Hey there, I have a '97 F150 4.6 V8 Ext. Cab.

Recently I have been having a problem with my cooling system. I do not know what the problem is but, when after ihave been driving 2.5 -3 miles, the gauge for the Radiator Sky rockets to borderline "redzone". It runs at the mid level temp wise. I have had this problem about 4 or 5 times in the past week. My coolant is at a good level, so I don't know what is causing the "overheating" considering it is not heating up, I have been told that it is the thermostat, or possibly the radiator cap. Any suggestions? or Tips? As is probably evident, I am not too well-versed when it come to repairs on my truck.

Thanks for any help!

 

Do you mean the temperature gauge goes to red & then goes back to normal range? If so, change the thermostat.

 

yes, that is exactly what it is doing.

 

Sounds like the thermostat is sticking, don't take a chance, put a new one in. Not that expensive, but if it fails closed you could do serious damage. Your cap's probably ok if you're not losing coolant, but you can get it checked, they're not that expensive either. By the way, how long since you've changed the coolant? If it's been a couple years or more, change it also when you put the new thermostat in. Let us know if that fixes it.

 

New thermostat is in, all appears to be well now! Thank you!

 

You're welcome, that's good news!

 

I have a 2000 Expedition 5.4L which seems to be having a similar problem. I purchased it last July and never had a problem with cooling all summer. Now, this fall, I had two instances where if you take the vehicle out on the highway without plugging it in or warming it up, it overheats very quickly. The first incident I did not stop and after a few seconds in the red , the thermostat obviously opened and everything went normal. The second incident, I thought that I would keep driving but after driving with it in the red for just a few more seconds it set the Service engine soon light and put the truck in fail safe mode. I immediately pulled over and turned it off. After waiting a few minutes and making sure I hadn't lost much coolant, I restarted it and it was all normal except for the Sevice engine soon light? Another symptom of the problem is a lack of warm air in the cab. Two things confuse me. Why would a thermostat stick shut in cooler weather (around 30 degrees F) and not when it is warmer out. And why would I not get warm air in the cab long before the thermostat releases? Are the heater cores downstream of the thermostat? What is also bizarre is that if I plug in the block heater for about an hour before I drive the vehicle everything is normal (ie. warming up the coolant seems to prevent the thermostat from sticking). What gives?

 

I would definitely change the thermostat. The lack of warm air in the cab is confusing, could you have air trapped in system? Otherwise doesn't make sense. Does heater work ok with temperature at normal? I would change the thermostat & make sure cooling system is full, bleed air out,( not sure on your rig, may have to unhook a heater hose to get all the air out).

 

If I plug the block in for minimum 1 hour, and then start the vehicle, I start getting warm air within 5 minutes, which I believe is the way it should work. The temp gauge in this situation is just starting to rise and continues to rise to the middle normal range(and I have lots of heat in the cab). When I don't plug in the vehicle in this cool weather and I start the vehicle for the first time of the day, the temp guage in the vehicle starts to rise but there is no warm air in the cab. If I drive at highway speeds I get the overheating as described before, yet there is still no heat in the vehicle. It seems only when the thermostat opens does everything turn normal. And after that the vehicle is normal for the rest of the day. It seems to exhibit this weird behaviour only after sitting overnight without plugging it in. (We are having typical cool weather this fall, but it's going to get a lot colder and I shouldn't have to be plugging in the block heater yet!) I am going to change the thermostat out, but I not convinced that the problem will go away. Hope so, though. I don't think there is air in the system, but I don't know for sure. Is there any way of checking?

 

If one of your heater hoses is the high point in the cooling system, you could loosen it to check for air.

 

After changing the thermostat in my 2000 Expedition with no good result (ie. it continued to overheat on the first time of the day...see my previous explanation), I took it to a non-Ford shop. They replaced the water pump and thermostat (both parts were not Ford approved parts, but I didn't think it mattered, and in the end it didn't). This still did not fix the problem. Finally took it back to the Ford dealership where I bought the vehicle (had been avoiding them because of no warrranty and $100 per hour shop rate). Even though, I advised them that the pump and thermostat had already been changed and the only logical reason for overheating that was left was a headgasket problem, Ford again changed the waterpump and thermostat to Ford approved parts. This made the problem worse. Finally today, they put some chemical in the antifreeze that turns blue when combustion gases leak into it...and guess what it turned blue! So now the head gasket will be changed. Very reasonable, though as the vehicle was bought in July with 120,000 Km and only a 30 day warranty, Ford offered to pay half the cost of replacing the head gasket and I get the water pump and thermostat for free. They have quoted me about $1200 Canadian for the head gasket barring any other problems when they get the engine apart. This whole experience has taken approx. 2 months to resolve but I should get my vehicle back in a couple of days. I would not hesitate to deal with this Ford dealer again as I think they have been very reasonable. They are Moose Jaw Ford, in Moose Jaw Sask, Canada for anybody that's interested.