Help on restoration of Aluminum engine pieces

Tony.dreamer

Tony.dreamer

Raider of the lost parts
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folks,
In process of the resurrection of my 71 CS 2800 there are so many pieces like valve cover , oil pan , mounting plates for AC, etc that are made of Aluminum color alloy of some form. What is the best way to make them look new again? Should I have them plated ? Which method is the best? I know some friends have used some silver engine paint topped with clear coat. But he doesn't know how long it last...
I am also going to use a m30b34 engine (most likely) and I have a running donnor 1981 528i which I will be using the Ram intake manifold as well as other items ....
So there will be plenty of the shinny Aluminum colored engine pieces...
 
What i did is when the pieces were off for new head gasket i had them bead blasted. Then all I do now is use some marine polish every so often to keep it looking nice. No paints or clears to wear off etc and it has a nice clean natural look.
 
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My intake and some of the other visual aluminium parts were sand blasted and after that I put a clear coat of powder coating, IMO it looks very nice and easy to keep clean.

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I wanted the closest look to OEM and ease of maintenance so I had those parts tumbled and then clear ceramic coated. After tumbling the oil pan I had it ultrasonically cleaned to remove debris from under the baffles.
 
HB Chris said:
I wanted the closest look to OEM and ease of maintenance so I had those parts tumbled and then clear ceramic coated. After tumbling the oil pan I had it ultrasonically cleaned to remove debris from under the baffles.
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engine5.jpg

And the result is very nice and lasts a long time with wiping down being the only maintenance.

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HB Chris said:
I wanted the closest look to OEM and ease of maintenance so I had those parts tumbled and then clear ceramic coated. After tumbling the oil pan I had it ultrasonically cleaned to remove debris from under the baffles.
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What types of shop can do ultrasonic cleaning for engine parts? I have taken my wife's jewelry once or twice to the jewelry shop for that but that's the extend of it.
 
Sandblasting aluminium leaves the surface quite open pored. A coating is needed to be able to keep it looking nice. But when it flakes after a few years, it get dirty easily and is difficult to clean as the dirt digs into the pores.

Tumbling the parts with stainless steel needles, balls of UFO shaped things pounds the surface clean, but also creates a closed surface; much easier to clean. Can be coated, but not needed anymore.

For a top notch restoration tumbing is the way to go, also for carb parts.
For both methods, take care to cover holes with acurate dimensions, threads etc. Foam ear plugs work well for that.
 
eriknetherlands said:
Sandblasting aluminium leaves the surface quite open pored. A coating is needed to be able to keep it looking nice. But when it flakes after a few years, it get dirty easily and is difficult to clean as the dirt digs into the pores. Tumbling the parts with stainless steel needles, balls of UFO shaped things pounds the surface clean, but also creates a closed surface; much easier to clean. Can be coated, but not needed anymore. For a top notch restoration tumbing is the way to go, also for carb parts. For both methods, take care to cover holes with acurate dimensions, threads etc. Foam ear plugs work well for that.
Click to expand...
Clear anodize (Type II) or even clear "Alodine" (a chem finish) will seal clean cast, blasted, or machined alloy surfaces. Unless the surface is then subjected to decades of salt-water blasting, the surface finish is permanent and will not flake off like paint.
 
I have Alodyne coated a few parts after bead blasting and the finish looks very nice. This is the process done in aircraft restoration for the most part.
First you treat them with alumiprep chromium conversion, then soak in Alodyne bath for twenty minutes. Quite easy to do and no awful fumes.
The products I used were made by Henkels. The finished product is fairly low key.
 
Anodizing cast aluminium parts can give "surprising" effects. Casting grades of aluminium usually have a high lead content, which gives the aluminium a dull grey to dull dark grey colour after anodising. Although they will be technically durable surfaces, it may not be what you expect visually. Yellow shades appear when there is a higher copper content.

Without knowing the chemical composition of the aluminium at hand, there is no certainty what shades may appear out of the bath.
For critical components, you may want to try it out.

If you are re-anodising parts, or if someone else tried it before with same partnumbers and is happy, you should be OK.

Erik.
 
eriknetherlands said:
Anodizing cast aluminium parts can give "surprising" effects. Casting grades of aluminium usually have a high lead content, which gives the aluminium a dull grey to dull dark grey colour after anodising. Although they will be technically durable surfaces, it may not be what you expect visually. Yellow shades appear when there is a higher copper content.

Without knowing the chemical composition of the aluminium at hand, there is no certainty what shades may appear out of the bath.
For critical components, you may want to try it out.

If you are re-anodising parts, or if someone else tried it before with same partnumbers and is happy, you should be OK.

Erik.
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Thanks Erik for clarifying the process for me. I knew a little bit and I did anodize some aluminum pieces in an old MG . With your explanation i am more informed about what options I really have.
 
This is a great topic. My experience is mainly with aluminum parts on my XK120, which see GOBS of oil and grease contamination (it's an old British car, leaks are by design). The parts that were painted with a catalyzed silver paint still clean up like new 6 years later. The only unknown for me is how well this finish stands up to fuel stains (SU's don't dribble and leak like Weber's and Zeniths).

I agree with the other posts that ballistic with most abrasives makes aluminum parts harder to keep clean. Maybe true glass bead (not crushed glass), and walnut shells at appropriate pressures would be less of a problem.

Anyway, I intend to either ceramic clear coat (same thing that Speedway does for HBchris and Stan) or keep using silver paint on the lower on the sump, brackets, etc). Both create a durable sealed surface that wipes clean with a spritz of winded or detailer.

John
 
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eriknetherlands said:
Anodizing cast aluminium parts can give "surprising" effects. Casting grades of aluminium usually have a high lead content, which gives the aluminium a dull grey to dull dark grey colour after anodising. Although they will be technically durable surfaces, it may not be what you expect visually. Yellow shades appear when there is a higher copper content. Without knowing the chemical composition of the aluminium at hand, there is no certainty what shades may appear out of the bath. For critical components, you may want to try it out. If you are re-anodising parts, or if someone else tried it before with same partnumbers and is happy, you should be OK. Erik.
Click to expand...

Well of course, different alloys will look different when chem finished or anodized.
Very unlikely you'll find copper added to the alloy mix for cast automobile parts due to a) cost and b) corrosion.

Wonder why most folks over the years just used a silver powder coat?
Some day I might check to see if there is a hammerite powder coat, THAT'd look cool, though may be a somewhat inconsistent finish ;-)
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