Carpokes Porsche Forum

Well, in the process of swapping out my tensioner pads for my '88 S 16v, I figured I'd get my cover powder coated...

My powder coater used too aggressive of a method I guess, combined with existing corrosion and I ended up with a bit of a headache, and am now trying to source a good condition valve cover. Hoping this will seal in the meantime - currently waiting on new fuel lines from Rennbay which should arrive today

[url]

Ouch, sorry about that. Looks like they left it in a tank with non-aluminum-friendly solvent for a very long time, or blasted it with cannon balls. Did they offer to pay for it?

944S and S2 owners need to understand that these are magnesium, not aluminum, covers and magnesium demands very specific coating processes, as it is one of the most, if not the most, unstable metals around. Your typical powder coating shop will not have a clue how to deal with mag; typically only aircraft refinishers work with it on anything approaching a regular basis. There's a ton of really good information on the internet about magnesium finishing - look for a product called Prekote and forget about powder coating if you want it to last. My cover was horrific, with black magnesium oxide and peeling silver paint all over because a prior owner had rattle-canned it after stripping the very good quality factory finish off. I bead blasted, washed (really well with Dawn dish soap) and Prekoted it, then applied a few coats of clear Cerakote MC-5100. It turned out amazing (below) and won't oxidize, peel, flake off, or turn black for quite some time to come, if ever. It still feels silky smooth and looks exactly like it did the day I finished it, a year ago. You should be able to find another cover in reasonably good shape, but it probably won't be cheap. Best of luck!

icb wrote: Fri Nov 17, 2023 10:01 pm 944S and S2 owners need to understand that these are magnesium, not aluminum, covers and magnesium demands very specific coating processes, as it is one of the most, if not the most, unstable metals around. Your typical powder coating shop will not have a clue how to deal with mag; typically only aircraft refinishers work with it on anything approaching a regular basis. There's a ton of really good information on the internet about magnesium finishing - look for a product called Prekote and forget about powder coating if you want it to last. My cover was horrific, with black magnesium oxide and peeling silver paint all over because a prior owner had rattle-canned it after stripping the very good quality factory finish off. I bead blasted, washed (really well with Dawn dish soap) and Prekoted it, then applied a few coats of clear Cerakote MC-5100. It turned out amazing (below) and won't oxidize, peel, flake off, or turn black for quite some time to come, if ever. It still feels silky smooth and looks exactly like it did the day I finished it, a year ago. You should be able to find another cover in reasonably good shape, but it probably won't be cheap. Best of luck!
20220817_234359.jpg

WOW. yours did come out spectacular! Right now I’m having a bit of a hard time finding a good used part that’s free for the most part of corrosion. There’s one seller on eBay that’s selling refurbed covers, but of course at a premium.

From what it seems like, the coater went way too aggressive with the sand blaster and that’s what removed a lot of the material on mine… I put it back on the car, but of course it leaks so it’s coming back off.

icb wrote: Fri Nov 17, 2023 10:01 pm 944S and S2 owners need to understand that these are magnesium, not aluminum, covers and magnesium demands very specific coating processes, as it is one of the most, if not the most, unstable metals around. Your typical powder coating shop will not have a clue how to deal with mag; typically only aircraft refinishers work with it on anything approaching a regular basis. There's a ton of really good information on the internet about magnesium finishing - look for a product called Prekote and forget about powder coating if you want it to last. My cover was horrific, with black magnesium oxide and peeling silver paint all over because a prior owner had rattle-canned it after stripping the very good quality factory finish off. I bead blasted, washed (really well with Dawn dish soap) and Prekoted it, then applied a few coats of clear Cerakote MC-5100. It turned out amazing (below) and won't oxidize, peel, flake off, or turn black for quite some time to come, if ever. It still feels silky smooth and looks exactly like it did the day I finished it, a year ago. You should be able to find another cover in reasonably good shape, but it probably won't be cheap. Best of luck!
20220817_234359.jpg

Meant to ask as well - did you do the inside of the cover? What did the inside look like?

I did do the inside. It was pretty clean, actually. The prior owners had been using synthetic oil that must have had an awesome detergent package, because the engine was clean as a whistle inside. When I did the cover, I bead blasted and finished the inside as well, because the Cerakote is rated to handle the temperature and it's a super tough coating. I had the cover off about a year ago and it still looked perfect. I don't have a picture of the inside though.

If you still need a good valve cover, sefeing, I probably have one. I'll be out of town until 12/4, however. PM me or whatever.
MM

Yes the cover is magnesium. Ian I'm interested in your Prekote idea. Did you use any kind of aircraft stripper to get the old paint off or just the bead blast? How did you prep the metal - or does the Prekote bond straight to it? Any need to bake in an oven? Thx

michael2e wrote: Mon Nov 27, 2023 5:48 pm Yes the cover is magnesium. Ian I'm interested in your Prekote idea. Did you use any kind of aircraft stripper to get the old paint off or just the bead blast? How did you prep the metal - or does the Prekote bond straight to it? Any need to bake in an oven? Thx

Same question here!

I may have found a replacement part, but it's not perfect. I would LOVE to strip the original coating off and re-paint, or re-coat, or re-whatever, to make sure it's protected and looks as good as it can. Any advice on the best way to go about that?

michael2e wrote: Mon Nov 27, 2023 5:48 pm Yes the cover is magnesium. Ian I'm interested in your Prekote idea. Did you use any kind of aircraft stripper to get the old paint off or just the bead blast? How did you prep the metal - or does the Prekote bond straight to it? Any need to bake in an oven? Thx

The process I used is (get ready for my usual long-winded explanations):

1. Bead blast with 80 grit glass bead media at 20-30 psi. The gun should be held at a 45-60 degree angle to the work. This is to prevent the glass beads from fracturing and embedding in the magnesium; very important if you plan to also do the inside of the cover.
2. Immediately wash with blue Dawn dish detergent, warm to hot water, and a clean/new soft plastic bristle brush. Rinse with clean water. Repeat until water sheets off the surface without streaking or beading.
3. Shake or blow off excess water, then immediately spray with PreKote until saturated (PreKote comes in a spray bottle). Scrub lightly but thoroughly with the plastic brush, then rinse with water. Repeat this step at least once; you want the rinse water to sheet off as before. Avoid water spots! I think I did a final rinse with distilled water out of a jug.
4. Dry completely with a heat gun on a low setting or clean, water and oil-free compressed air.
5. Cerakote is used straight from the container, do not thin or mix with anything. Strain it first through a 325 mesh strainer, then spray using an HVLP spray gun with a 0.8mm tip at about 20 psi. The part and the room you spray in should be over 70 degrees if I remember correctly. You have to be sure that you don’t have any oil or water in the air line. Give it one good “wet” coat and let it air dry for 24 hours.

A couple of other things:
• You need (must have) a really good respirator that filters VOC’s and the like. Cerakote is the nastiest stuff I have ever smelled; it’s like it sucks all the air out of your lungs, it literally “takes your breath away”.
• I don’t remember exactly, but I think after the first bead blasting, and the cover completely stripped, I baked it at 300 degrees (F) for an hour or two to get the absorbed oil up to the surface. Then I washed it a few times with the Dawn and bead blasted it again, then continued at step 2.
• If you screw up the spray job, you can do one of two things: If you are still spraying and it’s still wet, you can clean the part off with acetone. If it’s already started to dry, let it dry completely and then bead blast it off and start again.
• This is the process I used for Cerakote MC-5100. Other Cerakote products will need different application and prep methods!

More info:
Prekote: http://pantheonchemical.com/prekote-sur ... treatment/
Cerakote: https://www.cerakote.com/shop/cerakote- ... r-aluminum