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Discussion Starter #1
I worked on my engine mounts today, and I found that the aluminum pieces were painted inside and out. I have found this silver paint on all of the engine aluminum bits I have worked on so far. Before today I thought that this may have been done to my car in later years to pretty up the engine, but now I think that this is how it left the factory.

I have a 61 2000. I am not sure if I am going to repaint the aluminum.

Doug
 

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As an owner of a very original, unrestored 60 Spider, I'd have to say that your observations are not in line with what I see on my car.

Just sayin...
 

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Discussion Starter #3
Hi Dan,

What year is your car - Maybe this was not done on earlier years. I could very well be wrong but I find it fishy that the inner part of the engine mounts were painted.

Doug
 

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Hi Doug - Mine is a 1960 and doesn't seem to have any paint on the aluminum engine components.

Richard
 

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Doug,

In general, I think any aluminum item that is painted on the inside would indicate an aftermarket repair. It is considered to be poor engineering practice to paint any surface that is going to be bolted/mated to another surface, as the paint can compress with time causing the fasteners to lose their tension and fail. I realize that a very thin coat of paint is unlikely to do this, but factories tend to follow a "best practices" approach to such things, and mating painted surfaces is not a best practice.

More likely the engine was overhauled and the mechanic just hung the mounts from a wire and sprayed them all over rather than masking the mating surfaces. I routinely piss off my powder coating guy by insisting that all gasketed/mating surfaces get masked. He charges me punitively for the work.
 

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Hi All,

All alu engine parts were original not painted

only the outside of cilinderhead and cam covers were painted in black wrinkle finish

rgds Franco
 

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Doug...

As a thought...

High quality aluminum castings will often have a very light coat of pure aluminum plated onto them. This is because the castings may be made out of one of several alloys that increase the strength, but result in the aluminum being more prone to various corrosion issues. After the casting is completed and machined, the manufacturer will have this very thin coat deposited onto the casting, as pure aluminum is more resistant to corrosion than many of the higher strength alloys. I don't know if Alfa did this, or what alloys they may have used for their castings. When bead blasting this type of casting the shiny pure aluminum coating can be seen to wear away, appearing somewhat like a thin paint. This issue is known in aviation, and we take some care to leave the pure aluminum intact. Failing that, we'll puff on a very thin layer of zinc chromate, as this helps to protect the alloy underneath. A VERY thin coat, such that the aluminum is still somewhat visible. Thin enough that any paint-compression issues are avoided when bolted into an assembly of some sort.

Note that "sand" blasting should never been done to aluminum, or even steel for that matter. It severely erodes the metals, and depending upon the source of the sand, will deposit salt and other nasties into the surface of the metal. Bad news.
 

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Discussion Starter #9
Thanks for the information. I am not sand blasting at all. I use wire brushes and razor blades mostly. It takes a long time to clean a part - especially with all of the impressions from the sand during casting!

Doug
 

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You should never use a metallic wire brush to clean aluminum. It will impregnate the surface with the metal from the brush, leading to future corrosion or worse. Scotchbrite is ok. Plus, the steel brushes abraded the aluminum badly. Wire brushes are for cleaning iron and steel parts.
 
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