04 Explorer. Het comes and goes and so does engine overheat light says oow oil

[Hoguens heroes]

I just bought this truck a week ago. It was blowing hot air. Now it blows cold ,then hot,then cold..NOW the engine overheat low oil light is coming on and the temperature gauge will shoot up for like 30 seconds then drop back to normal...WTH is going on?

 

[Tech By Trade]

Air bubble under the thermostat? Tried burping the system?

 

[boominXplorer]

Check fluid levels?

 

[Hoguens heroes]

Air bubble under the thermostat? Tried burping the system?

I have not. Will that help? How do I burp it?

 

[TechGuru]

Bubbles getting into the coolant is usually a sign of a head gasket leak I'm sorry to say.

 

[07gtman]

The plastic coolant container under the hood, take the cap off while its cold and start the car let it run until its hot, if the coolant is low add some to the hot level, Let it run a while longer 5/10 mins watch for bubbles in the coolant tank and the level to drop again..watch for the next 100 miles or so and see if the level goes down..if it does and you dont see a leak good chance you have a head gasket issue..

 

[Tech By Trade]

If you ran it below the thermostat, due to a cracked rad tank, and filled it back up, it leaves an air void between the thermostat and the fluid. This void wont allow the thermostat to open causing heat issues. that's why when changing a thermostat or rad, I will usually top the block off before installing the thermostat and housing, then top up the rest of the system. Some people say you can just pressurize the system and compress the upper and lower hoses repeatedly but I have never had much luck with that.

If you start the truck, and let it warm up with the rad cap off, and notice bubbles in the rad you have a cracked head, or blown head gasket. The old 300's were notorious for this. Whenever we are looking to buy a used one for the farm this is the first test we run on them.