Bfenty

Title says it all. Wondering if I can sand blast my valve covers or if that's a bad idea. Never sand blasted anything before. I used paint stripper on them and they're a lot better but still need a little work and I'd rather not sand by hand if I can avoid it. Eventually going to repaint them high temp silver. They're the original magnesium covers.




Being stripped



After strip. Hard to see but still paint in the cracks and on the ends a bit.

johno504

bead or walnut shell blast 'em........ not sand

unclet1

I agree, Something other than sand. I use bicarbonate of soda (baking Soda) to remove paint from my painted parts. If you were closer I'd blast them for you.

confab

I carefully sandblasted mine. Turned out fine.

Stay back off of them. Don't stay in one place too long. They're fairly soft.

dmaxx3500

yes you can,just wash them real good afterwards,,ive done 10+ sets

DMITTZ

probably better to 'media' blast them, just wash and blow them out really well afterwards.

I media blasted mine with fine crushed glass then power coated them and they came out really nice.

confab

PS: The casting quality on the early ones (at least) is TERRIBLE.

Expect to spend a little time with a file and sanding to get them to look decent. The thick factory paint hides a bunch!

HAD2HAV2

I have a simple sand blast gun. It only uses play ground sand. This type of blasting should be fine. Your next decision after blasting will be to clear or paint your valve covers. This type of spray gun is cheap but you need an air compressor.

Bfenty

Thanks for all the replies! I decided to sand them down the old-fashioned way, by hand. They turned out pretty well but there were a few imperfections that showed up when I painted that didn't before. Annoying because of all the work I put in, but not so bad I want to strip them down again.

Now the question is, do I need to use high-temp clear coat on them? I've seen conflicting opinions elsewhere, so I'm curious if anyone has used normal dupli-color clear on their valve covers, and if they have any issues. I'd just go buy the high temp, but I've got like 4 cans of regular clear I'm trying to use up.

jts90vette

Your work looks great. I wouldn't use clear, it might turn yellow over time. Just my opinion.

confab

frankinvett84

Did anyone else get "bubbles" between the fins on top .Why does this happen
. also could I use Bondo or something similar to cover casting defects? Yours did come out NICE! Sorry to high jack but I did mine a while ago and now the bubbles are getting worse..

DMITTZ

If you got bubbles in the paint and now they are getting worse, it is likely a paint adhesion problem. My guess is the surface was not perfectly clean before you painted it. They way to prevent that is to make sure the surface is perfectly clean before you paint and if you are using a paint that requires mixing be sure to follow the fixing directions closely.

If the bubbles are in fact bumps in the actual metal from casting defects then you can grind/sand them smooth before painting or maybe use filler but I'm not sure how well body filler does in a high-heat application like and engine.

1800Wing

Bubbles or lumps are almost always the result of contamination. When painting items like this if I bead blast them I always follow up with a drill powered soft wire brush.

After each step I wash them in soapy water with some simple green ( use the simple green sparingly )

Just before I shoot them I always wipe down the surface with a good quality lacquer thinner, of course I shoot a primer coat. Easier to remove crap from the primer than expensive epoxy.

Quality paint work ALWAYS requires meticulous surface preparation.

Here's a couple of pictures of what time in preparation will give you.

Before ( with millscale removed ) and after.

Bfenty

Wow those are good results! Yea I wish I had bead blasted mine. I just hand sanded, thought I had a pretty good surface, but the metal was a bit pitted I think. I did wash them pretty well with simple green then wiped down with isopropyl alcohol.

Bfenty

One thing I did that I don't think I mentioned in the original post is I baked them in my BBQ on low for about 30 minutes and then cleaned them again. Vikingtrader recommended this step to me because the metal is porous and can get oil in it that bubbles out at heat. Mine did "bleed" a little oil this way, perhaps that's what is happening to you?

Dt86

http://www.powdercoatguide.com/2014/...l#.WSMfBlQpCf0

Step 4.

Bfenty

outgassing is important

confab

With used parts, it REALLY DOES help before powder coating. I have an electric oven here dedicated to powder coat, and the pre-coating heat up evaporates a lot of oil and nastiness that hides in the crevices.

The smoke on the pre-heat compared to subsequent bake makes it completely obvious you're removing hidden oil and grease.

Joe C

well, since I assumed the subject was PAINTING valve covers, and not powder coating, and while an outgassing step might apply to powder coat, baking parts in a dirty, old, greasy, outdoor BBQ grill, prior to painting is utter BS. personally, I could care less what anyone does, but FWIW, I've been refinishing (paint) various types of castings for well over 40 years, and have yet to throw anything on the Weber outdoor. as a mater of fact, I've probably refinished a dozen sets of corvette magnesium covers over the last 20 years without a "cookout." I guess while you're at it, you guys could save some time, and throw on a couple burgers.