I bought a 1993 Loyale.  Body is near mint condition.  The previous owner had some cooling trouble just before I got the truck to pick it up.  Long story short, the headgasket/s are blown.   I am re assembling another known good EA82 engine that I already had from another one of my cars.  But I need the intake from this 93 since it is the only California car I have. 

 

So I remove it, and the coolant passages are partially coated with crusty orange crud.  Some flakes off, some is very stuck to the aluminum.  I can't get at every passage - so what to do?

 

What could this be, I've never seen this kind of crud in a cooling system.  What might remove it?

 

I'll have to check the radiator and the heater core before running the car!

Mac's Radiator Cleanser found at NAPA stores is some great cooling system cleaner. I've left it in a few systems for longer than directions say to, seemed to clean things up greatly.