I know these tend to run on the hot side, but at what temperature does it enter in to the realm of "too hot"? I have just replaced the thermostat (and gasket) with a brand new overpriced Motorcraft one. In the last couple of years I have replaced all hoses, the water pump and the degas bottle (it was leaking). The only thing left that has anything to do with the coolant is the radiator and the heater core.

I am running straight distilled water now and when I go out and drive it, the ECT gets up to about 240-250 but if I get on the throttle hard for a short spurt it will shoot up to 260+. I notice the temp gauge stays in the middle until about 255-260 and then it starts rising. When that happens I can just put it in neutral and coast and the ECT comes down to 235-245 fairly quickly. 262 is the most I have seen but I very quickly reacted and put it in neutral. All of this is on a 45-50 degree day with the heater running full blast. I assumed running the heater helps cool the water at least a little.

When I stop and get out, the big hose coming to the top of the radiator is fairly hot, the left side of the radiator is fairly hot too. But the bottom hose is not just cool but very cold.

I have poured a fair amount of distilled water in the top side of the radiator with the lower hose off and it runs out fairly quickly so I assume the radiator isn't clogged up. When the thermostat was off I could turn the pulley and the water pump impeller would turn. While I have heard of people having rangers that run at 260, I know that I have never seen my temp gauge start to go up above the mid way mark like it is now. I also have one of those engine block testers. I put the fluid in and put it on the degas bottle and the fluid remains blue so there are no exhaust gases in the coolant so the headgasket should be ok.

I have wondered if the electric fan is coming on when it should, but I really can't tell if it is working because I can't get a good look at it when the engine is running.

Does anyone have any ideas what could be going on? I am going to power up the fan with the motor off to see if it is working. Other than that I have nothing.

 

2.3l Duratec engines have CHT(cylinder head temp) sensor and some also had ECT(engine cooling temp) sensor, but not all, V6 engines all had ECT and no CHT
Whats the CHT showing at these times?

If you are using a scanner to read temps then it may says "ECT" but is really getting CHT temp, so make sure

These engines don't run hot, normal operating temp for coolant is 190degF to 220degF, shouldn't go much higher than that even pulling a load uphill, at 230degF I would suspect a problem with circulation.

CHT sensor would definitely show the numbers you have posted, it reads temp of metal in the head, not coolant

Upper hose should not be touchable at 250degF, let alone 260degF
260degf is the start of OVERHEATING Range.

Distilled water boils at 212degF, if you add 14psi pressure(rad cap rating) you get 30 more degrees until water boils, so distilled water would boil at about 242degF, and that would BLOW OFF hoses if that happened, pressure would just to 60psi instantly.

50/50 coolant boils at 270degF with 14psi rad cap

So not sure your temps are correct, ECT sensor, if present also runs temp gauge, so temp gauge and computer data for ECT will be the same, it isn't a "comparison"
With only CHT sensor then computer runs dash temp gauge
Ford temp gauge should run just below or at 1/2 way when engine is at correct operating temp

Thermostat is on the lower Rad hose as you know from changing it.

Coolant flows out the upper hose in to the rad then should be cooled 15deg without fan on, and 20-25deg with fan on.
Then flows out of rad into lower hose and into the engine.

Radiator is only used for EXTRA heat, on cold days it may never be used or used very little, especially with heater on high.


From your description there is no flow thru the radiator, which might be normal with 45deg outside temps.
But could be because thermostat is not open all the way or radiator is clogged.
Could even be low water pump flow because of bad impeller.

Drain out the radiator.
Remove upper and lower hose
Put garden hose in upper hose opening and turn on the water
Make sure water is coming out the lower hose opening as fast as it is going in the upper hose opening.

2003 2.3l could have either an electric thermostat or non-electric, electric thermostat was 208degF, non-electric was 180degF
Electric is heated so it opens 208degF, which is actually when upper engine temp should be about 200degF.
180degF opens at 180degF and upper engine would also be at about 200degF
So they are basically the same which was why the electric one was dropped in 2003.



Fan will run mostly at idle and driving under 30MPH because when driving air flow thru rad is doing the cooling and fan isn't needed, especially when outside temp is under 60degF
Fan is controlled by the computer, based on CHT sensor, but if you have AC turn it on, that will some times activate a radiator cooling fan

I would double check you numbers first.

 

Thanks for the information!

I checked the relay for the electric fan and it works as it should. I also powered the fan and it works. So if the PCM is energizing the relay then the fan will work. But I wouldn't think the fan is of much use at highway speeds which is when I am getting the hot temperatures.

I am fairly certain mine has the ECT and the CHT. But the ECT is on the back against the firewall and is very difficult to get a look at so I am not 100% sure. But you are right that my scanner might be reporting CHT as ECT. I haven't looked at CHT as I haven't even found it on the scanner software.

I thought the same thing that the upper hose would be too hot to touch if it was really getting that hot. But by the time I have stopped and touched the hoses the ECT is reporting 220 or so. But still the upper hose is hot but not THAT hot. I can put my hand on it fairly easily. The ford factory manual implies that if the heater core hoses and the upper radiator hoses are hot then the thermostat is opening. The only thing that concerns me is how cold the lower radiator hose is. I haven't sprayed a garden hose in it, but I did turn up a gallon jug of distilled water and poured it in the top hose and it was coming out the bottom about as quickly as it was going in. But it does concern me that the bottom hose is pretty much cold. I thought (and you confirmed) that it would only cool it 20 degrees are so, but with the top hose hot (but not too hot to touch) the bottom hose actually felt cold, not even slightly warm.

But I think you are probably right and my scanner is reading the CHT. The only thing that concerns me is that I have never seen the gauge move above half but when the scanner number (whatever it was reading) hit about 255 the gauge started to move beyond half way by a bit. So that just makes me think the car thought it was getting hot whether the CHT was controlling the gauge or the computer was. Is it possible I have some air pocket in the engine? A couple of years ago when I drained the coolant to replace the degas bottle I followed the Ford manual procedure for filling and bleeding. I ran the engine at 2500 RPMs for 8 minutes (thermostat should be open), then hold that for 3 minutes more, then increase to 4,000 for 5 seconds, then back to 2500 for 3 more minutes. But this time I just took it for a drive. I assume their procedure is just a way to get the water to circulate without driving it and is actually nothing magical about that exact procedure.

My thermostat is definitely the electric one, and I replaced it with another electric one. I was going to use a non-electric and just plug the old one in to the connector so the PCM would be happy. But I decided to just put the electric one in.

Also, my degas bottle cap is a 16psi cap. So that might push the boiling point of water up closer to 250, but still, if it was hitting 260 then the water would have been boiling.

 

Dash Temp gauge would be correct, just above 1/2 would be correct if sustaining a load on the engine, i.e. going up a longer hill or accelerating for extended period, a minute or two

During normal cruising then just below or at 1/2 way would be correct for dash temp gauge

CHT should show outside temp before cold start, i.e. 45degF outside temp
After starting it should climb to 180degF in 2 or 3 minutes, coolant takes longer(ECT)
It should top out at about 215-220degF in 5 to 8 minutes, when thermostat opens.

When accelerating or otherwise loading the engine the CHT will be quick to react, climbing up much faster than a coolant temp gauge because it is in direct contact with cylinder head metal.
Coolant temp is an average of overall engine temp so there is a delay as coolant circulates thru the now heating up head and passes by an ECT sensor

 

I started digging deeper in my OBD-2 software and found the CHT.

The basic readings included ECT (or it is called that) and that was what was reading really high. When I went in to the enhanced/expanded data set I scrolled through and found CHT and ECT. I observed them while the car was heating up and noticed they all were within 1 or 2 degrees F until the temps got above 210. Then the CHT kept rising and the ECT was lower. It is much cooler today (45 degrees) and the ECT in the expanded data set seemed to run about 220 and under heavy load gets up to about 228. The CHT reading goes up to about 250 at times. But in general there is about 15-20 degrees between CHT and ECT.

The odd thing is that the basic "ECT" reading seems to follow the CHT reading as you suggested it might. They are always within about 1 degree of each other (I would expect them to be the same since it is obviously reading the same sensor). But the ECT reading from the expanded data set is more in line with what I would expect the coolant temperature to be. So it looks like you solved my problem.

I used a small inspection camera and I definitely do have a coolant temp sensor/sender on the back of the engine where the metal coolant pipe is coming around above the exhaust manifold and toward the degas bottle and radiator. Just to make 100% sure I check that pipe with an IR thermometer and see what it says. Also, after driving today I noticed the lower hose was above ambient temperature. It wasn't hot but it definitely wasn't cold. Thanks for your help!

 

Good work answering your question.

And just as a "heads up"

Your 2.3l Duratec engine was designed for transverse mounting, Front wheel drive cars.
That's why there is a coolant connection on the backside of the engine, it would be easy to get at if engine was mounted sideways, lol.

But it is hard to get at in a Ranger.
So if for any reason the transmission needs to be pulled out or back, you should ALWAYS replace this fitting and hose.

2.3l also use IMRC(intake manifold runner control) for extra power.
Quick explanation for this is:
An Intake runner is the tube to the intake valve on any engine, the length of this tube is designed/planned it is not just a random length that fits.
When engine is running an intake valve opens to pull in air/fuel mix then it closes, when it closes, air flows stops abruptly and a pressure wave travels back up the runner and hits the end of the runner and reflects back down the runner toward the intake valve.
If this reflected pressure wave gets back to the intake valve while it is open again then it acts like a mini-turbo charger, pushing in slightly more air/fuel mix, so engine gets more power.
With fixed length runners there is a specific RPM band where this extra power occurs.
IMRC changes the runner length based on RPM, so you get a wider RPM band with this extra power.

IMRC failure is common issue on the 2.3l Duratec, and usually it is just a cracked or broken vacuum hose to the IMRC servo that controls the IMRC rod movement
This servo and rod are also on the backside of the engine, but vacuum issue usually happens on drivers side of engine lower area where vacuum hoses come from

 

That is just the nature of the beast for these Ranger 2.3 Duratec engines. That lower radiator hose will be cold, to ambient temp, to maybe warm. It will never be hot'ish.