syoo8

Not to be argumentative... but B17 contains a warning that specifically warns against use with magnesium. I wouldn't use B17 with our parts.

bills928

Your powdercoater should have known better than to coat those flange surfaces..... When I had my intake done,
the first question he asked was, "What areas have gaskets attached" so he could mask them.
Maybe he can blast the flanges without damaging the rest of the part ..... And he should do it for free.

spooledx2

See goes,to prove you learn something new everyday... I didn't know that. Thanks for the heads up, good to know!

Ramon

user8

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BC

That is some "wham bam" thank you mam PC-ing. Those mating surfaces should have clearly been avoided by anyone who had their eyes open.

Don't like giving bad news but that is going to be hours of work for you.

The flat surfaces are easy - just tape some sandpaper down on flat steel and slide back and forth without rocking.

BPG_Austin

desertspirit, I think you'll be OK since you have decided to run your parts. Masking 85-86 intakes takes a lot of time, is difficult, and should have been reflected in your cost. I think you'll be fine blocking out the bottoms of the intake runners as BC and others have said. Porsche didn't mask the intake runners originally as you can see the overspray into the tubes. They did last 25 years before starting to flake off. I'd personally leave the overspray (on the upper runners) and check the condition of the PC when you pull the plenums off during a sparkplug change. The overspray in the insides of the cam covers around the spark plug holes will also be OK as a large rubber grommet covers the area. I'd block it smooth and feather any rough areas though. The waterbridge and oil filler neck really should have been masked and it will probably take some sanding to get them to fit.
Also, as others have said, do not use B-17, or B-12. I've used both and also contacted the manufacturer. They'll destroy your castings in less than an hr of submersion. do NOT use under any circumstance. The exception is the waterbridge and oil filler which are alumiunum and thus safe to submerge in B17 or B12. Klean-strip and other box store strippers will strip your parts. But, they're messy, toxic, take forever.. Use spray on only, no submersions. OK to do once, but you'll never want to do it again. Blasting off PC on these castings is also not a good idea. The PC is generally tougher than the castings and its very easy to destroy, warp, blow holes through before you remove the PC. I've made all the mistakes above, both blasting and chemical stripping. It can be done, but best left to a professional. and even that.. Meh, I don't know that I would.
I'd say the take-away on these particular parts would be to block out the areas you can to make things fit/seal properly and WASH them thoroughly. The washing really being the most important part. Just my .02. Oh, and, on a positive note, GREAT selection on finish. The silver vein is a really cool effect. Huge plus is that it does help to hide the casting blemishes.

Ben

Ed Scherer

You know, given how much work it'll be to either redo these or carefully remove the coating from the mating surfaces, I'd have to consider the possibility of just seeing if you could get them to seal, using Hondabond/Yamabond between the gaskets and the coating. What's there to lose (other than the time)?

Removing the coating from the large flat areas might not be too bad (although I seem to remember that these coatings really bond, almost like epoxy), but I wouldn't relish having to remove it from the channels (like on the water bridge and cam covers).

How sure is everyone that you can't get a seal on a coated surface?

Despite taking a lot of time to research this topic myself (and sharing the information on the already-mentioned Powder coating intake/cam covers/etc. best practices thread), I don't believe I ever heard anybody say that they experienced a sealing failure when not masking everything the way that is recommended in that thread.

Glen McCartney

Get some aircraft stripper and a small brush, mask off the pieces and work slowly, you should be able to clean the gasket surfaces down to bare metal without affecting the rest of the piece. I did this on my son's 3 piece wheels before reassembling them when powder coater coated everything, reassembled, and they were true and held air for 3 years now.

Ed Scherer

Plastic razor blades might be useful, too.

BPG_Austin

Very valid point Ed, I fully agree with you. Just to add to that, I don't think I've ever heard of reported engine damage due to flaking off original coating. (I do believe any GTS intake is potentially a ticking timebomb, but that's another topic due to that specific coating.)

danglerb

These are great for detailing the car, going after sap, etc., powder coat is way too hard to even notice you are using them. I like the much smaller holder originally by Hyde Manufacturing, now sold by Stanley and various hecho y china, Amazon I think still carries the made in USA part for a couple bucks.

BTW I wasn't suggesting "new" parts, just fresh used ones.

Guessing all the air seals will be "OK", and all the liquid seals leak, sooner or later.

Jerry Feather

If it were me I think I would try a heat gun. Simply heat the offending coating back up to its curing temp, or close, and scrape it off. I don't think the heat will damage the coating that is not getting scraped off and the process will likely leave a better finished edge on the coating that remains.

Hilton

I have a large offcut from granite kitchen bench.. makes a great flat surface for sanding, and its semi-portable (its about 3x1.5 feet). I had to sand the old glue off a rear view mirror metal mounting button a few days ago.

I'd be worried that steel will bend?

Leon Speed

Back in the day an old trick to shave a cylinder head was to use a mirror for a flat surface.

user8

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