Fan/shroud blasting options/input
 

In the process of replacing my alternator I discovered my shroud was badly cracked in multiple places. Too many large cracks to reuse. I sourced a shroud with the correct casting # for my 83 Cabriolet and waiting (impatiently) for it to arrive. This shroud looks fine and reported to be untracked but it has been painted light blue with an unknown paint. While I have the fan and shroud out I thought I would get them blasted to clean them up. I tried scotch brighting the fan which got rid of most of the gunk but left some black stuff in the crevices:

http://mhackney.zenfolio.com/img/s12...33885414-4.jpg

So on to my question about blasting...

I have one local shop that does soda blasting and another that does media blasting with glass media usually. They specialize in car restorations, the soda blaster is a general blasting shop. My goal is to clean the fan and shroud up and treat them with Gibbs Brand Lubricant. I'd don't want to polish or clear coat, preferring to have a more natural patina. I understand that the media/glass will leave a bit of "tooth" or roughness to the surface but should clean them up nicely. The soda blast is much milder and it is not clear that it will clean the fan shown above - or if it can it will require significantly more time and $. I'd appreciate any input and experiences folks have.

cheers,
Michael

I glass bead them both, then bomb can clear coat with VHT High Heat clear that dries to a satin finish.

glass bead, chromate,(if magnesium), apply gibbs.

Well, there is another option.

http://forums.pelicanparts.com/porsche-911-technical-forum/806632-mark-motshagen-real-craftsman.html

And, if you haven't already searched, here's a good series of posts.:

http://forums.pelicanparts.com/porsche-911-technical-forum/282057-fan-fan-housing-polishing.html

Thanks guys. SilberUrS6, I've seen Mark's work and the F&F threads. Beautiful work Mark does but that's not the look I'm after. I'd like to keep my car "authentic" and it is basically a daily 3 season driver.

RSTarga, what's the chromate step you list? I don't recall seeing that anywhere.

cheers,
Michael

I had my fan shroud Ceramic coated in Cast Iron Gray. I chose Ceramic coating vs. powder coating because it is much thinner.

After that, I initially polished my fan but it looked to blingy for my taste and others on the board commented that it would be faded and back to original in about a year. Then I found a guy on this board (can't remember the name) who restores fans and that included beadblasting the fan, then clear coating, and then he removed the pulley and re-plated and then re-installed.

Cost of ceramic coating fan housing was $70 and cost of restoring the fan was about $125. Not dirt cheap but it looks fantastic and it was worth it to me.

Ceramic Coated Fan Housing:
http://forums.pelicanparts.com/uploa...1437437693.jpg

Bead Blasted & Cleared Fan:
http://forums.pelicanparts.com/uploa...1437437170.jpg

Put together - also ceramic coated the valve covers, same color:
http://forums.pelicanparts.com/uploa...1437437242.jpg

That does look classy. I have a time constraint to get back on the road too so even spending the time getting it blasted is a luxury!

Blasted, chromated and oiled:http://forums.pelicanparts.com/uploa...1437439999.jpg

That's the look I'm after RSTarga. How is chromated done?

the shop that works on my car did it. Its not difficult but the chemicals are a bit expensive for a one off. Dow #7 and/or Dow#19.
A lot of aviation shops can do it. If you can contact Nate Cantwell in your area, he could probably help you out. Its the original factory process that was used on all mag pieces.

Thanks for the info. I also searched here and found some great discussion.

you have to get a waxoyl type sealant on it so corrosion doesn't start again. I wipe it with Wurth HKS 1000 every once in a while.

RSTarga, I googled Wurth HKS 1000 and came up with nothing! What is that? I planned to blast and treat with Gibbs and see how it goes.

Sorry, HHS2000 Wurth product.
Gibbs should work too. I like HHS2000 because it is for high temp applications.

Thanks!

What John says. Bead blast and rattle can clear satin:

http://forums.pelicanparts.com/uploa...1437497596.jpg

Currently in a state of partial dis-assembly - doing a valve adjust...

-C

I used glass bead on mine and found it too aggressive. It was aggressive as sand IMO.

I'm a huge fan of soda.

Tippy, that's my concern too. But at the other end of the scale is - can soda blast clean up the fan I show in the first post? Without taking too many hours of labor?

I tried Soda - would have taken a week. Between bead blast and soda is Walnut Hulls. Available at sandblast supply houses, or for a one-off @ HF
-C

I sand blasted and duracoated at home. Not a difficult process

http://i30.photobucket.com/albums/c3...psmrn5qsx6.jpg