I have a 1982 Stingray with a 3.0 that overheats under a load but goes back to normal at idle. I noticed that my riser was full of rust (alot of it....it kept coming out the more i banged on it). I knocked it all out and was hoping this was the issue. I also noticed a small amount of steam and milky stuff coming from my valve cover. It is also present in a very small amount in the side of the motor where the lifter galley is located (again, doesn't appear cracked either). I pulled the head and it doesn't appear cracked. No water in the pistons. No rusty plugs. I did notice that the number four cylinder intake port had rust in it. I didn't see any cracks in the intake/exhaust manifold. It is not in the oil pan (at least that I can tell), but the oil is seems less viscous. Not any difference in the amount in the oil pan either. I also pulled my lower drive and cleaned out all the rust debris. I changed the head gasket with a "metal" or "aluminum" one. Not sure what kind it is. I got it from Sierra. (but I did this before I realized the exhaust manifold was full of rust) Im so tired and frustrated chasing down the issue! 
:facepalm:
Question #1: Will cleaning out the riser fix the overheating?
Question #2: Where is the water coming from?
:facepalm:Question #1: Will cleaning out the riser fix the overheating?
Question #2: Where is the water coming from?
