Manuel928S4

Hello,
I just received my intake and cam covers from the powder coated and he did a terrible job. He didn't mask anything nor cleaned any of the sand from sand blasting. What should i do with the bolt holes and all the mating surfaces? What is the best method for removing all of that media (sand?) from the inside of all the parts? Should I re-do it with a good powder coater?
Im just so angry because I even gave him copy of the pdf that is posted here in rennlist of how to correctly powdercoat the intake and obviously he didnt read them.

Thanks in anvance,
Manuel

Manuel928S4

Here are some pictures

Paddcomp

A bottle brush and water hose will get the inside clean, 2 to 3 flushes should do it.
Gasket surfaces need cleaning to a flat finish. O ring surface for the side covers not so critical.

bureau13

If you think it's perfectly clean in 2 to 3 flushes, I'd be paranoid and do more. Too many terrifying stories about this lately...

James Bailey

There have been several engines destroyed by blasting media trapped in the intake....it is NOT that easy to really get one clean. Much has been written about it here.

ltoolio

I'd go back and ask for a refund of the powder coating and funds for a replacement intake.

You are now in a position of needing to do more work just to get the mating surfaces suitable, and like James said - a lot of stories of badness in this area floating around.

The last thing you will want is to have fear in the back of your mind that your engine is going to be harmed while you drive around.

GregBBRD

Take a deep breath and relax. You've got nothing in your hands that is unique or terrible....completely typical. What people don't understand, here, is that the actual powder coating is the cheap part. The preparation after the powder coating to make the manifold suitable for use on your engine is the tougher, more time consuming, job.

Actually, your manifold looks pretty good.

No matter who does this job, the end user needs to clean the manifold before using!

The S4 manifold is much easier to clean than the S3 plenums! Much, much easier!

Start cleaning. Buy some "dental pick" style tools and clean above and around the velocity stacks....all the way around on every one! It is a simple matter to see in all the corners and in the casting areas around the velocity stacks....a flashlight and attention to detail are your friends.

Any place there is "loose" paint on the inside of the runners (I can easily see one spot, in your picture), you will need to scrape than residue off, to make sure there is no media trapped under that loose paint. Be prepared to use a small mirror to see around the corners of the runners.

You will need to replace the bearings for the internal butterfly. They never survive the powder coating process. The old bearings can be a tough job to remove. I've tried just about everything and now use a Dremel tool and a special bit to split them in half (without hitting the magnesium) to get them out. These bearings are readily available from most of the 928 parts suppliers. I keep multiple sets of them in stock.

Buy a big flat file [or a big flat (and stiff) sand paper holder] and gently work on the powder coating on the manifold until is flat. (Keep in mind that Porsche attached the side covers over the original paint....so you can do the same thing.)

If the bolt holes have media and powder coating in them, blow them out with compressed air and run a 6 x 1.0 bottoming tap into the holes. Run a 6 x 1.0 die down the injector rail studs.

Yes, you are going to spend several hours preparing your manifold....but it's not anything that all the rest of us avoid.....everyone has to do this!

Mrmerlin

after your done chasing the holes and studs and scraping out the internals,
I would suggest that at a minimum you wash the parts with simple green a bore brush then rinse the parts in hot water then blow dry them off with a120 PSI blow gun.
do this process 3 times .

NOTE sample the rinse off water to make sure that the water is indeed clean.

If you dont have a tap then use an old bolt with good threads ,
and cut 3 reliefs into the tip of the bolt add some grease or cutting oil to the threads and chase every hole.

NOTE for the fuel injector holes test fit them use Dow Corning 111 on the O rings,.
NOTE you may be able to use acetone on a rag to remove the PC on the injector holes if its too thick.

ltoolio

OK. I know better than to argue with those who are both amazingly knowledgeable, give tons of time to this board and help all of maintain our 928s (cue the Stan & Greg reference. I've been a benefactor of both of their advice, and am always thankful for their input). So, I won't even begin to argue with the guidance they have given.

But....why is it OK that the shop that the OP took his intakes to chose to not follow not verbal instructions, but printed instructions? Maintaining our 928's isn't easy (nor cheap!) and when we pay for service, especially when given a PDF to follow, we should expect that the job is done right.

As always, I mean no disrespect to Stan, Greg and everyone else who helps keep this board what it is (a fantastic resource!), but the OP shouldn't need to deal with substandard work.

Jerry Feather

Trades people are sometimes a strange lot. You take your project to them to do because you cannot do it yourself. So, their thought is commonly, "who the hell are you to tell me how to do my job." They know better than anything you might have to tell them or that you have for them to read.

Bertrand Daoust

To the OP,

Take your time and follow all the good advices here (clean-up, preparation) and everything will be good.

This intake looks very good.

Cosmo Kramer

I used this method to pull my flappy bearings after powder coat and it worked very well.

http://reutterwerk.com/forums/showthread.php?t=11581

After that was done, I filled my laundry tub with enough water to completely submerge the intake. I put it in there and scrubbed and thrashed it around, drained and repeated a few times until everything was completely clean.

kmascotto

I had my Valve covers sandblasted and powder coated. They looked... a little dirty and there seemed to be a little grit. but here is what I got out of them after cleaning them with a tooth brush. You can see the sand in the tub after the first cleaning and then the second cleaning...I didn't show pics of the third time...but after that one I did it again...just to make sure.

Tom in Austin

I used a power washer to blast the hell out of the insides from every direction. Was fairly refreshing way to get soaking wet on a 100 degree Texas afternoon ;-)

And I used a flexible brush with lots of soap suds to down through each of the runners.

GregBBRD

I agree completely. It is certainly not OK.

Just reality.

I've got the people I use for this kind of work trained. I've been behind the front counter talking with the guys that do the actual work, telling them what I want....and they still screw it up, occasionally. (I recently had a late 04 intake manifold ruined by the sandblaster....junk. This required some "additional training" by me.) Many times these people do not speak English, much less read it....so written instructions are toilet paper to them. This makes communication more difficult.

Truthfully, sending pieces out for plating, powder coating, painting, and coating is a huge pain....and sucks up more time than I could ever bill for. I do this stuff because I have to do it for my customers who have their vehicles in my shop. I never do this stuff for people that just contact me and want me to have their intake manifold done....it simply costs me more money (time) than I can bill for.

The guy behind the counter at these places generally could care less. Everyone that walks in wants super custom high end work....for the cheapest price around. Everything you tell him never gets told to the guys doing the work....they barely communicate with each other.


I have a constant stream of pieces going out for plating, painting, coating, powder coating. This does give me a certain amount of credibility. However, in reality, I know that I'm jist a pimple on their butt, in terms of volume. My current plating shop does fantastic work, most of the time. I pick up one batch and drop off another...they constantly have some work to do, for me. The reality: My stuff is such a tiny percentage of their overall work that they ask me to pay them cash....to buy lunch for the workers.