Matt Harwood

Cleaning oxidized aluminum engine parts

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I have a Ford flathead with aluminum heads and intake manifold, and they're a little crusty with oxidation. I don't want to disassemble the engine to remove them, but I'd like to clean them up a bit. Does anyone have a solution or chemical they use to clean it up? I was thinking something like CLR maybe, but I've heard vinegar works, too. We're scrubbing with a Sotch-brite pad, which helps a bit, but I was thinking that combining that with some chemical action would really brighten up the aluminum parts.

 

Anyone done this before and have some advice? Thanks!

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Benefits of AACA Membership.

Matt,

I use "Semichrome" polish.

It is pink in color and comes in a tube, like toothpaste, and I get it from my local motorcycle shop.

You can probably get it online though.

This stuff is the BEST for aluminum, and it also does a fine job on stainless.

 

Please don't use anything stronger than lubricated "Scotchbright" on aluminum.

 

Mike in Colorado

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I should note that this is raw as-cast aluminum, it has never been polished. Would an actual polish clean it up? It mostly looks grungy where oil and gas have leaked on it and soaked into the pores of the casting, plus the oxidation on top. I don't want a shine, I just want it to have a nice, clean look. Would those polishes work on raw castings or are they for already smooth surfaces?

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Look for mag wheel and aluminum cleaaners .  I have used this along with a wire brush.  It takes some elbow grease but it makes aluminum look brand new.  An actual polish or even scotch brite would probably not reach into the cracks and crevasses of the cast aluminum.  Good luck!

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Try spraying it down with WD-40.  It will remove the crud and leave a protecting coat on it.

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Matt,  Glass bead blasting leaves a very pleasing satin finish on cast aluminum parts.  Keep this in mind if you ever have the parts off, or want to be adventurous and try masking and blasting.

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 "alum brightener"  Made just for this application. Available at truck stops and truck parts stores everywhere.

 

You will have to first wash off all grease and oil before using.

 

​ Caution, will turn gavanized parts black. If this happens, re-apply, scrub with a brush and rinse quickly.

Edited by Roger Walling (see edit history)

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I use mag wheel cleaner on BMW motorcycle cases to great effect with gray Scotch Bright . Repeated use will remove the cadmium plating though. Degrease first ,of course.

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First, when it comes to glass bead blasting, you need to be clear on the media.  There are glass beads (little round glass balls) and then glass grit (small broken glass pieces) which is sometimes improperly referred to as glass bead media.  Make sure you know what you are getting.  Also, true glass bead media will shatter and turn into grit if used at too high a pressure so you need to keep the pressure down a bit...I suggest 80 psi maximum.

 

If you blast aluminum with sand or glass grit you will get a very flat finish which will pick up every bit of dirt when touched, so beads are the way to go.  The problem with beads though is they will not get into all the tiny crevices and clean the way a gritty media will unless you select a very small bead size which doesn't give you quite the same sheen as a little larger bead diameter.  I used a process a bit different than Dave's above and, again, this only works if you remove the parts.

 

I sandblasted my aluminum pieces.  Then, instead of glass beads, I blasted with steel shot (steel beads) which you can run at a bit higher pressure without worrying about shattering the beads. This process gave a really nice and very clean satin finish. I opted to clearcoat with Eastwood's Diamond Clear - Satin. Another option would be to use two different glass bead sizes, one for better cleaning and the other to get the sheen you want.

 

If you are doing heads, I would not recommend sand/grit blasting in the combustion chamber as little pieces get imbedded in the material that cannot be removed.  Same goes with pistons, rods, etc.  Beads are the way to go for any internal engine components.

 

Just sharing my own experience.

Scott

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Curious?

Wouldn't steel beads (shot) permeate into the aluminum making it vulnerable to rust?

I am thinking that a good messy pressure washing might be all it needs. That could be done in car.

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I would think the best and easiest with the stuff still on the engine would be a pressure wash using a mild detergent like Dawn dishwashing liquid, then rinse with clear water.

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Aluminium is at the top of the galvanic series with zinc. Zinc-alume is used as an "anticorrosive" treatment (i.e. a sacrificial anode) on steel.

 

The corrosion oxides are white and powdery. If you want it to not corrode again, it should be fairly smooth. Once an oxide film forms, corrosion slows. It is very difficult to coat it soon enough to prevent further oxidation once you off the oxide coating, e.g. with blasting. I imagine the casting is fairly porous on the surface so readily absorbs a certain amount of fluids like oil. Bead blasting should reduce that surface porosity. A detergent would be a better bet than a solvent to remove the oily residues - solvents will just spread them further.

 

Because of its susceptibility to chemical reaction (= corrosion), be very careful of acid and other products that work with acid (such as vinegar = acetic acid). If you do use any acid, neutralise it afterwards with sodium bicarbonate (pH buffer from a pool shop for example).

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Thanks for the advice, guys. I'll hit NAPA in the morning and pick up some Aluma Bright and see how it works, probably in conjunction with a Scotch-Brite pad. Just enough to make the aluminum castings silver again, not polished or shiny, just clean.

 

Will post some photos of the results. Thanks!

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Jack M, that is possible, if you use a regular steel brush on stainless, for example, the regular steel ground into the stainless will rust on the stainless......

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Agree with Spinneyhill, but for sodium bicarbonate type neutralizer, just dissolve baking soda in water.

 

(the fine polishing abrasive is "Simichrome", used in the tooling industry for many years)

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Thank you trimacar.

I like to learn something new once in awhile.

 

So is steel wool not the right thing for polishing stainless?

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I use Mothers Aluminum. Cream and I am very. Impressed! Now available in the chain stores, very easonable ! Wayne

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Matt, my suggestion for cleaning aluminum that is soiled from petroleum distillates is conventional brake cleaner. Just a terry towel for quick cleanup around the painted edges.

Once that is cleaned up and dry, use a product from the aircraft industry  ACF50 on the discolored blotches of the aluminum surface.

  I have used this successfully on the aluminum blower tops and heads of supercharged Auburns, after unfriendly winter storage. 

If you have questions PM me , we can talk

Edited by Curti (see edit history)

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I have several cast aluminum cage light fixtures - what you would regularly see on docks, marina, yacht clubs, etc., around the waterfront. They have a red and green light used as "navigation". To replace the bulbs one simply unscrews the top cage part from the bottom base that has the light fixture inside. As you all mentioned above, the raw aluminum oxidizes with a white powdery flake just with exposure to the elements. We have not been able to unscrew the two parts with sheer force of twisting and don't want to crack them, so are wondering what liquid substance we can soak the fittings to perhaps "unstick" the "rust" so it will unscrew. I have read about vinegar, wd-40, etc., but still just not sure what substance you all recommend to eat away at the corrosion, like what hydrogen peroxide does on plant based substances, for example. What works??!! Thanks for your recommendations to Huntley@RhapsodyDesign.com.  ALSO!!! I just remembered that I also need a source for ball joints for my 1964 Convertible Bonneville - any ideas on that too?? Thanks guys and gals, H :)

1964 Bonneville Pontiac Convertible on Intercoastal Waterway, SSI, GA.JPG

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For thought jobs try any aluminum may cleaned rub a bit on and a squirt of wd40  . Lots of rags and elbow grease won't hurt 

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On 9/24/2015 at 9:30 AM, Dave Henderson said:

Matt,  Glass bead blasting leaves a very pleasing satin finish on cast aluminum parts.  Keep this in mind if you ever have the parts off, or want to be adventurous and try masking and blasting.

 

I use plastic media on aluminum and not glass beads.

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We glass bead aluminum parts which was probably how they were treated at the factory to remove all the casting sand and core material.   Either that or they were sand blasted.

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