I have a 2001 with the 2.3L Duratec that is overheating and I am stumped at finding the cause. It mostly overheats when running highway speeds but if I run it around town long enough the temperature will start to climb.



I have no coolant leaks and there is no coolant in the oil. When I pressure tested the system and it tests perfectly. The radiator has been flushed out with a hose and seems to have good flow. The front of the radiator was also cleaned of any blockage. I took apart the water pump and everything looks and works as it should. The fan clutch will turn easily by hand but has enough resistance to not spin. I replaced the thermostat with a mechanical Motorcraft version for a 2005 ranger and that little effect other than taking a little longer to overheat. The system has been bled per the workshop manual instructions twice. I am stumped, is there something that I am missing?



Background:

This started when I had a crack in my degas bottle that was leaking when pressurized. I replaced it with an aftermarket one and couldn’t get it to seal properly so broke down and purchased a Ford replacement part. A couple months ago I also had the cylinder head off to repair a valve that wouldn’t seal properly and replaced both of the cooling system gaskets and the hose while I had it off. I did not notice any heating issues at that time.

 

Sounds like that's your problem,
Completely cold, like first thing in the morning, it should be very difficult to turn by hand.

After 3 to 5 minutes or so of running, should be fairly easy to turn by hand.

Once engine is up to operating temperature, it should be very difficult to turn by hand.

 

Overheating at highway speed points toward a CoolantFlow problem, not a Fan\AirFlow problem.
Even though you've hose it, plugged radiator is suspect, especially if its the 2001 factory original.
I'd change both radiator & pump if they're both original.
Consider replacing the old 1or2RowPlasticTankedRadiator with a new 3or4RowAllAluminumRadiator.

 

Well I checked my fan when I got home from work and even when the vehicle reached operating temperature the clutch resistance never changed. I have ordered a replacement and will check and see if that helps the situation. I do not know if the radiator is the original but I did replace the pump a couple of years ago.

 

Seems to me that if your running down the highway, a pretty good amount of air is gonna blow through the radiator regardless if the fan spins freely or not. I think Dillard may be on to something about coolant flow itself. If your intent on replacing the fan clutch, i would take the extra step and pull the radiator out at the very least and flush it with a hose at full blast and see what comes out. If its clean as a whistle and flows good out the other end, than your good. If not. either keep flushing like there is no tomorrow or replace. Verify that the thermostat is installed correctly also.

 

Dillard, you had suggested an all aluminum radiator with more rows. I couldn't find any for sale for the duratec, do you know where I could find one?

 

Yea be careful as the 3.0 and 4.0 V6 radiators are different from the 4 bangers. The ports are on opposite side. Sure is plently of 3 rows for the V6s.

Did find a single row all aluminum one for the 2.3: https://www.ebay.com/itm/29429135287...cAAOSwb4VbxPMb

Not sure the stock 4 banger is gonna warrant a 3 or 4 row radiator in the first place.

 

Take careful measurements of your exising radiator, noting the
~ inlet & outlet sizes & locations,
~ mounting bolt locations,
~ top & bottom channel depths,
~ core width & heighth.
If you've currently got a closed system with a degas bottle+cap without a radiator cap,
an all aluminum radiator of the same dimensions with a cap\neck can be used with a simple nonpressure rated cap;
radiator suppliers often ship these with the new radiator.
I suspect you can use same 2\3\4row radiators listed for the 2001 Ranger\MazdaB with the 3.0\4.0L V6.
Again take your careful measurements & compare to whats listed on Amazon\Ebay\RockAuto.

 

One other thing to look at is the sending unit. Maybe you are not overheating at all but the gauge makes it look like you are! When it over heats do you hear it boiling?

 

I replaced the fan clutch and that helped but only slightly. I am going to flush out the radiator again before considering replacement. Both the cylinder head temperature sensor and the coolant temperature sensor are showing comparative data, however, from what I've read it isn't too uncommon for both to go bad. The cylinder head temperature sensor was replaced last year when I was doing some other work and broke the plastic part of it but the coolant temperature sensor hasn't been replaced as far as I know. I will look and see if the workshop manual has a test for testing the coolant sensor.

 

As an experiment I'd try and run it w/o a thermostat and see if that's the culprit. Easy to do. My truck didn't have one when I bought it. They just had the hollowed out frame the the thermostat in there for the gasket seal. That's why my truck never heated up to operating temp. I'd be in south Florida traffic with AC on max and truck would never reach normal operating temp. My first instinct is it's your thermostat. Even though you replaced it. You could remove it and test it in boiling water. Or you could take it out and put rubber seal in there and bolt it back on and test drive. It should be a very dramatic difference. Engine will read cold no matter how you drive it. Probably bad for fuel economy if it never warms up. But then you'll know.

 

Using a garden hose to determine if the rad has good flow isn't very effective.
You can have it all blocked up with 10 vanes free and the water from the hose will flow freely through the unblocked passages.

Drive it until it starts to over heat, shut the engine off and feel with the palm of your hand on the rad surface, a healthy rad should be hot all over, any cold spots indicate blockages or places that are not the same temperature as the rest indicates only partial flow.

Check any new thermostats on the stove _ start with a pot of cold water and bring the heat up, it should be fully open before the water comes to a full boil.

 

Your right, its not going to be effective in most cases. I was lucky with mine as i pulled mine out, flushed from output end and started seeing so many rust particles come out other end until i had none left. I was also shaking the radiator with water in it and moving it all different directions. I did see much better flow after all this. Is it 100% effective? No, but it was much improved and saved me some cash.

 

Well I ended up biting the bullet and replacing the radiator. (Had to go with a stock plastic/aluminum one instead of an all aluminum one because they are just a little too big and don’t have the hooks for attaching the auxiliary cooling fan). It now runs with no issues. Thank you everyone for your advise!

 

What brand of radiator did you with, Spectra radiators were available at the time when I replaced mine, and they're made in Canada, or at least assemble here _ it's been in there for quite some time and no problems ?