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.

[40cpe]

Andy, does the Prep and Etch leave a black coating where it treats the rust?

[JHFORD51]

I'll add that I also tried evaporust on a operational engine. This was a 50 (about 4.5 gallons coolant capacity). Former owner had put in Al radiator and didn't use any zinc. I drained about a gallon of coolant and replaced with evaporust. I took several 20 to 30 miles drives over a two week period. Then I drained and flushed several times. A the time I also had a leaky thermostat housing so when changing I was able to look down inside the engine. Both radiator and head were much cleaner appearing when I completed the process.

[40cpe]

Thanks for all the ideas. I think I'm going to get the block checked and machining done before I spend any more time with it. I'm leaning toward soaking the coolant areas in Evapo Rust when I get it back. I can't see any more scale, just rust colored surface where the scale was. Most of the area is clean with a cast iron color. I just want to do a thorough job while it is all exposed.

Thanks again for all the suggestions and comments.

[B-O-B]

If you are get it machine & checked get baked & cleaned first.

[Andy69]

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Originally Posted by 40cpe

Andy, does the Prep and Etch leave a black coating where it treats the rust?

No, but it will turn white if it's not washed off. It should be dried quickly to avoid flash rust. If you dip and leave it to dry you get some limited protection from rerusting.