight is best
Try to spin fan, should be hard to spin, cold locked
Start cold engine, you should HEAR fan pulling in air but that sound goes away after a few seconds
Shut off engine
Try to spin the fan
If it spins easily is unlocked which is good
If its hard to spin then its locked, replace fan clutch

If fan was easy to spin when cold locked then replace fan clutch as well, that can cause overheating in summer months