I have a chevy 4.3 vortec in a astro van. I was in the process of changing the intake gaskets(leaking) when i noticed that the left bank valve train was colored a light golden brown while the right bank valve train was bright metal like the day it was installed. Is this a condition of uneven heating in the block or head? Could this be due to the dexcool issues that “clogged” the ports and cooling paths.
One thing to consider is that fresh air enters the engine through one valve cover and that air, blowby, and condensation is sucked out the other valve cover by the Positive Crankcase Ventilation valve into the intake. If the engine is not producing a lot of blowby (sign of good engine), combustion products will not get to the fresh air side. So look to see if the hose from the right bank goes to the air cleaner and the hose from the left bank goes to the PCV valve and intake manifold.
Hope that helps.
Ditto what Researcher said. Further, that light golden color is perfectly normal and not indicative of a problem.