Cleaning rust from water jackets.

[Andy69]

Originally Posted by 40cpe

I had a block dipped at a former Redi-Strip franchise. They don't go by Redi-Strip anymore, but are a commercial/industrial metal cleaner. When I got the block back I could see that here was some rust scale in some areas of the water jacket, while other areas are clean. I chucked a piece of 3/8" stiff guy wire in my drill and went into all the holes around the cylinders. Then I used a piece of stiff steel wire about 1/8" and went in between the cylinders and the exhaust passages. When I turned the block on its end there was a double hand full of rust and scale fell out. I'm confident I can't reach any more with the limited access but I know if I got this much out there is more. What is the prudent action to take? I've read good things about Evapo-rust and am considering putting the block on the engine stand so I can level the deck, block the water pump holes, and soaking in the Evapo-rust.

I would go to Home Depot and pick up a gallon of Prep and Etch. It's the same as Right Stuff, Metal Ready, Ospho, whatever. Basically a phosphoric acid solution. Get a tote large enough to hold at least half the block, pour in the P&E, fill the rest of the way with water, dip, and leave in for 10 minutes and check. You might need more time depending on how much it's diluted. I;'ve had good luck derusting parts this way.