Hi all. I'm at my wits end with this truck.

2003 Excursion V-10 Limited.
195k miles.

So this all started about a year ago. The truck was needing antifreeze about every few weeks or so. My primary vehicle at the time. It would smoke a bit on startup, but once warm, it would run fine. Ran rough at startup, but once warm, was fine.

Didn't think much of it. Knew it was probably a head gasket or something.

So as time goes on, suddenly the truck would loose heat and burp out antifreeze. I would shut off the truck, wait 1 minute, turn it back on and the temp would immediately go back to normal. About a half-gallon to 1 gallon of coolant came out.

Thermostat, right? Wrong. Didn't fix it. So we did a flush of the coolant, found an elbow into the heater core was leaking. Thought that was the culprit of all problems. Nope.

So, lately I will fill it up with coolant, drive 5 miles, it overheats, burps coolant, turn it off, wait 1 minute, start it up and it's back to normal temp, and can drive for a day. But as soon as I top off the coolant, burp and back to normal.

Now one weird thing that I've been telling the mechanics with deaf ears, is this. If it's quiet, I start the truck and can hear gurgling sounds from behind the dash on the passenger side. Heater core location?

Mind you all, I am NOT a mechanic. And I'm at a loss... Help?

 

Hopefully your oil is clean and not a milkshake?? I would pull the plugs and check for crystals. Its a sign of burning coolant. you may be pressurizing the cooling system from a cylinder which means head gasket or cracked head (between valves). You should have someone do a cylinder pressure test, AKA compression test. Just covering basics. Hope its something simple and cheap.

 

Oil is clean. Which leads me to another test that I forgot about. A pressure test was done. Didn't loose any pressure while cold and sitting, but when started and warmed up, pressure went down. Which we think that it might be a cracked head. Do you think that would pressurize the system causing it to overheat and then go right back to normal temperature?

 

Cracks can do strange things, open up when heated, or close, and vise versa when cooled down. Depends on where it is.

Did the pressure go down in one or two (adjacent) cylinders?...or overall?

 

I'm not sure on that.

 

Moved to the 6.8L V10 forum.

Stewart

 

Sounds like compression leaking into the cooling system, filling up the heater core with "air" and causing your issues.

"Burpring" that much coolant, it's gotta be cylinder compression leaking into the cooling system. The pressure gets up to a point, and it exceeds the cap's rating, and BURP.

Isn't there a test kit to check for exhaust gases in the coolant?

 

Sounds like they did a coolant pressure test and not a leakdown or compression test which I believe you are referring to.

Agreed with this, head gaskets may be in OP's future.

 

Had the same issue as the op. I have started to disassemble my engine. Pulled one head and found it had a lot of carbon and some rust on pistons. Check my post on head gaskets on the excursion forum

 

Here's the latest.

Replaced the thermostat.
Replaced the radiator and coolant overflow tank after finding a crack in tank.
Replaced upper radiator hose.

The radiator was replaced because the upper radiator hose was collapsing.

So now, I drive 5 miles or so, have heat, then heat drops out. I stopped and the upper radiator hose was cold. no circulation. Plenty of pressure in the upper hose.

They want to throw K-Seal into the motor. I said no. Would a head gasket stop the coolant from circulating?

 

And, to add that if I leave the truck running, it will overheat, burp the coolant, then all is good. Until it decides to do it again.

 

You are losing coolant either throw a pinhole leak in a hose or radiator, intake manifold leak or head gaskets are shot.

Do you have excessive white smoke from your tail pipe?
Have you leakdown tested the engine?
Compression tested the engine?
Pressure tested the cooling system?

 

Mine had the same symptoms. I changed my head gaskets and it cleared up. New head gaskets have about 50 miles on them. I can update when I get a thousand