My '99 F150 has had a coolant smell in the cab, which seemed to get worst with the heat on. Today I drove it home, parked it, and went outside later to find a decent size puddle of antifreeze. The early symptoms seemed tipical of the heater core but the floor in the truck never got wet, and the heater core was replaced 3 or 4 years ago by the previous owner. I got under the truck and looked and can't see where it's leaking from, but it's dripping off the heat sheild for the exhaust. Will a bad heater core leak outside of the cab? Thanks for the help.
Hmm, I actually replaced the alternator wednesday and didn't notice any coolant, but I'll check again today. If I don't see anything I guess I'll loop a heater line between the motor ports and bypass the heater core, that should isolate it to a motor leak or heater core leak. Thanks for the replies - Jake