First off, i have a small timing chain cover gasket leak. Its not getting worse but does leak a bit and ive just been adding water every once in a while to the overflow because the actual radiator level isnt going down. It doesnt run hot, always at 195. So i pull off the cap today to check it and theres all this stuff on the cap and in the rad. Is it just rust because i've been adding too much water and not a 50/50 solution of antifreeze? Or is this some other crazy problem like tranny fluid leaking in, or oil or something.... And yes i know i need to get the leak fixed and rad flushed... i will as soon as I have some extra $$$, jeez.

 

Looks like rust, I know the freeze plugs are zinc plated steel, perhaps you've worn thru the zinc. The block and heads are cast iron and prone to rust as well. Old coolant actually breaks down and becomes corrosive, as could not removing all the flushing agent from a coolant flush.

 

fwiw- my rig was like that when I got it.. it took a while to get out.. I was concerned about freeze plugs, but those seem intact.. add to this, I mixed green and orange coolant, not knowing they would not mix well- and had a coagulated mess in the system.. and that took a lot of flushing to get out too..

when I pulled the intake to address the plenum, I could see the heads were orange in the passages as well.. I'd guess they still have remnants of that too.. after about three good flushes and two more drain and fills, it seems to be gone. (knock on wood)..

I was always under the opinion that the PO never did any maintenance on the truck, and I was paying for it.. the old coolant was well past spent, and then there was likely a high water content to the mix to boot..

 

Did you smell it ? Touch it ? is it oily ? Do you have oil shimmering in the coolant tank ?