Register now to get rid of these ads!

How is the best way to clean up a old rusty engine block?

Discussion in 'The Hokey Ass Message Board' started by willys_truck, Nov 21, 2005.

  1. willys_truck
    Joined: Mar 4, 2005
    Posts: 769


    I have a small journal std bore 327 block that I am needing to clean up to build my 301. The block sat outside for a couple of years and has heavy surface rust all over it. Would it be best to sandblast it? get it dipped (the same stuff that bodies get dipped into)? electolysis it? or? does anyone have any suggestions? I am needing to get it cleaned up ASAP, so I can get it bored and built up for my gasser. Any does or don't posts would be great. I am kind of lost on this. THANKS
  2. FEDER
    Joined: Jan 5, 2003
    Posts: 1,269


    I got a REAL rusty marine 440 block, took it to a local machine shop and they shotblasted it in a cabinet. It uses steel shot. The block came out really looking brand new. It does rough up the bore but needed boring anyway.The cam line was fine but did hone the mainline. Feder
  3. zman
    Joined: Apr 2, 2001
    Posts: 16,510

    from Garner, NC

    I'm a big fan of the hot tank, most machine shops will do it for around $30, or at least they will here...
  4. noboD
    Joined: Jan 29, 2004
    Posts: 6,210


    Do a search here on molassas. It works! Cheap, takes about a week.
    Register now to get rid of these ads!

  5. Take it to a machine shop and have them drop it in a hot tank,,most engine builder in this neck of the woods VAT the block and they clean up very well. HRP
  6. fab32
    Joined: May 14, 2002
    Posts: 13,989

    Member Emeritus

    All hot tanks that I'm aware of will not remove rust. They are fine for oil, sludge, grease and paint but when they are done the rust still remains.

    The best block cleaning system is where the block is baked at temperature that reduces all petroleum products to white ash followed by a trip in a shot blast cabinet. This last procedure is where the block is mounted on a rotating fixture inside the cabinet all the while being blasted from multiple angles to insure no surface goes unexposed to the blast. When the block emerges from these two procedures it will be as clean as a new casting and look like one.

  7. willys_truck
    Joined: Mar 4, 2005
    Posts: 769


    I talked to the only 2 local machine shops around here and they said there vats would not touch the rust, just clean grease and sludge, maybe I need to talk to a couple of different machine shops! I thought that was what the vats were for rust,grease grime, or whatever?? I do not have ANY machine shops here in my area that I TRUST to do anything to my engines or anything else for that matter. That is why I do all my work myself, but this has me stumped. I know I could blast it and clean it up, but sandblasting leaves a rough surface and I do not like the thought of having a rough surface in my lifter holes where my $400 dollar roller lifters are going to to be!
  8. The best way I've found to clean blocks, heads, cranks, etc.. is in a thermal cleaning system (AMPRO is one brand name). The way it works is, the block gets mounted in a cradle and put in an oven. The cradle rolls while it "cooks" it. When it comes out of the oven, it's all black and nasty. The next stage is the shot cabinet. The cradle gets put in the cabinet and rolls while 2 big paddle wheels in the bottom of the cabinet sling shot at it. It's actually short pieces of wire, but after it's run for a while it looks like shot. Once it's done in the shot cabinet, it goes into another cabinet where it rolls and rocks side to side, all at once. Meanwhile a large vacuum sucks up all the crap. Not every shop will have the 3rd stage of the process, but it works great for getting all the debris out of the water jackets and oil galleries. Once you pull the block out of the last cabinet, it looks like a brand new casting- no shit!Now, there are some things to keep in mind if you get your engine parts thermal cleaned. When you prep the block/ head, you'll need to remove EVERY oil gallery plug, frost plug, cam bearings... everything. Once you get it back, you'll want to a) get a coat of something on it (if the machine shop didn't already) because the thermal cleaning opens up the pores in that cast iron and it'll rust almost instantly, and b) you'll need to carefully run a tap through every bolt hole in the part. The reason being that, the shot in the second stage will sometimes roll the first thread on your bolt holes, and it's a good way to ensure that all the shot and debris are gone.
    I think that it's the only way to go. As a machinist, I don't think it's possible to get parts too clean.

  9. And I almost forgot, you'll need to chamfer the lifter bores.

  10. willys_truck
    Joined: Mar 4, 2005
    Posts: 769


    That sounds like the way to go wrenchbender, now I just need to find a shop around here that actually has the equipment to do that. when you say cham the lifter bores do you mean hone them? THANKS
  11. A small wheel cylinder hone or a dingle-berry hone would work to put a nice cross hatch back in the bores, but the shot has a tendancy to roll a slight lip on the lifter bores. I use a chamfering tool. It's sort of cone shaped with vertical blades on it. Otherwise, a normal machinist roto-bur might work. The most important thing is that the lifters move smoothly in the bores.

  12. As an experiment I dropped an ugly rusted '36 gear case into a mollasses tub to try a "worst case" scenario. After a couple of weeks, I was amazed at the result. Not in the same category as cylinder and lifter bores, but an incredible turnaround just the same. Cheap and effective, enviro friendly but kills anything other than iron/steel (eg. cam bearings). Parts have to be paint/grease free.

    When you rinse off the mollasses goo, treat the raw metal straight away - it gets surface rust back real fast.
  13. 51 pickem up
    Joined: Apr 7, 2005
    Posts: 205

    51 pickem up
    from mosheim,tn

    ifin you got a small tub soak it in white vinagar for about 4 or five days.
    it will cone out like new after you clean it.
    al sisson
  14. Don't sandblast it. You don't need to do anything. Take it for boring and cam bearings to a professional shop that does that kind of work. Before they do the machine work they'll hot tank it, spanking clean. Ask them to check all of the mating surfaces, intake, head, pan, front cover. If there are any dings, they need to be smoothed/level. Any irregularities on the intake or head mating surface may need milled. The mains need to be checked for alignment and bearing fit. You can have the shop do that or if you aren't familiar, have someone that is help you do that when you install the crank. After you get it back you should check the oil gallerys and make sure the holes line up on the cam bearings. There will be microscopic metal residue in the oil film it has on it from the machining. Leave it alone until you are ready to build the motor. At that time wash it good with hot soapy water, scrubbing it with a brush (remove all of the machining oil residue) and blowing out all the cavaties with compressed air. Then you need to dry it good. Mask off all of the mating surfaces and inside, and paint the outside. After the paint is dry coat all of the unpainted surfaces completely inside and out with motor oil to keep it from rusting. Then cover it with a lint free blanket, (don't want them lintballs clogging the oil galleys).

  15. Please don't get me wrong, I'm not attacking your machine shops, but a REPUTIBLE machine shop that does dependable reboring will hottank, removing the rust. Don't forget that motor rebuilding shops do outside work, and sometimes for less than a small town machine shop. If they overhaul, they hottank.........

  16. krooser
    Joined: Jul 25, 2004
    Posts: 4,586


    Fab32 is right....One of my Hemi blocks that I'm building right now sat outside for ten years...we had to bust 6 of the pistons out of it. Two were seized so tight the machine shop used a 40 ton press to get 'em out...they baked and shot blasted the thing and it looks like new...better, even.
  17. Or----If you are a cheap guy like me, spray it with oven cleaner, wrap it in plastic sheeting overnight so the oven cleaner doesn't evaporate away. and hose the hell out of it next day with the hottest water available to you. That gets rid of 95% of old grease buildup. Then put on your safety glasses, get out the right angle grinder with a 3" or 4" wire cup brush on it, and wire brush the living hell out of it. This will not give a bare metal finish like bead or sand blasting, but it won't leave the engine cavities full of abrasive particles either.
    This method is cheap, effective, and doesn't mean transporting the engine around.
  18. ironpile
    Joined: Jul 3, 2005
    Posts: 915


    I`ve experimented with electrolisis,takes off rust and grease and paint if rust is under it. Very inexpensive,easy. I don`t like to blast engine blocks due to trapped media,invariably gets into the oil system. If your interested I`ll try to link you up. Jerry:D
  19. 286merc
    Joined: Mar 3, 2001
    Posts: 1,794

    from Pelham, NH

    The only useful remaining commercial system is the baking as mentioned. The hot tanks that remove rust are just about all out of business thanks to the EPA since they use a highly dangerous hot alkaline (sodium hydroxide)solution. It is NOT the same hot dip that simply removes grease & paint.

    I have my blocks dipped (cam bearings removed) to get rid of the grease and paint. Then bring home for the molasses dip which gets every bit of the block and water passages looking like new. Electrolysis is useless for anything hidden from the electrodes so it wont do squat in water jackets much past the surface.

    To protect the block from flash rust you can either lightly oil it or give it a spray of 2% solution of PrepStep and water. PrepStep is good up to about 6 months (redo it for another 6 months) and can be painted right over
  20. Is there a RediStrip franchise anywhere around you? That is about the same thing 286Merc just mentioned: a hot alkiline treatment. It worked like a charm several years ago on my flathead-I just wish I had known at the time that there is a rear main seal retainer hidden up in the block. It ain't iron and it disappeared in the tank.

Share This Page

Register now to get rid of these ads!


Copyright © 1995-2013 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.