Help with overheating 4.6 4v!!

petemakmt said:

I recently purchased a 96 mustang cobra and the car was overheating so I flushed and replaced the coolant, but no help. Every time I drive the car for about 20 mins the engine bay smokes and theres hot coolant leaking from the reservoir. After some research, I am going to replace the thermostat but not sure how to tell if its the water pump or the thermostat thats the problem. I also made another post about my coolant crossover tube that needs to be replaced, so doing that at the same time would be efficient and some help on that as well would be very much appreciated.

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I’d replace the thermostat first as it’s a much easier task than replacing the water pump.

4Vs have a specific process to filling the coolant, due to the complexity of their coolant layout. If you just added it to the tank, you probably still have air in the system. 4V Coolant Refill Process

Thermostat isn't a terrible first step; certainly a cheap/easy thing to try. I would think if the crossover had failed, you would see it leaking; it's literally just a metal pipe with a few fitting. Water pumps are pretty easy to change on these cars as well, though you might pull yours and inspect it; they're not a terribly common failure point, and a new O-Ring is only a few bucks.

You might also check your fan; I had one fail to come on and cause what you describe.

If none of that is the case, you might make sure it doesn't have a blown head gasket. Overheating that quick is kind of extreme.