My Ford F-150 started to overheat really fast after the last hard freeze we had.

There is definitely a coolant leak by the manifold, but I am thinking it is a hose because that's where most the liquid looks like it is coming from, but the overheating seems to be caused by something else. If I fill up the coolant and leave the truck sitting for about 15 minutes, it will start getting warm and all of the sudden the coolant retainer will overflow and it starts overheating.

Also, the heat will randomly start blowing cold air. It will be blowing warm air the first 10 minutes then everything after that will be cold air.

From my knowledge a coolant leak will not just instantly overheat your car, or do I have this wrong?

  • Welcome to Motor Vehicle Maintenance & Repair! Feb 28, 2018 at 18:43

1 Answer 1


I think you may have a couple of things going on with your Ford. First, the coolant leak has caused a coolant void (air bubble) in your cooling system. When your truck heats up to operating temperature, the thermostat kicks open and then the void allows steam pressure to build rapidly, causing the rapid temp increase.

You need to first find/fix the leak, then bleed the system of the air in order for it to stop behaving like this. This is the obvious thing which is wrong, so even if it isn't the cause, it still needs to be fixed. The idea is, fix what you know to be wrong. If it doesn't cure the overall problem, you still needed to fix this anyway and will help in the diagnosis.

If you are still getting a high pressure surge after you get the leak fixed and the system purged, you may have an issue with your pressure cap not holding the pressure it was designed to hold. As a separate item, this may need to be replaced.

If these two things don't solve your issue, you are going to be looking at larger issues, such as a blown head gasket which may have been caused by the over heating. I wouldn't go directly to this diagnosis, but it is a definite possibility.

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