I have a 2003 F-150 with the 5.4 2 valve motor. Its got 105,000 miles on the clock.

Over the past several months I have been noticing intermittent coolant leaks at random hose connections. I talked to the parts guy at the dealership and he suggested that the expansion tank caps go bad, over pressurize the system and cause leaks.

I changed the cap and am still loosing fluid, intermittently. Brought it to the dealer today and they verified that the coolant was low, filled it and said it held a 20psi pressure test for 60 minutes. They put dye in the coolant and said to come back in a few days.

Not that I dont trust them to figure it out but they seemed puzzled. Any thoughts?

If i had to guess, I would say it is more prone to leaking when the motor gets hot.

Thanks

 

Intermittent leaks usually happen back by the firewall @ the heater core lines. An inline reducer that protects the core from high pressure burst is the one to look at. You need to catch it leaking to verify.

Keep checking for signs. Here's what you watch on an 03. As mentioned, lines in the back (toward the rear/passenger side head). Forward water jacket (intake/front passenger side cross over). Look at the water pump weep hole for signs , -also, take a flashlight, look behind the alternator/top of block in the valley, this can fill to a point with coolant if leaking. Lastly, feel the floor/carpet inside the cab, close to the firewall. See if it's wet.


So it's not puddling coolant on the ground?

Other than what's mentioned above, you could have a bad head gasket. Does she smoke at all ? White smoke , when you hammer the gas ?

After shut down, do you hear any gurgling while inside the cab? Sit and listen after shutdown for 15 seconds. Certain methods are sometimes used when she's not burping (no worries, not considered to be cruel lol).

 

Thanks J Brew.

The thing is I do see it leaking, typically from hose clamps. Ill tighten one, then the leak moves to another. But it doesnt leak all the time. its like the system is sometimes getting over pressurized. I have dealt with typical coolant leaks before but never anything like this.