Flushing the Block

Thank you sir!

To be clear, the filter will not clean up a block like the one in the pictures, it will keep it from happening again after you have mechanically cleaned out all the rust that you can. Once it has got to the point the one in the pictures is at the only way is to pull the core plugs and use high pressure water/air to blast the loose rust and muck out.

I didn't look closely at the pics until now, I though that was the outside of the core plugs, not inside them! Wow.

Discussion on Yesterday's Tractors brought up using powdered Cascade dishwasher detergent with Dawn soap included-I'm thinking a caustic detergent and oil emulsifier- as a flush.Caution with multiple dissimilar metals as in newer cars. Most of the old tractors and trucks don't have aluminum blocks or radiators, so maybe it wold be okay...?

I've never been a fan of chemical flushes. What you want to remove is what is shown in the pictures, Chemicals can't do that, they may be able to etch the walls, but without removing the sludge that fills the bottom it is a lost cause.
Clean the sludge out, and install a filter to remove the rest. You can tell when a filter clogs because it will remain cool while the rest of the system will be warm.

Only thinking there, on the Evaporust (which does work well)(and would sit in there, not flushed) would strip all the rust and give it a blank slate and just maybe, loosen a bit of the hold on smaller particles that will be flushed out with the water and air flush.