Driving today and the truck (01 5.4) overheated, temp needle went all the way to red and oil light came on. I noticed a "whistling" sound coming from the engine bay. Shut it down and looked at the coolant tank. Coolant cap had "burped" water out of the tank and on to the intake.


I checked the oil. It was brown like normal, no signs of coolant mixture. I also opened the cap and cranked over the engine, no coolant spewed from the tank. No white tailpipe smoke, at this point I am thinking the head gaskets are OK.


I checked the fluid level in the tank, it was low. I added 5 bottles worth of water. I started it up and let it idle. The needle sat right in the middle. I let it idle 10 or 15 minutes. The needle never moved any higher.


Few other weird symptoms: over the past few weeks I have heard "gurgling" or swooshing sounds behind the dash. Like air is trapped and or moving in the system. It seems like all this happened when it got cold outside. This is the first time it has ever overheated. Also, the heater acts very weird. It will blow warm air for a minute, and then it will blow regular air. The coolant is the orange/yellow type. I have no idea how old it is. I also have no idea how old the radiator or thermostat is.


What would cause pressure in the system to blow coolant out of the 16psi cap? Could it be a faulty Tstat? Maybe a clogged radiator? 200k on this motor BTW

 

I would start at the t-stat myself. I would also drain all the coolant and flush the system very well before refilling with the type of coolant that is universal. Never mix colors unless it is stated on the bottle.

 

yeah maybe the Tstat got stuck closed??? Usually they get stuck open and the engine never heats up.


It's weird because I can hear the water moving around behind the dash, like it has air in the system.

 

This unfortunately sounds like a heater core to me. Replacing the tstat cannot hurt but I would have your coolant system serviced as well and if the problem persists, its a heater core usually.

 

possibly a plugged up heater core....since the heater is not blowing hot air...there are no leaks inside the cabin on the carpet. Maybe the heater core needs a good flush.