Overheating

What engine 3.0L or 3.8L?

The ECT sensor is located on no. 13 see below

Be careful you choose the correct sensor: There are two water temp sensors in this same area. One is for the car computer to determine correct running parameters. The other one is exclusively for the dash temp gauge.

The one for the gauge should have only one wire attached to it (Red/White-stripe)
The other is for the car computer, has 2 wires (Light-Green/Red Stripe, and Grey/Red Stripe)

The sending unit with the two wires attached controls the fans, which ultimately cools the engine.

To gain access, you'll need to remove the intake snorkel & possibly the throttle body. If your fans are cycling on/off during extended idle, then the 2-wire sensor is doing its job and the 1-wire sensor is not sending the correct signal to the dash gauge. Replace the 1-wire sensor.

On the other hand, if your fans are not cycling and the coolant starts to bubble and/or steam is escaping from the pressure relief on the radiator cap, stop engine immediately, let it cool off for an hour or so. Replace 2-wire sensor.

Leaking cylinder head gasket. Common problem and common symptom. Your mechanic can do a chemical test at the radiator to verify that.

It's possible for fluids to mix but that is by far the least common symptom. There's oil draining back under no pressure, oil being pumped to the valve train under about 40 pounds of pressure, coolant under 15 pounds of pressure, and combustion gases under hundreds of pounds of pressure intermittently. Antifreeze becomes acidic due to the normal seepage of combustion gases into it. It has a number of additives including corrosion inhibitors that wear out in about two years. Because of that acid, and the high pressure in the cooling system, that is where most corrosion and leaks occur. It's not common for any oil passages to be involved with that leakage.

When there is a leak between the cooling and oiling systems, which fluid goes where depends on a number of things. Oil at 40 pounds of pressure might get pushed into the cooling system, but when the engine is stopped and still hot, the coolant will stay at 15 pounds for a minute or two, and that may not be long enough or high enough pressure to push coolant into the oil.

Check out some of our tips on this common issue at https://www.2carpros.com/first_things/engine_over_heats.htm

WATER PUMP
Removal
Disconnect negative battery cable. Drain cooling system. Remove accessory drive belt. Raise and support vehicle. Remove lower radiator hose. Remove nut on both front engine mounts. Lower vehicle. Remove generator. Disconnect power steering pump pressure hose. Remove cowl top vent panel. See COWL TOP VENT PANEL .
Disconnect water by-pass hose. Remove water pump outlet tube retaining bolt, and position tube assembly aside. Attach lifting equipment to left exhaust manifold. Raise engine approximately 5" (127 mm). Remove accessory belt pulley nut, and remove pulley. Remove generator support bracket.
Remove water pump pulley. Remove water pump bolts, nuts and studs, noting location of studs. Remove water pump, lower tube and gasket as an assembly.
Installation
Install gasket using Gasket & Trim Adhesive (D7AZ-19B508-B). To complete installation, reverse removal procedure. Lightly oil threads of bolt and stud not containing thread sealant.
If bolts originally contained thread sealant, clean and reapply thread sealant to bolts. Install studs into original location. Tighten bolts and nuts in sequence to specification. See Fig. 19 . See TORQUE SPECIFICATIONS . Fill cooling system.
Fig. 19: Water pump Bolt & Nut Tightening Sequence
Courtesy of FORD MOTOR CO.