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Technical Cleaning the block

Discussion in 'The Hokey Ass Message Board' started by ekimneirbo, Mar 27, 2020.

  1. ekimneirbo
    Joined: Apr 29, 2017
    Posts: 1,085

    from Brooks Ky

    I have removed the heads from a 50 year old Cadillac engine and the short block is sitting on the stand till the Corona goes away and I can take it to a machine shop. I'm kinda anal about trying to do things right, and I want to get that 50 years of rust buildup out of the block before having it professionally cleaned. I'm thinking about sitting it in a 50 gallon drum submerged in a caustic solution and building a small fire under the drum to get it boiling for a few hours. Anyone tried that or have a better suggestion?:rolleyes:
    Last edited: Mar 27, 2020
  2. Hemi Joel
    Joined: May 4, 2007
    Posts: 821

    Hemi Joel
    from Minnesota

    Last edited: Mar 28, 2020
    ekimneirbo likes this.
  3. :D
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  4. alanp561
    Joined: Oct 1, 2017
    Posts: 1,046


    I've had real good luck with a 55 gal. drum and 10 pounds of citric acid. The acid costs about $25 on Amazon. Read the directions on mixing before you do anything. The great part is that when you're done with the solution, you can dump it on your lawn and it won't damage anything. Getting rid of your caustic solution might be a problem. I used the same solution for several weeks to de-rust wheels, frame parts, castings, you name it before it got weak and I had to replace it.
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  5. Well,,,,,a few months ago I took my Flathead block and had it cleaned .
    It was baked ,,,,and the block is 70 years old .
    Everything was removed ,,,,old paint,,,,grease,,,,rust,,,,,everything .
    When I got it back,,,,,I washed it out and lubed it up good .
    The water that came out from inside the water jackets looked like blood,,,rusty tinted .
    This stuff flowed for several minutes,,,,I would think I was done,,,,then sprayed more water and more rusty blood would come out .
    The darkest looking water,,,, maybe it had some sediment in there as well ,,,,maybe some old stop leak,,,,,not sure .
    But,,, it was clean after that,,,I shone a flashlight back in there and can see the bottom of the water jacket all the way to the pan rail,,,,and the cylinders are clean back in there too .
    Any surface rust is baked away as well .
    They told me to be certain and lube it,,,because it will start rusting almost immediately with no protection,,,,,clean ,,bare iron will do that just from the humidity here .

    This was the first time I had a block baked clean,,,,but man,,,,it worked good !
    You might consider that,,,and save the extra cost of buying the acid ?
    Good luck .

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  6. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 2,344

    from illinois

    What would happen if the block was sprayed with phosphoric acid solution instead of oil/ grease .?
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  7. pirate
    Joined: Jun 29, 2006
    Posts: 460

    from Alabama

    It will turn a grayish/black color and that film will offer some protection against rust. I have done that with other steel or cast iron parts. When completely dry the grayish/black surface will serve as a primer for good paint adhesion. It’s a similar process to black oxide/Parkerizing that you find on socket head bolts and other steel products.
    Last edited: Mar 28, 2020
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  8. The best way is to flush all loose the crap you can first.
    Pull the plugs and and get up in there with a pretty stiff wire. Work it back in around the water jackets.

    We knocked shit loose that was too big to come out of the freeze plug holes. Had to fish it and then break it up not just scale but an astonishing amount of casting sand. The water ran solid Orange with chunks for at least an hour. Then it started clearing up till we got onto more deposits and ran orange again. Took Probably 3 hrs with a hose in every hole and wire poking in every hole. After all of that a dip would do something more effective.
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  9. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 2,344

    from illinois

    Just thinking it would afford cleaner storage / attract less dirt ??
    loudbang likes this.
    Joined: Mar 21, 2014
    Posts: 711

    from okc

    Hell man, I just shoved a water hose in the freeze plug holes and lotsa crap came out..... Good starting point, before the machine shop Hobart dishwasher
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  11. I've had good luck with citric acid solution for general rust removal. Haven't tried it on an engine block. If I did, I'd likely run some plastic tubing into a couple of openings, and run low pressure air to them to create a bubbler/agitator. Run it for a while, day or so, depending on concentration, and pull and rinse.
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  12. I strip the block and take my pressure washer after every hole. Works very well.

    Sent from my iPhone using The H.A.M.B. mobile app
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  13. Unique Rustorations
    Joined: Nov 15, 2018
    Posts: 340

    Unique Rustorations

    I started with a very rusty block that had probably been stored outside for years. I cleaned it first manually with the pressure washer then took it to the machine shop where they baked it, then ran it thou and blasting process finishing with a tumbler. Now I know that is not the specifics that you’re looking for (and it was expensive) but the block and the heads came back looking like they had just been cast yesterday. Here are a few pics. They don’t do it justice from where I started. Regards, Randy


    Sent from my iPhone using H.A.M.B.
  14. Looks really good Randy .
    It is amazing how good they look after the bake .
    Like you said,,,my old Flathead block looked new cast .

    Yours should make a really nice engine,,,,,looks very good !

    ekimneirbo likes this.
  15. We had a block done with Bake and Shake when putting together a friend's 40. I was impressed with the results, looked brand new, not just clean like a hot tank would do. But, now when we're staying at home, to suppress the spread of the Covid virus, it sure doesn't hurt to experiment with things we've wanted to try.
  16. lumpy 63
    Joined: Aug 2, 2010
    Posts: 1,138

    lumpy 63

    Just a word of caution regarding the bake , blast , tumble method... Pay extra attention to the lifter bores as this tends to very slightly peen the edges of the bores causing the lifters to stick and not spin in the bores . This will flatten a cam almost instantly. I always carefully scrape the edges of the bores and make sure every lifter spins freely. As far as home cleaning methods I have zero input:cool:
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  17. Unique Rustorations
    Joined: Nov 15, 2018
    Posts: 340

    Unique Rustorations


    Agreed. We honed my lifter bores. I’ll add that I wouldn’t do it to every engine as the cleaning and cleaning it again before assembly adds labor time. Every square inch and all of the oil feed holes have to be carefully cleaned multiple times. I went pretty far out on this one as it is going in my wife’s GTO and I’m sure it will be driven hard:)
    Regards, Randy

    Sent from my iPhone using H.A.M.B.
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  18. Joe H
    Joined: Feb 10, 2008
    Posts: 901

    Joe H

    This 455 was super rusty, I sand blasted it after stripping it down, then numerous power washings, and finally a wire brushing all before going to the shop for machine work and cleaning. It also got a final cleaning before assembly. With the plugs out of the sides, I was able to sand blast the inside of the block from each core plug opening and from the front. It looked like fresh iron after that.

    Attached Files:

  19. jimmy six
    Joined: Mar 21, 2006
    Posts: 6,333

    jimmy six

    Damn, Coronas are going away, what the hell are we going to do with all the limes? Glad I found Stella’s....they are only 11oz so I’m forcibly being able to cut back on my drinking..
    alanp561 likes this.

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