For years my 5.9 has been losing anti-freeze coolant and I haven't been able to find where the leak is. Yesterday, after the shoveling snow, I had a thin layer of clean snow under the truck. When I pulled out after about an hour of the truck sitting there, I saw small drops of AF along the exhaust system and the front of the muffler. The drops were too small to normally see on the road or driveway but the green from the AF showed up real easy in the snow.

The loss of AF is slow. I have to fill the expansion reservoir every couple of months. I don't see any overly obvious white smoke coming out of the tailpipe, there's no sign of AF in my oil and my truck runs great. I'm suspecting the heads might have a crack or a blown head gasket. Any other ideas?

 

check all of your freeze plugs and around the timing cover gasket for coolant. if the engine is dirty in those locations then clean it all up and check again after the next time you run it.