2.3L Duratec - Overheating Issue

[Scannell]

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.

 

[franklin2]

How do you know it's overheating? I am hoping to hear it's spewing coolant, it's pinging, oil leaks on the engine are smoking, etc. I hope you are not going just by the factory gauge and what it's telling you.

 

[Scannell]

In addition to the gauge on the dash, I am also running Forscan and getting the readings from the cylinder head temperature sensor and the coolant temperature sensor at the back of the head, while double checking that with a temp scanner on various parts of the cooling system.

 

[franklin2]

In addition to the gauge on the dash, I am also running Forscan and getting the readings from the cylinder head temperature sensor and the coolant temperature sensor at the back of the head, while double checking that with a temp scanner on various parts of the cooling system.

What readings are you getting?

 

[dvdswan]

Welcome to the site.

Its obviously having a flow problem at highway speeds. You could have several rows clogged in the radiator and still have good flow. Are you sure when you did your head work that no gasket pieces fell into the block reducing flow?

Does the temp go down if you turn on the heater?

 

[Dirtman]

Duratecs run hotter than normal by design but should still stay steady once warmed up whether idling or at highway speeds.

Is the electrical fan functioning? Should come on with AC or if the vehicle begins to overheat regardless of whether AC is on. When the vehicle is overheating is the upper and lower radiator hose at the same temperature? Have you checked all other parameters? When you had the head off did you get the timing back on perfect and replace the diamond washers to ensure no slip in timing? Are the fuel trims reading good and not showing an over lean issue? Is ignition timing advancing properly to indicate no issues with pinging? (knock sensor would pull the timing way down).