New Radiator, Now Leaks
 

I just installed a new radiator in my 82 300D. I took this opportunity to flush my cooling system and drain the block etc. Some chunky stuff came out of the block drain plug when I was flushing the system out. I replaced the thermostat and my hoses. Now the car is leaving a coolant spot on the road on the passenger side towards the back of the engine every time I park it. I can't see where it is coming from. None of the hoses are leaking. I did start smelling coolant when the heat is on. I am thinking that the heater core is leaking. If it is where is it draining through? Also I really don't want to use the pellet type stop leak or anything since it is a brand new radiator and it is running great now. So my questions are:

How hard is it to replace the heater core?
Where could the leaking coolant be draining to get outside the car?

Thanks alot for the help.

Are you sure the block drain plug isn't leaking? I belive a leak in the heater core would end up draining out through the AC drain abouv the transmission. I would crawl under the car and see if you can tell where it's coming from.

Sounds like the drain plug is leaking. Did you use some thread sealant when you reinstalled the plug? Give it a little tweak with your wrench.. might be all it needs.