Painting aluminum engine parts

[chevynut]

I painted my iron BBC engine block with DPLF followed by PPG DBC base and PPG clear. I've read that automotive urethane is fine to use on engines so that's what I used.

However, I now need to paint my valve covers and intake manifolds which are aluminum. I don't think I can use the same process because aluminum requires different preparation and primers. They are clean, new, and have never been used on a running engine.

Has anyone here tried this, and what did you use? I did an internet search on the subject and some people recommend zinc chromate primer, some recommend etch primers, and there are a lot of other opinions. I want to topcoat with the same PPG base and clearcoat.

[chevynut]

Found this from PPG....they say to sand with 120-180 grit. Not going to do that. :(

http://us.ppgrefinish.com/PPG-Refinish/Training/Tech-Info/Articles-How-Tos/Aluminum-Prep

[oceangoer]

Painting Aluminium, my experience.

We painted the Mast of my Sailboat in 1993, it's nearly 60 long and has been in the Salty Ocean water Coastal environment since. No bubbles on paint issues. Just a few paint chips near the deck for years of hard parts whacking the mask. The finish Coat is still in very good condition after years of use in a tough environment, few waxing, and near constant rubbing or smacking of running rigging lines directly on the Paint.

Our Process,,,

sand blasted the Mast to bare metal,, blew off loose sand and dust Mast was set horizontally on steel waist high stands.

Acid washed the bare aluminum.

Acetone wash, poured Acetone over the mash while rubbing with while rags. Then a second pass only pouring Acetone on the Mast and let air dry.

Lightly sanded the mast to the manufacturers spec of the ZC primer, forget the grit size.

Acetone wash, same process

Applied Zinc Chromatic primer per exact manufacturers spec. We did not sand the ZC primer

Applied Feather Fill (Evercoat) a A two-part, polyester primer surfacer. Feather Fill can be applied o bare Aluminum, be I opted to use the ZC on the bare Aluminum. We lightly wet sanded surface.

Acetone Washed again

Applied While Delstar color, two prepared coats.


We let the mast set a few days outside in the Sun. All of the holes and treadled holes were cleaned and re-tapped threads prior to the painting process. After, all of the threaded holes we re-taped and a generous amount of Anti-Siege was applied.

Key points that I recommend are,,

Always wear latex gloves, Don't handle the bare aluminum parts with bare hands.

We wore good dust masks during the prep work, aluminum dust..

Once the Aluminum parts are cleaned with acetone, Immediately apply the ZC Primer, same for the FF Printer and Final Coats..

Once the ZC Primer has been applied, finish the project to the Color Coat as soon as possible.

Read your ZC and FF primer Tech Notes,, , As Not all Primers are recommended for Sand Blasted surfaces.

Good Painting ....

The Center Bolt Valve Cover on my C4 are a nice set of Bow Tie Aluminum (cast) Covers, But the Chrome has dulled over the years. I'm thinking that I might have the Chrome removed and paint these covers I'm concerned about the paint on hot valve cover.

Any recommendations or experience with a quality paint for valve covers ??

[chevynut]

Any recommendations or experience with a quality paint for valve covers ??

Are you wanting a standard color like Chevy orange or a custom car color? I figure valve covers don't get any hotter than around 225-250F, which isn't much hotter than coolant. Automotive urethane should work fine.

[oceangoer]

Prob Red or Orange, nothing exotic.. Car's is a Red Convert , most likely Red...

It's a Fast Burn ZZ4 with the typical center bolt covers. The Chrome valve Covers look awful now, time for some engine by clean up.

thanks,

Michael....

[55 Rescue Dog]

Unless it is trashed, I think bare clean cast/machined aluminum looks awesome. Plus, no paint or polishing required.

[chevynut]

The only problem with bare aluminum is it's all silver unless it's anodized a different color. ;)

My engine parts will be painted dark gray to match the engine block and the rest of the drivetrain. T56 tranny will also be painted dark gray. Polished and chromed stuff seems to be going by the wayside, and I don't want to be polishing aluminum all the time which it needs or it gets ugly.

[55 Rescue Dog]

That's why silver looks so good on steel, or aluminum, and even car bodies. It's the natural color.

[NickP]

I think bare clean cast/machined aluminum looks awesome. Cast AL gets too dirty

[55 Rescue Dog]

Cast AL gets too dirty
Only if it gets dirty, then you just clean it like anything else. Unless you have leaks, or salt.

[chevynut]

The fact is aluminum oxidizes, and it gets dull pretty fast. I brightened up my 502 heads with some aluminum cleaner but manifolds start looking crappy in a couple of years imo. Paint is easy to take care of.

[Rick_L]

Besides the oxidation, cast parts are not smooth get really hard to clean after they get dirty.