What would cause the vents to spray steam and water out of them and cause truck to overheat at the same time
Geezus ,,, short of hitting a Dragon ,,,the only thing I can think of is that a heater hose inside the firewall ruptured
I have seen a cracked heater core also cause this, something you can try is just bypass the heater core, a parts store can sell you the coupler and clamps you will need, then top off the cooling system and see if the problem went away, if it did then you know that you will have to replace the heater core, and thats not an easy job.
tennisshoes is correct regarding changing a heater core ... I would rather cut a truck tire into little pieces with dull scissors than change a heater core ...
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