This is with a 1998 5.4 V8. So after sitting for about a year, give or take, I finally got around to fixing up the 150 for a winter vehicle. Problem is, alwhenever the truck is in use there is a distinct antifreeze smell, white exhaust smoke, and the temperature gauge 100% of the time jumps all the way past the high temperature zone. The gauge is notable in that it acts this way even when the ignition is on, but the truck is off and the engine is cool. The antifreeze smell i cannot figure out because it doesnt seem to eat very much of the stuff that I've noticed. Finally, ive also got codes p1299, p0171 and p0174, and since I've begun runni g her more theres been a faint gurgling sound under the dashboard upon acceleration from a stop, behind the radio somewhere. I cannot for the life of me figure this out, the oil looks fine, coolant looks fine, and she runs ok, but I don't like the potential of overheating or some such hanging over me.

thoughts?

 

Do a cooling system pressure test. This will indicate of there is air getting into the system. Or worse, air getting pumped in from the engine.

 

I think you have a blown head gasket.