I have a 2000 expedition with the 5.4L, anyway saturday and sunday it was -5 degrees and -21 with wind chill. I got up sunday morning and started the expy I let it idle for 15-20 minutes. I didnt have any heat coming out of vents but had to go to pharmacy, so I drove slowly 2 miles up to pharmacy and waited another 12 minutes for them to open. I let expy sit and idle the whole time. The temp guage was creeping toward the H but I still had no heat. Right when the store opened the temp guage hit the H so I turned off the engine. I got out and noticed coolant on the ground, so I opened the hood and seen that it came out of the overflow tank. I went in store for about ten minutes and came back out and drove 2 miles home and the temp gauge stayed in the middle where it normally sits. I figured the thermostat was stuck closed so I went to change it today. I went to drain some coolant out of the radiator petcock and it just dripped out. The coolant in the overfliw wasnt frozen. Its supposed to warm up in the fortys by wednesday. What are the chances I messed up the motor by driving it?

 

Did you ever check the antifreeze protection level?
You have to know this as winter comes in with low temps.
If there was no overheating in warmer temps, the coolant protection was not low enough in protection for winter time..
When water is added over time it dilutes the protection.
If you forget, this is the result.
Running a frozen motor that coolant cannot move in, will not melt in the radiator and not good for the motor.
Running down the road makes it even worse.
I would think you got away with it but learn the lesson.
Antifreeze chemical molecules separate the water molecules so that cannot bind together and change phase to a slush or solid.
Good luck.

 

I flushed the cooling system and changed the thermostat this last spring and put in a 50/ 50 mixture of coolant/ distilled water. It doesnt normally get that cold here and it has been fine in the cold weather we have had. I guess if nothing bad has happened I will have to adjust the coolant mixture. What doesnt make since is my car has the same mixture of coolant/ water and its fine.

 

your probably are OK and agree that the thermostat probably stuck. Couple of things pop into mind about this flush?
Did you put in a quality thermostat? Secondly, did you check the Coolant after you got everything topped off? Did you have all the little ***** or discs staying a float for "maximum protection"? Sometimes they will sink after a few seconds indicating a lack of protection.

Lastly did you get all the air pockets out after the refill?

 

I got a murray thermostat from oreillys. I checked the coolant it had three ***** floating. I let it sit and idle with the cap off and squeezed the top radiator hose, then took it for a spin and came back and let it idle some more with cap off. I bought a napa thermostat to replace the murray with. I figure if the coolant in the block was frozen the water pump wouldnt have wanted to turn.

 

50/50 is more than good enough for those temps. Keep in mind that pure glycol coolant will freeze, it's the addition of water that gives it the extended temperature freeze protection. Sounds strange, but it's true. Even heavily diluted coolant mixtures will help prevent freeze up. It will turn to slush, but that won't break anything. You may be looking at a head gasket or hopefully just a failed thermostat. Buy Motorcraft for this.

 

Was that 3 out of 3 ***** , or, was that 3 out of 5 or 6 *****???

Most antifreeze checkers have 5....if that was the case then....sadly to say you were not protected very well.

 

I've bought 3 thermostats at Auto-Zone and 2 of them were defective.
As to JUST 3 ***** floating,I agree..... your mixture was probably weak. I run only 60% minimum ratio,which gives you 60 below protection.
Those antifreeze testers,with the *****,can go bad. Best to have a good,more expensive tester handy to double check your results. don-ohio