As far as a heater core is concerned, I felt the floorboard and it is dry. If by "sweet smell" you mean a coolant type smell then yes, I most definitely smell coolant in the cabin. I think I will drain the radiator and refill it with coolant and water. Also how much coolant and water should I put in the radiator? Thanks
Edit:
I do not know when the pump was replaced. How would I check that?
What I would do:
1) I would go and either get coolant from your local dealer, the red stuff.
Or go get some 50/50 coolant, which has coolant and water pre-mixed.
2) You can fill the radiator to its limit, and then fill the reservoir to about halfway. (This helps avoid overfilling)
3) Start the truck up, and let the engine get to normal operating temperature.
4) Shut it off and let the truck cool back down for awhile.
5) Re-inspect the radiator for its fill line, as well as the reservoir. Fill the radiator back up and filll the reservoir to the MAX line.
And then I would keep an eye on it daily.
As for the water pump, if the vehicle doesn't have a maintenance record, then your best bet is to physically inspect it. Failing water pump gaskets, that seal the water pump to the block, can dry-rot and start leaking. The worst part about a failing water pump/gasket is that they don't show too many symptoms, other than disappearing coolant. You will smell a sweet chemical aroma. The engine burns the dripping coolant before it can reach the ground, so you don't see spills underneath your vehicle.
Also, you can get the coolant system pressure checked at your dealer or local mechanic. This way they can take the guess work out of it all. They could tell if its your water pump, radiator, head gasket, etc.
Good luck!