Overheating

[Canyon Man]

Hello Boys,
So here is my problem. 2000 ford Expedition 5.4 is overheating. My coolant reservoir was only a bit low. I would drive it a few miles and the temp gauge would peg out. I would then wait about 5 min temp would be in the middle range and peg out in less than 30 sec when I would start it up again. I am blowing heat from the vents so my water pump is circulating.And after 30 miles of this cycling I never lost any more coolant (I had to get home from work). When I would pull over to the side of the road I could easily pull off the radiator cap and nothing would boil over at all. So could it be the sensor in the head? Maybe faulty? I didn't notice any unusual smoke from the exhaust. The truck does have 250,000 mile on it though.
Thanks for any help

 

[69Hcode]

Might be a stuck thermostat

 

[Canyon Man]

If the thermostat was stuck I wouldn't be getting hot air from vents, correct? Because with the heat on I am getting hot air.

 

[stamp11127]

Easiest thing to do would be to check the temp of the upper radiator hose, lower radiator hose and across the radiator. An ir temp gun is a good tool for doing this and cheap ones are under $40. You would be looking for cool spots on the above items.
Depending on the mileage I would consider changing the water pump just as a maintenance item & change coolant. If you mix your own make sure to use distilled water and not tap water.

 

[Yudaman]

If the thermostat was stuck I wouldn't be getting hot air from vents, correct? Because with the heat on I am getting hot air.

Wrong.
Ford uses a bypass from the upstream side of the thermostat to the heater core and then back to the water pump.
Change your thermostat.

 

[greasemonger]

When mine did this it was the water pump. Service tech showed me that my oem impeller fins had completely rusted away, thus not moving anywhere near the amount of pump action needed at speed. Cheap fix too and hasnt gone over 1/3 on the gauge since...but also change the tstat.

 

[Canyon Man]

Thanks a lot guys. I will check it all out this weekend. But I did change the pump and thermostat about 2 years ago

 

[IMINYOURCHAIR]

Thanks a lot guys. I will check it all out this weekend. But I did change the pump and thermostat about 2 years ago

thermostats fail... I usually go with what is called a "superstat" by stant. never had one fail but if they do it will stay open as a fail safe..

 

[Canyon Man]

Awesome. I will put that in

 

[Bedrck47]

Thanks a lot guys. I will check it all out this weekend. But I did change the pump and thermostat about 2 years ago

A lot can happen in two years

 

[Canyon Man]

Ok, so I put in a new thermostsat and it is still the same but at least now I can give more details. I hooked up my computer to the truck and the temp gauge reads 259 deg f. The upper radiator hose reads 130 and the lower 85 deg. I am waiting on my water pump,should be in tomorrow. I think it may be the water pump....Any thoughts?

 

[Bedrck47]

Thanks a lot guys. I will check it all out this weekend. But I did change the pump and thermostat about 2 years ago

As I posted earlier A lot can happen in two years.

From the temp readings you posted sounds like your on the right track.

After you change the pump kindly take the temp reading again and post them. May be good information for the next person

 

[IMINYOURCHAIR]

+1 on the water pump. see if you can get some pictures of the impeller too if it turns out to be the culprit.

 

[Canyon Man]

Sure thing guys. Anything to help out the next guy. My water pump just came in. I will be starting this in a few

 

[Canyon Man]

Well all done but I had to drain all the anti freeze. So I filled it up, 2 gallons, started it up and within a few seconds...30..it was overheating.I have been adding more coolant as the reservoir allows. I figured since I drained it all, there is no coolant yet in the heads. So I am going to wait an hour or so and give it a shot again. BUT... I don't think the pump was my problem. The pump I removed was nice and tight, no play in the bearing and spun nice and smooth. But I will know in a few hours one way or another. Maybe the radiator is plugged. Don't know yet...............

 

[stamp11127]

What are you using for coolant?
What was the blocks condition when you pulled the pump?
How soft is the lower rad hose?
Did you bleed the air out of the system?

 

[Canyon Man]

What are you using for coolant?
What was the blocks condition when you pulled the pump?
How soft is the lower rad hose?
Did you bleed the air out of the system?

50/50
looked fine
very soft...no pressure
best I could.. parked on incline and left cap off . but it only runs for less than 30 seconds and goes into hitemp mode. Even now 2 hrs later I just turn the key and the temp gauge immediately pegs out to High with out even starting it. And when I did start it it went to hi-temp mode in 10 seconds after being off for 2 hours. I even disconnected the battery for 20 min thinking that might have something to do with it but nothing.

 

[stamp11127]

Which engine do you have?

The 5.4 has a cylinder head temp sensor that doesn't show being on the 4.6 according to the diagrams. I would verify the engine coolant temp sensor or cylinder head temp sensor is operating correctly.

If you have an IR Temp gun I would take readings of the heads, rad hoses and across the radiator.

I doubt this is your problem but hoses shouldn't be soft but firm to the touch. Under some circumstances the water pump can collapse the lower rad hose cutting off the flow of coolant.

You didn't state seeing bubbles in the overflow tank while running so I'll assume you haven't blown a head gasket.

 

[Canyon Man]

It's a 5.4. I know what you mean with the hoses but that's not the problem. It would have been an easy fix. I have been working on this for 10 hrs today...Time to walk away, regroup,relax,get liquored up and hit it again tomorrow. The sensor you are talking about is located under the intake manifold. So that may be another thing to check out.This is quite perplexing though. Nothing like a challenge

 

[Bedrck47]

not to insult you. But are you sure the t/stat is installed properly?
also have you tried running it without the t/stat and checking the hoses