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914World.com _ 914World Garage _ Refinishing: Magnesium Fan Shroud & Transmission Case
Posted by: 914 7T3 Oct 19 2017, 01:21 PM
In reading up on some older threads, it has been stated that the Fan Shroud & Transmission Cases are Magnesium.
I have the shroud out for media blasting along with the engine tin etc....
Once completed should the shroud be finished with a high heat clear paint such as a Krylon that is rated up to 600 degrees. Also should there be any type of prep done between these steps. I want it to look right, but do not know if they were coated from the factory or should be left in the original finish.
On that note the transmission case will not be blasted, but it was suggested that it be cleaned up with a wire brush and steel wool. Is that the correct way to go and similar to the shroud does it require a clear painted finish or just leave it alone. Here is a pic of a small section that I went over with steel wool after degreasing.
Lastly, once the Muffler is blasted, does that require a high heat ceramic coating? If I do not coat it, will that just accelerate any future surface corrosion? Don't really want to spend 1/2 the value of a new muffler heat coating the old one.
Any advice?
Posted by: Dr Evil Oct 19 2017, 01:43 PM
I cannot speak to the shroud as I do not know what they left the factory with, but the case for the trans had Tectyl coating on it. It was a corrosion preventative, but it wore off in a few months from what I have read/been told. I have never bought any or reapplied it. The product that many like is called Gibbs, I don't have a link available currently. It last longer. However, from my personal experience on the rare occasion that I do clean and paint a case, I just used good quality spray paint of what ever desired color and finish I wanted and it has been fine. The key is that you do want to protect the trans case, particularly if you are anywhere there is salt, or wet environments. I am originally from San Diego and lived in PA and OH and the East coast stuff is way more corroded than the West coast on average.
Posted by: 914 7T3 Oct 19 2017, 01:49 PM
The key is that you do want to protect the trans case, particularly if you are anywhere there is salt, or wet environments. I am originally from San Diego and lived in PA and OH and the East coast stuff is way more corroded than the West coast on average.
Thanks Doc, forgot to mention that the car upon completion will be a bit of a garage Queen. She won't come out in the rain...ever and hope not to have to drive through any puddles.
Posted by: Elliot Cannon Oct 19 2017, 01:59 PM
Paint it black. 
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Posted by: The Cabinetmaker Oct 19 2017, 02:04 PM
I've cleaned and polished a few shrouds. They don't last without a protective coating, and most clear coats don't hold well either. I spray them with an industrial enamel the same color as the grey intake runners. They stay very nice that way.
Posted by: 914 7T3 Oct 19 2017, 02:14 PM
Paint it black.
"I wanna see it painted, painted black
Black as night, black as coal
I wanna see the sun blotted out from the sky
I wanna see it painted, painted, painted, painted black"
However, trying to keep it original looking.
Posted by: porschetub Oct 19 2017, 02:14 PM
I have seen fan housing done a flat silver (alloy look) paint after blasting....looks pretty good IMO,I honestly didn't know they were made from magnesium ,always thought they were alloy 
.
I wouldn't use a wire brush or wire wool on the trans case because you will burnish metal particles into the surface of the magnesium ,use the 3m green pads and their wheels you can put on a drill or die grinder,prep the surface super clean then put your chosen clearcoat on.
Good luck.
Posted by: cal44 Oct 19 2017, 02:56 PM
As the others mentioned.......wire brush?.....NO
Like Dr. Evil I'm also from San Diego.......wait......I still live here.
Bronze wool, I use fine grade. It's a secret weapon few car guys know about.
The boating pros use the bronze as it doesn't rust when tiny particles are not cleaned up and puts a smooooth finish to the surface. It does wonders on old chrome, doesn't dig in to aluminum either. Been using it for decades. If you can't find it locally, order on line and make sure to shop the price, wide variations.
As for coatings, PRO clear can spray, Rustoluem clear. We just did a '66 Bronco Roadster that had all original factory chalk marks thru out. We did five layers of Rustoleum clear. It had a very low gloss and the marks are now safe and quite visible.
Por-15 is supposed to have a crystal clear coating but I have yet to give it a go.
Do not use Por-15 clear rust sealer.
We use Kano Labs degreaser as our first step.
Posted by: mgphoto Oct 19 2017, 03:05 PM
Sand blasted my fan shroud than power coat silver.
Posted by: altitude411 Oct 19 2017, 04:08 PM
That fan shroud looks great 
Here is my trans getting the treatment... lots of elbow grease to remove road grime.
[attachmentid=624264]
[attachmentid=624265]
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Posted by: mb911 Oct 19 2017, 04:22 PM
This is cerakote on magnesium.. It is a ceramic paint.. Very durable..
Posted by: mgphoto Oct 19 2017, 04:49 PM
That fan shroud looks great
Here is my trans getting the treatment... lots of elbow grease to remove road grime.[attachmentid=624264]
[attachmentid=624265]
Beautiful!
But you're gonna cover the surface with the wax Dr. E talked about?
Posted by: mepstein Oct 19 2017, 04:53 PM
This is cerakote on magnesium.. It is a ceramic paint.. Very durable..
We’ve been using it more and more at the shop. You do need a real respirator to spray it. Strong stuff.
Posted by: mgphoto Oct 19 2017, 04:53 PM
This is cerakote on magnesium.. It is a ceramic paint.. Very durable..
Very nice, I love the look.
Did you do it yourself, rattle can?
Posted by: DM_2000 Oct 19 2017, 05:01 PM
Paint would be fine. On steel wheels I've used machine gray then before it drys, dusted stainless over top to give a slight bit of sparkle ( both were Rustoleum in a spray can. ) The gray was too bland , stainless too bright. Argent is a common wheel color but that was a bit too bright.
Posted by: mb911 Oct 19 2017, 05:51 PM
This is cerakote on magnesium.. It is a ceramic paint.. Very durable..
Very nice, I love the look.
Did you do it yourself, rattle can?
I sprayed it with my sata automotive sprayer. I have a bunch more paint. If anyone needs something sprayed.
Posted by: mb911 Oct 19 2017, 06:09 PM
Here are my valve covers sprayed as well.. 
Posted by: eric914 Oct 20 2017, 11:07 AM
I did a little digging on what the aircraft and marine industry uses and ended doing the final wash on the raw case with Prekote surface pretreatment then priming with Zinc Chromate primer. Not sure what ill do for a top coat yet.
Posted by: Dr Evil Oct 20 2017, 12:57 PM
I did a little digging on what the aircraft and marine industry uses and ended doing the final wash on the raw case with Prekote surface pretreatment then priming with Zinc Chromate primer. Not sure what ill do for a top coat yet.
Man, you are gonna be done pretty quick tomorrow as the cleaning is the longest part. I remember zinc chromate when I was working on aircraft and ships. The MSDS made it look like really nasty stuff. Should protect very well.
Posted by: cuddyk Oct 20 2017, 01:07 PM
Wow...nice to have a spotless case. Took me 8 hours with a toothbrush and mineral spirits to get mine clean.
I used "alumi-blast" paint by Seymour. Here's a link...
https://www.amazon.com/Seymour-16-055-Alumi-Blast-Paint/dp/B003V5BPKU
Posted by: mepstein Oct 20 2017, 01:21 PM
Playing with cerakote at the shop.
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Posted by: mgphoto Oct 20 2017, 02:07 PM
Playing with cerakote at the shop.
Talk about bling!
Big heavy chain and you can go clubbing!!
Posted by: Mueller Oct 20 2017, 02:14 PM
Playing with cerakote at the shop.
Dang, that looks good!
Posted by: burton73 Oct 20 2017, 02:22 PM
https://www.cerakotehightemp.com/testing/
Testing of Cerakote High Temp
Bob B
Posted by: 914 7T3 Oct 20 2017, 07:43 PM
Thanks for chiming in everyone and the photos look great. Will be going ceramic titanium on the Muffler.
Spoke to a high end 911 restorer earlier today and confirmed that brass wool is the way to go on the transmission case. Also learned that media blasting may be too harsh for the fan shroud so I now have a line on someone that can do tumble blasting that is more gentle.
Here's the kicker, the recommendation is not to coat the magnesium with any paint or clear finish, but to liberally spray it with WD-40 for a natural finish and leave it alone.
As good as all of the painted photos look, I will go with the unfinished look.
Posted by: mepstein Oct 20 2017, 08:04 PM
Gibbs works better than WD-40 for longevity.
Posted by: 914 7T3 Oct 20 2017, 09:49 PM
Here are some photos of the case from the 76 911 SC that sold at Gooding in Scottsdale this January for $93K
Posted by: 914_teener Oct 20 2017, 09:51 PM
Thanks for chiming in everyone and the photos look great. Will be going ceramic titanium on the Muffler.
Spoke to a high end 911 restorer earlier today and confirmed that brass wool is the way to go on the transmission case. Also learned that media blasting may be too harsh for the fan shroud so I now have a line on someone that can do tumble blasting that is more gentle.
Here's the kicker, the recommendation is not to coat the magnesium with any paint or clear finish, but to liberally spray it with WD-40 for a natural finish and leave it alone.
As good as all of the painted photos look, I will go with the unfinished look.
I saw no harm and couldn't think of any on powder coating the fan shroud. I brass wheeled the trans case and used Gibbs as described keep the mag from corroding. The trans gets hot so I didn't want any insulation to inhibit radiation of heat away from it.
It's probably not much but with air cooled motors every little bit helps.
Posted by: worn Oct 21 2017, 04:09 AM
I did a little digging on what the aircraft and marine industry uses and ended doing the final wash on the raw case with Prekote surface pretreatment then priming with Zinc Chromate primer. Not sure what ill do for a top coat yet.
That is what I chose. From aircraft spruce.
Posted by: toolguy Oct 21 2017, 09:27 AM
You should look into Boshield T-9 from Boeing as
a preservative for bare Magnesium. Just saying. . .
Posted by: rgalla9146 Oct 21 2017, 11:52 AM
Nothing screams 'beware' louder than a brightly painted VW or Porsche engine or trans.
Applying a legitimate preservative ? that's another story.
I do like the Cerakote on Bens valve covers. Perfect for magnesium wheels.
Posted by: mepstein Oct 21 2017, 01:06 PM
Nothing screams 'beware' louder than a brightly painted VW or Porsche engine or trans.
Applying a legitimate preservative ? that's another story.
I do like the Cerakote on Bens valve covers. Perfect for magnesium wheels.
Rory secretly covets our chrome trans.
Posted by: raynekat Oct 21 2017, 09:24 PM
Ben, your valve covers look super.
What did you paint them with?
Here are my valve covers sprayed as well..
Posted by: rgalla9146 Oct 22 2017, 06:13 AM
Nothing screams 'beware' louder than a brightly painted VW or Porsche engine or trans.
Applying a legitimate preservative ? that's another story.
I do like the Cerakote on Bens valve covers. Perfect for magnesium wheels.
Rory secretly covets our chrome trans.
Ok, Ok, Mark I'll admit it. It looks good.
Posted by: Perry Kiehl Oct 22 2017, 02:38 PM
Media blast with walnut shells, clean with solvent, paint with high temp clear or unobtrusive gray/silver/cast metal high temp paint.
Bright silver looks great! .....on a VW sand rail or Meyers Manx.
Posted by: Rav914 Oct 22 2017, 04:35 PM
Here are some photos of the case from the 76 911 SC that sold at Gooding in Scottsdale this January for $93K
Wait? What? $93K?
For a '76S?
Posted by: Guberif Oct 23 2017, 12:44 PM
New to this and can't figure out how to upload compressed pics. Still too big i guess. If you want you can just pm me and I'll email you my pics.
I got mine shining like a diamond! with no paint, but yet still protected.
Anyway, I just did both the fan shrouds, trany, h.e.'s & some select heater ducting last summer with good old fashioned elbow grease, dremmel with buffing pads, die grinder with several soft scotch brite pad, mothers polish seemed to work the best out of the 6 different types of polish I had tried, mothers polishing cone to get in on all the nooks and crannies and toothbrushes and a flexible narrow putty knife! I protected mine with diamond clear from eastwood, (father was a chemist) this stuff is relatively high temp and especially formulated for bare metal.
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