I have been battling a problem on this truck for a while now and need some help. My Excursion started overheating back in August and the symptoms were extremely weird to me. I was driving and all of the sudden the temp spiked and the truck went into a limp mode with a CEL. Code was for Cylinder Head Temp and you could definitely smell the hot coolant. I let the truck cool for a bit and started driving again, only to have the same thing happen. Quit driving it for a bit until I could check it out and replace a few parts. Replaced the thermostat and res cap, and it drove great for a while. I have now found the reason it ran good was because I had the heater on. Any time I drive without the heater on it will again randomly overheat, however if I pop it into neutral, shut the truck off, start it back up, and continue down the road it does just fine. CEL goes away after a couple miles and it doesn't act up so long as the heat is on. With that, the heater definitely does not put out the heat I am used to in other ford applications and it will only heat up every once in a while when you hear a small amount of coolant drain into the heater core. I would assume this is connected since the heat must be on to stop the overheating issue.

My question for you guys, any ideas??? My current thoughts are to replace the heater core, the control valve which lets the coolant into the HC, and possibly replace the radiator/fan clutch. Could this be a more serious issue like a HG?

 

Before spending money on random parts, pull the control valve and inspect it. It may be that debris or deposits have it doing something weird and the part seems directly related to the problem.

 

I will check that this weekend when I am able. Anything else I should look at?

 

OK, so if you are hearing splashing from the heater core, that also means you likely have air in the system as well, did you vacuum fill it or at least burp it really good to get the air out? It can help the burping process if the front of the truck is jacked up or parked on an upward incline, i drove mine part way up a pile of dirt so it was like a 30 degree angle, and that majorly helped get the air out of the cooling system.

Also, if the heater helps cool it, the control valve is definitely worth checking out like @BassFantasizer mentioned, but it should not be required for this, i would strongly recommend with a warmed up truck, go down and feel the radiator cores from bottom to top, if the bottom cores are not hot, but the top ones are hot or really hot, you need to replace the radiator, those little cores get clogged up with sediment and gunk out of the system over time, until less and less of them actually work, and you slowly loose cooling capacity.

My 96 GT had this happen, kept getting hot and could not figure it out until i shut er down and felt down the radiator and realized the bottom center was barely warm and the top was scorching, it was plugged up bad. If it turns out to be the radiator, i know where you can order online an all aluminum radiator, no plastic tanks, for like 400 bucks delivered, without the plastic tanks, they live a lot longer...

 

I have tried to burp the system several times to no avail. The radiator does have small differences in temp but not crazy. I’ll try and get actual numbers.

 

It could be the headgasket.

I had an overheating issue on my Sienna. I went thru and replaced a bunch of parts, but the issue was a VERY SMALL leak in the head gasket. It would put air (from the combustion) into the coolant. A very little at a time, but over the long haul it caused the engine to puke out a lot of coolant from the expansion tank.

Unfortunately it wasn't cost effective to fix it.

I hope this isn't what's happening to your X, and you could have it pressure tested to verify.

Sweet rig & Good luck!

 

Alright so it has been a while, and it still has the same issues as previously mentioned. I have had the radiator tested to see if that is the issue, mechanic said it was fine. I have done 4 thermostats, still not any better. I am thinking it couldn't be the thermostat because I have on multiple occasions worked it with 6K loads through the Colorado mountains with zero issues after the initial warm up for the engine.

The only new thing to report is the engine has next to no coolant in it when it throws the code and puts the truck into limp mode. If it was an air bubble, I think the 5 or 6 times I have had to replace the coolant it send out the overflow would have fixed the issue. I used a large funnel to make sure it was able to burp, and parked on an incline to no avail.

My question now, has anyone had similar issues? Any random parts to check out? I am looking for whatever suggestions you guys have, because I am completely at a loss.

 

I know of only one thing that could cause this, because i went through it myself on a different motor.

I had the same problems when a vehicle had a head gasket in which there was seep between the cylinder and the water jacket.

under heavy load gases from a cylinder push through the gasket into the water jacket a little at a time, and as they do, they displace water into the overflow, which eventually fills and overflows out of the bottle, and eventually you end up with too much gas/vapor in the cooling system for the water that left to effectively flow through, thus it overheats, and you find later that its also low on coolant.

I just typed all that out and had not read that @XxDesmoxX said the same thing pretty much, a compression test may confirm it also, if you compression test the cylinders one by one including a bleed down test, i bet you find one cylinder, possibly more than one, that bleeds down noticably, and as it does, you see the overflow bottle bubbling....

IF you decide to do head gaskets, its Fel Pro or bust, and clean all the surfaces really really well, when you think they are good, do them again, and then you should be good assuming nothing else was wrong... Since you would have the heads off already, might be a good time to do a timing set, and possibly the valve train too, depending on your preferences and budget.

If i go into a motor for something, i go all the way in, but thats just me. I have seen the guys who dig it all apart, and replace just the 1 thing that failed, then something else fails, XD.

 

^^^This^^^

My V10 was doing the same...low RPM I'd get overheat warnings, higher RPMs it would go down. Found out I lost the fan clutch. Since it was easy, I replaced it, the water pump, and the thermostat but the issue remained. Had a shop block test it and they found exhaust gasses coming out of the expansion tank. Put in that head gasket sealer to get an extra month or so out of it to save up for a new motor.

After the motor swap, I was still getting overheat warnings on the dash but no SEL light and no fluid loss, and the SCT wasn't showing any issue with the coolant temp. Shop kept struggling to figure it out. Mechanic claimed he drained and put in new radiator fluid like 4 times to ensure there was no bubble and tried to charge me for the fluid (told him he was an idiot if he was throwing out radiator fluid with 5 miles on it and refused to pay). I kept asking if he tried replacing the sending unit and he said that wouldn't be the issue. On day 2 of the 2nd visit back to his shop I finally demanded he do it, problem went away with the new sending unit.

I hate to say it, but this sounds a lot like what I had (maybe not the fan clutch, but the overheat/head gasket bit). I'm seriously hoping that's not the case for you.

 

For like $40 you can test the cooling system for the presence of combustion gases and know for sure, without guessing, if its the head gasket or not.

Plenty of test kits out there for this, below is a link to just one cheap example, but there are plenty of others if you google "combustion gas leak detector"

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