Low coolant temperature (F150, idle, fuel, MPG)

[HappyRider]

My Ford 4.0 liter V6 coolant temperature gauge sits well below the half way mark. I do have plenty of heat but I wonder if this is something to be "fixed".

[LIFL]

Wow, you have been having a lot of problems with that thing.

[Hemlock140]

If your thermostat is stuck open, it's not going to cause any harm if you still get enough heat, but it's an easy test and easy, cheap fix. You may find in the winter when it's below freezing outside that you do need more heat.

[Electrician4you]

My f250 temp guage sits below the 1/2 way mark. Pretty much every ford I ever drove or been a passenger in the temp guage reads around that. If you have heat and the temp guage ISNT climbing there is nothing to fix

A stuck open thermostat is bad. Granted a stuck closed one is worse but a open thermostat never allows the coolant to cool down by holding it in the radiator so eventually gradually can run higher temps

[SD4020]

No, there is nothing wrong with the temperature. It is normal for Fords to indicate cool.

[ukrkoz]

Coolant is not cooled down by being held in radiator. It is cooled down by heat exchange with either oncoming air flow, or one, caused by fan.
T-stat is there to simply deter coolant free flow through the system, to bring it to a particular temperature, usually - between 160 and 190 degrees. This is considered optimum operating temperature for a combustion engine.
NOTHING, besides cold feet, can be damaged by cooler coolant. As it physically can not stay cold in hot engine. What WILL suffer, is mpg, as ECM will keep believing that engine runs cold, and continue "warming it up". That normally comes at higher petrol consumption.
Also, as engine runs colder than meant to, carbon deposits will build up a bit faster.

The thermostat in most cars is about 2 inches (5 cm) in diameter. Its job is to block the flow of coolant to the radiator until the engine has warmed up. When the engine is cold, no coolant flows through the engine. Once the engine reaches its operating temperature (generally about 200 degrees F, 95 degrees C), the thermostat opens. By letting the engine warm up as quickly as possible, the thermostat reduces engine wear, deposits and emissions.

HowStuffWorks "How does the thermostat in a car's cooling system work?"

[BostonMike7]

Ford temp gauges are notoriously inaccurate.

I've used accurate Autometer temp gauges with the OEM factory temp gauge and found that the OEM gauge is pretty much an idiot light. Sure it may rise with temp initially but where it stopped was nowhere an accurate indicator of actual temp.

I've watched the aftermarket gauge swing 20-30 degrees while driving and the OEM gauge did not budge at all.

Replace the sender (if applicable) if need be, but if the coolant temp is at proper temp, i wouldn't stress out too much

[Nlambert]

It really depends on how cool it is showing. Our old Explorer would read just below the half way point (as does my 06 F150). If it's barely moving (as was the case with an old Dodge Ram I had once) then it sounds like the thermostat may be stuck open. While this isn't going to damage your engine, the ECM may try to increase fuel supply (you'll notice a higher idle all the time) to bring up the operating temps, which is going to consume more fuel.

When the t-stat in my Ram failed it read about 120 degrees all the time. I was getting about 8mpg as well. Once I fixed it the temp read 190 degrees and my mpg increased to about 11 mpg.

[HappyRider]

I have to see what happens when it gets real cold. Right now the heater works real well so may be it is normal.

[Miller88]

Ford's oil pressure and temperature gauges are fake.