Then clean it.


I discovered a small toilet brush fits snugly in the runners, and you can get all the way thru.

I'll post photos of what came out tomorrow when im home -and- its light outside to see it.

 

To me the best way to clean after blasting is using air pressure then a thorough washing with the pressure washer used at car washes, if they did a good job powder coating it should not come off.
I would not coat the inside like the factory did, same thing with the valve cover. Remove the inside coating and leave it bare, you don’t want the paint to chip and get into your engine.
Whatever you do just clean it very well even if the shop says they cleaned it, a few S4 engines have been destroyed like that, water pressure washing will be your friend.

 

I kind of wander how much Magnesium is in there myself or what alloy did they used. I have seen old VWs with magnesium engine and transmission case burn to the ground quick due to the Magnesium burning violently after a small engine fire. However, whenever there is a picture of a S4 that was on fire, I have never seen the valve covers or intake manifold destroyed or burned, all the plastics are melted but the valve covers and intake are still intact.

could it be that they used a light weight Magnesium alloy but at the same time somthing that would not catch on fire violently in case of an engine fire?

 

I doubt it was Porsches intent to have a fire retardant alloy or they would not have used Mag at all. Wish I knew the breakdown. I've got a set of S3 cam covers in my shop that are toast because I dipped them too long in a 'magnesium safe' stripper. Was a special order, 30 gallons of the stuff. Pulled the covers out of the tank 45 min later and they were full of holes. Not swiss cheese, but granuals. The parts were too far gone to use. Luckily they were mine.. If the stripper didn't eat the mag then it sure ate something. And it didn't eat the aluminum.. What's in there? Would love if someone was able to post the official porsche data on that.

 

Parts are at the PC shop right now. He said he'd try aircraft stripper first to see if that took the corrosion off. Otherwise he's gonna sugar sand blast them, bake them then PC the. Intake in silver. Cam covers in red. Total cost $45.
Shop said, the quality of the castings is pretty poor so don't expect a glass smooth finish. Told them I really don't care how smooth it is, just want to be a consistent color and protect the metal for another 20 years. He said he'd hit the really bad pitted areas with a DA (where the castings are crappy bad quality) and smooth it out just a bit.
After PC'ing I'll take them and power wash them (got a power washer in garage so I don't have to go to car wash). Then I'll take the dremel with the scotch brite wheel and clean up the mating surfaces of the intake because they are all grey corrosion now after being off the car for three or four weeks.

I found a great write up. https://rennlist.com/forums/928-foru...onth-time.html Gave the print out to the powder coat shop.

 

Fill your bath tub and swish them around. That's what I did and didn't have any issues - aside from the wife yelling at me a bit.

 

Have spent the last week soaking, scrubbing, blasting (with water) and soaking the intake pipes and still getting grit. Now beginning to wonder if it's oxidized aluminum/ mag coming out of the pipes and not blasting media.

 

You could polish the insides of your pipes with a dremel to be sure. I read a member here did with with the flex extension on his dremel and cleaned up the insides really nicely. That would eliminate that question. That's what i am going to do when I get the parts back from PCing

 

I'm really curious about this.

My PCer guys must have done a great job, because when I got my stuff back, I couldn't get any residue of any sort out of the parts. Zero, zilch, nada. I know they used aluminum oxide blast media, but I'm not sure what all they then did to clean it all out.

When I got the parts back, I first tried just wiping various surfaces. Nothing. Flushing with water. Nothing (that I could see; kind of hard to assess without running the flush water through a filter).

I guess that's part of what I paid them for. After hearing some of these stories like yours, I'm glad I had someone else take care of this.

 

I was actually thinking of running some sort of nylon flex hone through the pipes and flushing them with pressurized hot water. These were alum/ oxide blasted, soak with simple green, baked, washed again, scrubbed, rinsed, rinsed some more, primed and painted.
Recently had cam covers blasted and while giving them a simple green soak in the tub I decided to throw the intake tubes in for good measure.
When I saw the amount of residue, I soaked the covers again by themselves... nothing. So I soaked the tubes by themselves and was able to get quite a bit out, so after a week of soaking and scrubbing, I'm still getting gritty residue, but the inside of the tubes are becoming VERY bright, so I guess it's working.
If ever I have to do this again, i will certainly pay a professional. My time is far too valuable to be spending all of it cleaning.

 

I dunno if youre cleaning anymore, rather than self honing.

?

 

What do you use for a primer, just a regular bare metal primer from Home Depot, Zinc Chromate or what?

 

Have been thinking about this all morning and began to wonder the same thing. The residue is a reddish black and definitely has some grit in it. I fear ruining the engine. With all the time and effort I've put into this project, I'd hate to foul it up.

I now have a long flexible shaft, bronze wool, zip ties and a drill. One last go at the insides of the tubes and I'll push out the dust with an alcohol-based degreaser and rags and call it done.

It's spring here in N. Cal and I want to drive my Porsche dammit!

 

The process should really be as Ed described. Lots of shops should do a great job PC'ing your parts with only a thorough cleaning and inspection by you when they're back. Hate to say it Velocipus, but I'd probably find a reputable place and have your stuff redone. If you're still getting junk coming out of your intake after a week of scrubbing Something is Wrong.

 

Try Dow 19 brush on mag treatment