Hi I have a 2001 Ford Explorer that is over heating. I don't know what is causing it. I just replaced the radiator, water pump and the thermostat. It was fine for a few months then my girlfriend was driving it to McDonald's one night, which is only 1 mile from we're we live, and it started to overheat. When she pulled over and opened the hood the reservoir cap blew off. She said the engine was hot but not where it was smoking or anything. She said it wasn't even bubbling out the radiator cap or anything. When we got it home and it sat over night we tried driving it again and it did it again. We let it sit a few days and then tried it again, this time it didn't do it.

Long story but I'm on house arrest so can't really check it out but I don't really know much about cars, so if anyone could please give me some advice it would be great. Thanks for any help.


2 Answers 2


Three things I can think of which haven't been mentioned:

  • Check to ensure there isn't a plastic bag or some other debris which might have become lodged in front of the radiator. May seem obvious, but an obstruction like that can cause a huge reduction in cooling.

  • Get a new radiator cap. If the old one is not allowing for enough pressure to build up, this can cause issues. The point you made about "opened the hood the reservoir cap blew off" bothers me here. Unless someone is touching the cap, or it wasn't installed correctly in the first place, there is just about no way this is going to happen.

  • There are (or were) air pockets left behind in the coolant system which needs to be bled out. In most vehicles, the easiest way to do this is to park the vehicle on an incline pointing up, remove the radiator cap (when the vehicle is cooled down enough to not cause issues), then run the vehicle up to temp so air pockets have a chance to escape. Top the fluids off to ensure you have a full fluid load.

  • 1
    In my experience, radiator caps will frequently "die" under an overheating situation and need to be replaced. That is, if the radiator cap didn't cause the overheat in the first place.
    – ravuya
    Commented Apr 29, 2015 at 22:07
  • @ravuya - Very good points! Commented Apr 29, 2015 at 22:38

As DucatiKiller already said, probably too less coolant in your system. Check if the level is at "full" and definitely not anything underneath "low" on the indicator of the coolant reservoir. Depending on the area where you live, it's better to use coolant with anti-freeze in it. Take care not to overfill it though.

You could have a leak in the radiator or the sub-systems of it. Check if there is any fluid on your driveway. Coolant looks a bit oily when there is anti-freeze in it and you can really tell if its oil or coolant by smelling it. Have you hit anything on the bottom of the front with your car lately? This might cause a leak in the radiator if you don't have an engine bay guard.


Coolant has a higher boiling point than water. Do not use water as it will potentially boil and create air pockets of steam in your cooling jackets within the engine. Using coolant will ensure you are actually using liquid to cool the internals of your engine and prevent an overheating situation.

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