Driving today and turned the heat on. Temp gauge says it's up to mid sweep, normal but no heat. No biggie. drive on 6 more miles, all of a sudden CEL light comes on. I look up the diagnostics on my Gryphon, and I've got the code for cylinder head temp. I did a quick look, looks like my Degas bottle was empty. I thought that was odd, but I can't specifically remember last time I looked at it. I let it sit and change my gryphon so I can see CHT. As I drive, no heat coming out and temps hitting 230's.After a couple minutes, heat starts working, temps come down to sub-210. It was still running fine, then all of a sudden she starts jolting and running real rough. I limp to a gas station, buy some premix coolant and add the whole jug. Gryphon showed code of CHT and CHT active. I don't see any antifreeze dripping or fluids leaking from anywhere. I checked my oil, it was a quart low but no water on the dipstick that I could see. No sweet antifreeze smell either. She starts up, running smooth and I get home and park it.
I will get a T-stat tomorrow and try that. Any other ideas? I have this dark fear of a head gasket problem. Help?
I will also change out radiator hoses and do all new coolant.

 

The running rough was it going into fail-safe. When the overheat reaches a certain point, the PCM shuts down every other cylinder in sequence to try to cool it down.

 

I figured that was it going into its limp home mode.

 

Well, there's a leak somewhere, that overflow tank didn't just empty itself.

There is probably nothing wrong with the thermostat except there wasn't enough coolant. I'd suggest monitoring coolant level closely for a reasonable period of time and gathering additional observations before deciding on replacing anything. A knee-jerk maintenance overhaul of the coolant system might well be premature and result in wasted time and resources from having to do things twice.

A cooling system pressure tester would be a good thing to get your hands on at this point.

 

Good call, projectsho89. I will top off today and keep a closer eye on things. I tend to jump to conclusions. I will keep you guys posted for more information.
Thanks!!

 

Not necessarily a leak - if the thermostat sticks shut and it overheats, it will boil and burp the coolant out. However, if this happens you will usually see coolant all over the engine compartment.

Any smoke out the exhaust?

 

It's been unusually cool here lately. I noticed some vapor the other day on cold start up, not smoke. It went away after driving for a few minutes. But no white smoke, no blue smoke.

 

Take a flashlight, shine it down behind the alternator in the the block cavity. Is it wet or holding coolant in the cavity? Is your starter soaked with coolant by chance.

 

I haven't seen any sign of that, but will double check tomorrow. Thank you. I added a gallon of coolant yesterday, and another gallon today. Scarey.
I have had this intermittent flute type whistle occasionally, usually after letting off the gas. I'm guessing a vacuum leak. I thought it was a pcv elbow i replaced last weekend, but it showed up again. That line that runs through the valley, what does that do? I'm assuming that's the line or source of a leak you are referring to? Is that a coolant line or vacuum line?

 

i think that line is for the knock sensor.

 

It's loosing that much coolant

You have a serious leak, - hope you have a motorcraft PCV valve in her.

Well here's the heater core hard line and knock sensor. This ones modded to eliminate the o-rings.

https://www.f150online.com/forums/me...+tube+mod.html .

Probably the best mod I've done, - do you know what you have to do to replace O-rings ?? Once they start going bad the inside of the tube corrodes and pits, - new rings don't last long...

 

Dry in the block valley, dry by the starter. Off work for the next 4 days, going to take some time to investigate.

 

If it's using that much coolant and you can't see any evidence of an external leak, the only place it CAN be going is out the tailpipe.

 

time for a hydrocarbon test? Wouldn't it be running like crap, down on power, etc?

 

One would think so. A spark plug read and a compression test wouldn't be a bad idea.