[jwhite1149]

Over the past few weeks I have flushed my radiator/engine three times with vinegar. Drained and flushed with water, refilled with vinegar, etc. etc.
Fresh vinegar has been in the radiator over 20 days. I have used 15 gallons of vinegar and 200-400 gallons of water.
I use a running water hose in the filler neck and refill the radiator with the engine running, hoping the fresh water will push out the rusty vinegar. The engine runs about 20-30 minutes each time I flush.
The rusty vinegar and water from the drain looks as if I have never flushed it before.
How much rust can a cooling system hold?
Should the water ever look clean and clear?
Should I, and will it help, to pull the heads and work on the block from the top?
I have new Drake water pumps and I think what I have done has helped.
What do you think?