Originally Posted by ck94
But will it hurt it to drive it if it was something else??
If it is head gaskets and you keep driving it the coolant level will continue to fall. If it gets low enough before you catch it you will damage your egr cooler. If it's whistling and puking then there is a good possibility of a head gasket being failed. But once you put the new cap on take the truck out warm it up, pull over and relieve the pressure from the cooling system, tighten the cap back up, then accelerate safely at wot to 60 mph from as close to a dead stop as you can. Repeat this one or two more times, then pull over and see if your upper radiator hose is hard again. If it's hard repeat the entire procedure again. If your upper hose gets hard again then more than likely you have a headgasket leak. However I have seen a bad egr cooler show up as a bad headgasket. But yours is an 03 so I very highly doubt that your cooler is failed as I've only seen one of that style cooler fail. But before you tear it apart to replace head gaskets you should find a way to monitor your coolant temp and oil temp and make sure that once your coolant reaches 190*F your oil temp doesn't get more than 15* above that during a road test. Or just plan on replacing your oil cooler. And if you have to open your motor up I highly recommend flushing your cooling system with motorcraft vc-9.
If you want the flushing directions pm me your email and I'll send you a copy.
I hope I didn't make this too confusing for you. Just holler if you need anymore help.