I think the heater core on my 1993 940 is leaking. (just another leak in the cooling system). It seeks that as soon as I get one leak fixed in the cooling system another develops in another part. I recently had the head gasket replaced and almost as soon as that was done I notices some coolant on the floor mat (front passenger side) and a distinct odor of coolant in the cabin. I also noticed lower coolant levels in the reservoir tank and need to add coolant almost daily. I have used a sealer in the cooling system with some limited success (at least it slowing the leak some). How hard is it to replace the heater core? Is it something that I should be able to tackle myself? I can obtain a replacement heater core for reasonable price but want to determine if it is something I might want to do myself.