Clue number one: windows fogged when the car heated up.

Clue number two: I could smell coolant.

Clue number three: I found a small puddle on the passenger side floorboard.

Does this sound like a leak in the heater core? Is this a major or an easy one?

Anyone had experience?

It isn't easy to do, but you should try to get a look under the dash to see if it might be a heater hose or the heater control valve that is leaking. It could be something as simple as a bad hose. If not, then pulling the heater core isn't difficult, just annoying if you can't get yourself under the dash to see what you are working on.

You could try pressure testing the radiator, if you have a leak, it will be a lot easier to spot while there is pressure on the system.

Hopefully all you will have is a leaking hose.......

Wouldn't it be great if it was just a hose. So, how do you do a pressure test? Is it a matter of waiting for the car to heat up, or is there another way to put pressure on the system? Anyway, I will get in there and check it out. I do appreciate the help. Thanks.

A pressure test is done with a hand pump connected to a specail radiator cap that will pressurize the system. It would be a lot safer to do it this way than to have your hands somewhere you can't see and have them covered with hot antifreeze as antifreeze will stick to your hands and continue to burn.

Most any shop will have a pressure tester, or possibly you can rent them from an auto parts store or tool center.

Chance are that it is a hose leaking as most people never replace the short hoses on the heater core when they change the underhood hoses. The second most common place for a leak is the heater control valve, with the core itself being the last place it will probably be leaking. If the car still has the original hoses on the core and the stock clamps, my money would be on a hose leaking......

I put my money on hose/valve.Usually a core will leak on both sides since it sits on the tranny hump.I would suggest getting a valve and factory preform hoses and replace as a unit.Once one goes the others aren't far behind.Trying to use other than factory hoses will get you nothing but grief.Even if it is the core thats leaking.Replace the hoses/valve and you won't have to mess with for years.The coolant in your floor will eat/destroy carpet/clothes/paint anything it touches.Pull your floor drain plugs and wash it out.When removing the hose from the core,cut it off,don't twist it or else you may create a new problem.The valve is held in by 2 screws.I found if you get a long screw (of course the same thread)and cut the head off.Screw the "good"end into the rear mount hole.Now you can use that as a pivot to swing the new valve around to find the front hole.Of course that then becomes the pivot to find the rear now that the screw is removed . Havefun!!! Daniel