Weird High Temp Reading

[rock3ralex]

I'm having a weird issue. Over the last 2 years I've dealt with replacing a coil hear and there. Recently I replaced 1 and during the replace my mechanic told me I was missing a large amount of coolant. They filled it with water in the mean time to check for a leak.

A few days later I was driving and I had coolant come gushing out of the tank all over the left coil over. I suspected a leak in the tank so I replaced it and the coolant.

Ever since I can't keep the coolant levels high and while driving the "High Temp Low Oil" indicator will come on, the temp gauge will max out the the computer will read reduce engine power though the engine will run fine. 10-30 seconds later the guage, reading and light will be off and back to normal.

Anyone have any idea what this could be? (no engine errors or codes)

Ride: 2003 Eddie Bauer 5.4L 242K Miles

 

[bedrck46]

Condition
The engine overheats

Possible Sources
Water thermostat.
Water pump.
Internal engine coolant leak.
Radiator.
Heater core.
Cooling fan or visctronic fan clutch.
Pressure relief cap.

CHECK THE HEATER CORE OPERATION
Install the pressure relief cap.
Key in START position.
As the engine starts to heat up, feel the inlet and outlet heater water hoses. They should feel approximately the same after three or four minutes.
Is the outlet heater water hose approximately the same temperature as the inlet heater water hose?

 

[stamp11127]

Never fill the new systems with just water and leave it in there for an extended period. Your asking for more trouble down the road.

How is the system loosing the coolant? Is it puking from the surge tank or just vanishing? Once you refill and start the engine do you see bubbles in the tank?

As far as the gauges go - one of two things - they are correct and telling you the truth or they are not. The gauge may be correct but the info from the sensor is wrong. This is where a "second opinion" comes in. A good scan tool will give you the temp reading from the sensor which you would compare to the gauge reading. I don't know if the sensors the Expy's use are the dual type, one for the ecm and the other for the gauge, or if they are separate.

Another possibility is that there is air trapped in the cooling system. When it has been refilled have you bled it?

 

[jdecker]

Mine was doing the exact same thing last week. I was sure it was the CHT sensor because the temp would go up and then fall to normal so quickly. However I changed the thermostat, simply because it's cheap and easy, and that seems to have eliminated the problem. So my guess is yours must be sticking closed like mine was.

 

[bedrck46]

use motorcraft t/stat

 

[rock3ralex]

Pretty sure it ended up being a blown head gasket. Ran a large bottle of blue devil sealant through the cooling system as per the directions. Been running great for the last 2 weeks. 242K and still chugging.

 

[whipper]

Mine does same thing only after cold start up then 10 min later goes to full temp over heat then I punch it and temp stay normal for the duration of driving. If I let it sit long enough to go clod it will do it again. Ive replaced T-stat twice,waterpump,2 rad caps. 5.4 03 super common problem. Everyones quike to say head gasket but the case with mine. thinking plugged lines? Hair goes cold with heat on just before this happens? Once temps go back down to normal heat returns. 6months and no one can find the problem.