I have a 1998 expedition that runs fine then out of the blue water temp needle jumps to all the way hot. After i shut off the truck and wait a minute i restart and temp is fine. this happenes every couple of trips. i changed the t-stat and it still does the same thing. I hear lots of water running sounds while accelerating, but not at idle. The water can not cool down that quick so im puzzled. also one of the times the needle pinned hot i shut off engine, popped hood and upper hose was hard as a rock. that doesnt sound right. does it? I ran at idle with cap off and no air was purged. So im stuck dead in the water.........

 

The rock hard hose is a sign of high pressure in the cooling system caused by a blown head gasket.

 

what about all the other symptoms ? do they all point to a head gasket ?

 

It could just be a bad temp sensor giving a false reading to the gauge. The upper hose being hard isn't necessarily a death nell for the headgasket. It will be firm because the system operates under 12-15 lbs of pressure.

Is there coolant in the oil or oil in the coolant? Those would be indicators of a headgasket problem.

 

I am having the same issue with my 97 4.6 Expedition, I have bled the cooling system several times of all the air and I am still having the same result. I am pretty sure that it is the head gasket because when I pulled the oil cap off it was all milky at the bottom of the cap. Was the head gasket your issue and how much did it cost you to repair this? I hope that you got it taken care of.

 

This is NOT an indication of a bad head gasket, alot of that is just plain condensation. Pull the oil dipstick and see if that is milky, or better yet change your oil and see if it is a milky color, or pull off the radiator overflow bottle cap and see if it is milky in there. That will better determine a bad HG rather than looking at the bottom of your oil fill cap, as brand new cars can and do have that milky look to the underside of the oil fill cap.

 

It doesn't appear that the dipstick has a milky substance on it. The coolant tank looks fine. Could all of this be caused by clogged radiator, or a faulty coolant tank cap? I am at a loss, I'll have a compression check done on the car today and hopefully that will be the end of it. There is definitely some blockage, but I had Grease Monkey do a flush and fill. AHHHH I am at the end of my rope, hopefully the compression test will help me figure this out.

 

Here are some more symptoms that I noticed today, started the engine, everything was fine. Headed down the highway noticed that the air from the heater was getting cold. I pulled over turned off the engine and felt the upper radiator hose and it was cold and and very stiff. When I squeezed the hose I could hear a sloshing sound every time I squeezed the hose. I saw bubbles in the tank, I started the engine and still cold air and cold hose, I slowly and carefully unscrewed the cap on the tank, as it released the air in the tank, the upper hose got hot and so did the radiator. After the pressure was relieved the temp gauge went back to normal and the heater was blowing hot air, the top hose was warm and I could feel heat coming off the radiator. Then it ran fine. When I got to where I was going I turned off the engine and felt the radiator, and the heat seemed to be constant all the way accross, except for the very top of the radiator it was cold. I know that when air gets trapped into the system that it won't function properly, but my problem is figuring out where the air is coming from. I have gone through about 1.25 gallons of antifreeze in about a week and a half, so I am losing it from somewhere. When I got home I popped the hood I heard a hissing sound coming from somewhere near the firewall and the coolant tank cap was hissing some too. I still need to do a compression test on the cylenders to see if that could be my issue. But any new advise or tips would help.

 

your best bet would to get a pressure test done there are all kinds of hoses and pipes in the back of the engine that could be leaking if you want to pay for a compression test you should start with the pressure test

 

I'm having the exact same issue with my 2003 5.4 Liter Expedition. I'm thinking it's a blown head gasket too. I'm going to take it to my local high school (a friend of mine is the auto shop teacher there). They have a tool that measures hydro-carbons and we're going to check and see if it detects any at the Degas bottle. If so, blown head gasket confirmed. The loss of antifreeze on my vehicle is the cap on the Degas bottle. The pressure in the coolant system builds up so much that blows antifreeze out the cap.

Does anybody know if the head gaskets are a PIA or relatively straight forward job?