jeff spahn

So what will happen to my intake if I don't sandblast the intake and covers and paint over the black finish. My friends company that does soda blasting said it would take something like 8 bags of soda and 20 hours to get the black corrosion off the parts. 1 bag of soda did about 4 square inches.

His machine is the real deal. he's pushing 120 cfm through it to do the blasting.

So. Do I blast with sugar sand and then become Mr. **** and clean the crap out of it or do I epoxy paint it over the black finish?

Looking for opinions. This is the last step before I re assemble the car. Have about a month before I have to get the car out of that slot in the garage so I can start raising our laying hens for spring.

Speedtoys

That oxidized layer will shift off anything you put on it.

Is it that hard to find a place that can blast aluminum properly in the quad cities?

Mrmerlin

IIRC the intake is magnesium, the dark color should not be an issue if its degreased and then baked

jleidel

Wow. 20 hours is pretty extreme. We sandblasted an S4 intake and end covers this weekend using a Harbor Freight outdoor handheld gun and glass bead. It required less than half the bag [50lb bag] and ~1 hour. [granted, i had treated it once with a chemical stripper].

Ed Scherer

FWIW, the guys that did my prep and powder coating used aluminum oxide blast media. IIRC, they said it took a few hours (can't remember exactly how long, but it was less than a work day). This was for both inside and outside surfaces on intake, intake end plates, cam covers, water bridge, and thermostat neck.

Rob Edwards

Soda isn't aggressive enough even at 120 psi. Needs aluminum oxide or a glass bead/Al oxide mixture.


That said, the plating company here had to send mine out to have it dipped first, then they media blasted it.

Get it so it looks like this on the outside:

blandis

I was leary of blasting at all. Dont want anything sucked down in the cylinders.

Used a couple cans of chemical stripper from lowes. I used putty knife and picks to flake off any loose material. I think this is the correct product below. There are several, one of them is safe for alum.

http://www.lowes.com/pd_211758-34228...pper%2Baerosol

The overspray is wicked....get some good gloves. If the wind is blowing watch your neck and face! I also did the inside of the intake as well. I coated my valve covers and intake good, put them in bags loaded them in the back of the jeep and took them to the carwash by the time i got there paint was pretty much loose.

I washed the crap out of them. Coated it one more time after the first powerwash and let it set like 15 minutes and that did it. Take few dry towels with you to carwash to dry off with. I was soaked to my boxers! Stuff flys everywhere with that wand and getting down in the nooks and crannies.

I got probably 95% of the coating off my intake and valve covers. Prime them good. Then I used a wheel paint on mine. So far so good, but only been about 6 months.

jeff spahn

Well, all the paint is already off from the walnut shells. Just need to decide if I should take off the grey layer down to silver or MEK the parts and bake it off in the oven for a couple hours then paint it

BPG_Austin

Hey Jeff. Aluminum Oxide and glass bead will both cut through the gray coating and take you down to bare Magnesium. I'm really suprised you were able to strip your parts with walnut shells. I have some at my shop that shoot around the cabinet like popcorn kernels when I try to use them on the intake. The pics I attached are of freshly blasted parts. They were chemically stripped and then blasted as Robs. I haven't found any other method that does the job. If you're going to paint you're probably fine with what you have. Just make sure the parts are thoroughly degreased for good adhesion. I'd bake them if you have an oven just to be sure. Or, just give them a good scrub with some dishsoap and dry with a fan. If they're to be PC'd they need to be completely clean.

Speedtoys

Pure Mg? Or an alloy?

bwoyat

I had my cam covers and intake walnut blasted for about $150 and it turned out great. Poweder coated it a couple years ago and it still looks like new.

Jim M.

Intake and cam covers on an S4 and up are an aluminum/magnesium alloy. Once you get the paint off the alloy will oxidize very quickly (just hours) so if you go down to bare alloy you need to prime and paint or PC right away. You also need to bake them to get all the oil out of the alloy or no finish will last very long.

jeff spahn

kind of sounds like I should sand blast them in my buddies cabinet, clean the crap out of them to remove any sand and then take to PC shop.
Pretty much the consensus?

BPG_Austin

The PC shop will have to prep them just prior to finishing anyway. (if they are thorough!) If they're clean Jeff, I'd just drop them off and let them do their thing. Just my .02 of course.

Gregg K

I just had mine refinished. They used a plastic bead. They special ordered the stuff. Also, it appears they used some kind of primer or something on the inside of the manifold. They did a gorgeous job. These guys were meticulous. I trust what they did. And I didn't have the fear of glass beads getting into the engine.