[GRX]

What would be the best way to de-rust my RA3 manifolds so I can paint them for my next build?

Molasses? Oxalic acid? E-tank?

[crm318]

Soak it in distilled white vinegar and water over night. The rust will turn black and flake off. A once over with a wire brush will take off the rest.

[GRX]

Was thinking vinegar too. My concern is rust, and chemicals in the remover, "bleeding" back out of the porous iron and through the hot paint.

[My442]

A shot trip to the blast cabinet and a short bath in WD-40 Rust Soak.

Don't paint them, have them coated.

[Bentwheelbob]

Media blast with coal slag or iron oxide and paint with POR15 manifold paint.

[HWYSTR455]

Exactly, media blast and coat with POR-15 manifold paint, or have them coated. Coating costs more, but will probably last longer. I've had real good luck with the manifold paint though and it lasts a long time. Can touch it up too.

Replace the studs, tap/chase the threads, and use anti-seize. Use anti-seize the entire length of the bolts and bolt heads when installing on the engine too. Tap/chase the head threads too.

EDIT: Eastwood high temp coating works well too. You can chemically remove the rust, but you have to etch it after, and before you paint. That ends up getting pretty close to the cost of blasting, so it makes sense to blast.

.

[GRX]

Thanks. Sounds like a trip through my local shop's steel shot blaster is in order.

[HWYSTR455]

If you use steel shot, it will make the surface smoother and won't look OE, if that concerns you or not. Will make it denser, which will help prevent cracking, I think.

.

[rohrt]

Harbor freight sells gallon jugs of Evaporust that stuff works slick. Doesn't leave a film after the metal is cleaned. I used to use phosphoric acid but like the Evaporust much better. If you don't have a blasting cabinet this is the way to go for small parts.

[PMD1969]

Electrolysis. I use a tall trash can and put the (pre-scrubbed) manifold in. Use tap water and fill over the top of the manifold and include a few tablespoons of Borax 20 Mule Team brand (Walmart), Using a 10 amp battery charger hook up the negative end to the manifold and the positive end to a three foot long piece of flat steel (1.5"x3') found at the hardware store. Put the charger on manual and let sit for 24 hours. If the piece has a ton of rust you'll need to change the water out at least once if not twice to get the majority of it off. Refill with new tap water and recharge for another 24 hours. I use Eastwood's Manifold Gray formula to coat them.

ETA: This process is messy but it does not remove material and it also gets the rust off from the inside of the manifold.

[Formulajones]

I use my blasting cabinet full of glass bead. They come out looking brandy new, almost a shame to cover it up with a coating.

I also agree about the Evaporust. Good stuff.

[craigs69]

I blasted mine with coal slag in a blasting cabinet and painted them with VHT Flameproof paint in the cast iron color (part #SP998). After 2 years, they look pretty much like they did when I painted them, with only very slight discoloration. The curing process is very important with VHT. If you follow the directions closely, the finish will last many years and is a lot less expensive than coating.

This is what VHT says on their website for curing the manifolds if they are off the vehicle. I did mine in the oven and could only get to 550 degrees, but it didn't seem to make a difference.

Paint must be completely dry before curing
Heat to 250°F (121°C) for 30 minutes
Cool for 30 minutes
Heat to 400°F (204°C) for 30 minutes
Cool for 30 minutes
Heat to 650°F (343°C ) for 30 minutes

Caution: Do not exceed the temperature of the least heat tolerant component or the base metal

[Greg Reid]

Originally Posted by craigs69

I blasted mine with coal slag in a blasting cabinet and painted them with VHT Flameproof paint in the cast iron color (part #SP998). After 2 years, they look pretty much like they did when I painted them, with only very slight discoloration. The curing process is very important with VHT. If you follow the directions closely, the finish will last many years and is a lot less expensive than coating.

This is what VHT says on their website for curing the manifolds if they are off the vehicle. I did mine in the oven and could only get to 550 degrees, but it didn't seem to make a difference.

Paint must be completely dry before curing
Heat to 250°F (121°C) for 30 minutes
Cool for 30 minutes
Heat to 400°F (204°C) for 30 minutes
Cool for 30 minutes
Heat to 650°F (343°C ) for 30 minutes

Caution: Do not exceed the temperature of the least heat tolerant component or the base metal

I used the same thing on mine and cured them the same way with an industrial oven where I was working at the time. They lasted and looked great for three or four years...until I took my car to the guy that painted it for me. The car sat outside for 10 months and when I got it back the manifolds were rusted. They remain that way today and I really don't want to remove them again at this point.
I've heard really good things about this stuff and I'll probably try it...
http://www.amazon.com/Calyx-Cast-Exh.../dp/B003D0R426

[77 TRASHCAN]

I had a pair of heads stripped, years ago. It's a reverse plating process. Took all the rust out of, off of them, looked like fresh cast iron when I got them back.
They advertised their business as metal stripping. Don't know of too many places that perform such services...

[GRX]

After some thinking an e-tank will be in my future. Lots of other pieces I can de-rust, and no worries about possible solvent residuals. Now to make some calls about used graphite EDM rods for the anodes.

[Formulajones]

Originally Posted by Greg Reid

I used the same thing on mine and cured them the same way with an industrial oven where I was working at the time. They lasted and looked great for three or four years...until I took my car to the guy that painted it for me. The car sat outside for 10 months and when I got it back the manifolds were rusted. They remain that way today and I really don't want to remove them again at this point.
I've heard really good things about this stuff and I'll probably try it...
http://www.amazon.com/Calyx-Cast-Exh.../dp/B003D0R426

Alot of that stuff in a can I've tried. Seems to be climate related. Living back East in the humid climate, that stuff might go a couple three years and then rust over. Out here in the desert South West these coatings last much longer and hold up fairly well with our 20% humidity and single digit dew points.

[craigs69]

Originally Posted by Greg Reid

I used the same thing on mine and cured them the same way with an industrial oven where I was working at the time. They lasted and looked great for three or four years...until I took my car to the guy that painted it for me. The car sat outside for 10 months and when I got it back the manifolds were rusted. They remain that way today and I really don't want to remove them again at this point.
I've heard really good things about this stuff and I'll probably try it...
http://www.amazon.com/Calyx-Cast-Exh.../dp/B003D0R426

I should add that my car is always stored indoors in a climate controlled garage and never driven in the rain.

[Formulajones]

Yep, mine were too. Only driven on sunny days and wouldn't come out in the spring until we had a few heavy rain showers to wash the salt off the roads. Yet even the $500 Jet Hot coatings I had on headers would only last 4-5 years before pitting started. Stuff out of the can might go 2 years tops.

It's those 90% humidity Cincinnati days with 70 degree dew points. The moisture in the air is so thick you may as well be driving in the rain, lol.

Out here in Arizona, don't have that problem. I'm not so sure I could even physically adjust to it myself if I had to go back.

[b-man]

Originally Posted by HWYSTR455

Exactly, media blast and coat with POR-15 manifold paint, or have them coated. Coating costs more, but will probably last longer. I've had real good luck with the manifold paint though and it lasts a long time. Can touch it up too.

Replace the studs, tap/chase the threads, and use anti-seize. Use anti-seize the entire length of the bolts and bolt heads when installing on the engine too. Tap/chase the head threads too.

EDIT: Eastwood high temp coating works well too. You can chemically remove the rust, but you have to etch it after, and before you paint. That ends up getting pretty close to the cost of blasting, so it makes sense to blast.

.

Here's how well POR-15 manifold paint held up after 5 years and 30,000 miles in Southern California on my RARE '67 GTO HO manifolds. They were new at the time I painted them but I bead blasted them first and used Metal-Prep on them before brushing on the POR-15 manifold grey.

[Bentwheelbob]

Originally Posted by b-man

Here's how well POR-15 manifold paint held up after 5 years and 30,000 miles in Southern California on my RARE '67 GTO HO manifolds. They were new at the time I painted them but I bead blasted them first and used Metal-Prep on them before brushing on the POR-15 manifold grey.

B-man - It was these pictures from an earlier thread posting that settled the debate for me on whether to use POR15 or Eastwood manifold paint. Thanks.