Unfortunately I lost the block heater out of the right rear freeze plug while going down the freeway today. Needless to say all the coolant came out lol before I could shut er down, she was reading about 240 degrees on coolant temp . Shut it down and assess the situation, found the block heater dangling by the starter lol. Got it cool back down to 200 and had to drive it a few more miles before I could safely get a new heater in as well as fill the coolant.. Ok now the fun part it only took a gallon and a half so far now the thermostat is not opening, with the radiator cap open while the engine is running I have no air bubbles coming out like a popped head gasket . I have got the temperature back up to 220 before I will shut it down because I have no heat coming out of the vents and heater core lines are stone cold. To me it is either the thermostat got hot and welded shut from being hot or the water pump failed, have any of you guys ran into this issue after an overheat?

 

I'm pretty sure coolant should always be flowing through the heater core, even if the thermostat is shut. Sounds like you have a water pump problem, which perhaps caused the overheat, and if the radiator cap wasn't working correctly, it might have been possible that the pressure buildup popped out the block heater?

Normally when water pumps fail the seal goes and they leak. Sometimes the impellers break off or wear down and they don't pump anymore. I'm not sure if you could figure any of that out by just taking the belt off and spinning the water pump, but it can't hurt to try.

 

Had a huge air pocket, total coolant added was 7 gallons plus the Ford diesel coolant additive. Long story short I wanted to replace my block heater anyway because it would leak from the o-ring sometimes and I was wanting to do my winter coolant service, lol it just made me do it sooner

 

I wonder if your bypass is plugged? Even with the t-stat closed it should have allowed that air to bleed through.

 

Possibly, I was thinking about that this morning actually. After finally being able to fill with coolant I drove it pretty hard for about 5 miles and my temp stayed 200*, just because I think I'll pull the thermostat this weekend to check everything out. Just was a very odd experience last night, knock on wood this is the only failure/issue I've ever had with this truck

 

i wouldn't touch it at this point.sounds like you got it purged just fine anyway.
an easy way to test the bypass ball,is to simply squeeze the upper rad hose when cold/not pressurized.you'll hear it clicking as you squeeze and release.good to go.run 'er.