Aluminum Cleaning

How do you clean cast aluminum? There are some dark patches on parts of the fan and housing. It looks like it's ditry but it may be oxidation or something. I just want to clean it really well. How? What chemical or solvent do I use. What do I NOT use?


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'83 SC

Unless there has been a change in material I haven't heard about, both the fan and housing are Magnesium, and yes they do oxidize and get discolored, rather unpleasant to the eye, in my opinion. I have only one strong caution about what NOT to use, and that would be ANYTHING ACIDIC!!! I have used spray carburetor and brake cleaners to remove any oily deposits, and rubbing compound for paint to remove the blackish-grey oxide discoloration. BUT, it is a never-ending battle! Just ask anyone with some old magnesium wheels ...

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Warren Hall
1973 911S Targa

thanx, Warren. Rubbing compound huh? I was hoping to hear about a chemical that does all the work. I'm dreamin' still...

You've made some nice calls on this board, Warren, thanx. the boiling battery for instance. You're still considering the book ideal I hope.

Interestingly, at a celebration I was hosting in college quite some time ago, someone brought a chunk of magnesium that was supposedly used by the military to illuminate bombing ranges at night. We lit that thing on fire and it illuminated everything in its direct line of sight, including hills that were many miles away! burned a hole in the asphalt too.

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'83 SC



[This message has been edited by Superman (edited 06-16-2000).]

Hi Supy (aka Jim)

I've been looking into the same issue, as the fan and the housing in my car are very ordinary. After having a look at the engine detailing tech article on this site, I've decided to have both these items either sprayed and baked or powder coated. I tried cleaning them up with car cutting compound which worked well, for a while. Now all I have to do is come up with an approapriately obnoxious colour scheme to match the guards red body work. I've seen the housing done in black and the fan in bright yellow...cool.


By the way I was horrified by the admission in a previous post that you really weren't Superman. Your not Santa going through with an identity crisis are you?

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Paul
911T'69

I used a paste, metal polish on my fan blades & housing. Took a couple of cleanings but now it looks really nice & it stays that way for several months before I need to polish it again. Mother's Metal Polish or Blue Magic Metal Polish both work well.

I saw a post where someone chromed the fan and housing and thought it looked silly. Perhaps. But the right color yellow would look killer with guards red.

My car is very nearly all original, except for tensioners, popoff. So I just want to clean it. Thanx, folks.

Paul. I am faster than a speeding 356, and that should count for something.

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'83 SC

After reading these posts, I went out to the garage and tried "Never Dull". It's a cotton wading that's been impregnated with some kind of oily cleaner. I used it previously on chrome and stainless fittings on my sailboat (long since sold). It leaves a nice thin protective coating that lasts for several months, at least in a marine environment.
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Last night, it shined up the top of the fan housing very nicely. Working down between the fan blades appears to be more of a challenge. Perhaps the brake cleaner first to remove the heavy dirt, then Never Dull for maintenance.
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I don't know about auto stores, but I know most boating stores carry the stuff. Comes in a blue tin, about pint size.
Chuck

Thanx, folks. These are great ideas. Sounds like a rubbing compound or metal polish and elbow grease is the method. I was hoping for a miracle solvent but I can get elbow grease pretty cheap and I probably have chrome polish. Never Dull sounds like a way to avoid repeating the procedure.

I wonder if these are the only magnesium parts on my car. Isn't my engine just aluminum with a little steel? Is the rubbing compound idea best for polishing aluminum too?

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'83 SC

Super, I have a Harley with a lot of alum./billet on it I use Mothers as it coats the surface and protects it. For the most part stays that way for a while. Good luck It is a lot of work.I use it on my car as well.

BTW 88'911

I tried the never dull for a while.. ran out of patience and painted the houseing and fan... Yes, guys, bright yellow and black.

Though I was considering a spiral pattern so I could "mezmerize" freinds.. Clearly an old Batman trick..

Marine stuff sounds like a winner. It is a good idea to apply some spray wax such as Audi dealers carry for spraying engines after they have been steamed. This is particularly important if you live in an area where the roads get salted. A fine dusting of this even from an apparently dry road oxidizesthe surface of clean aluminum. Does anybody know what that stuff is and if there is a generic equivilent?

The other thought I had was to have the fan and housing polished and spray baked in clear. I had this done years ago to the window frame (anod. alum.) of an MG and it ended up looking fairly stock, with a finish that lasted years. I suppose all this comes down to how much work you want to put into the project. My alt is shot so I'll have the opportunity to do all this as a detour to the fix.

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Paul
911T'69

Scott - how has the paint held up on your fan & housing? Did you clearcoat it? What kind of paint did you use? TIA,
Chris C.

I've tried the polishing route too, and like all hand metal polishing is laborious and doesn't last long. Those fan blades push a lot of air, and a fair proportion of it must have moisture and dirt in it. My metal polish of choice, Autosol works for a while and then the gunge returns. I suppose these things wern't polished from the factory, but I haven't seen a brand new one to compare. I'm thinking walnut blasting on the removed parts (to duplicate stock cast magnesium?) followed by an application of POR's new clear cote material. I haven't used it (nor can I recall it's name right now) but the advertising sounds great. It's UV resistant, sticks like you know what, is reall tough and is totally translucent. I'll be giving it a go.Can anyone remember what it's called?

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'72 911 TE

From what I understand from the original post your fan blade and housing have baked on cosmoline (spelling?). I guess they sprayed this stuff at the factory on most areas to prevent rust as a protective coating. On areas that get hot this stuff bakes on and is VERY tough to get off, BUT, It does. I entered my car in a concours last summer and was dinged points because my fan blade was dirty with this stuff. After about an hour or two of cleaning, I was able to clean all this off. All you really need is a stiff detailing brush of either brass of stainless steel. The stiffer the better for it will take less time. Rubbing with compounds and caustic cleaners just did'nt do it for my fan. Soon you will have bare magnesium which can then be polished with Never Dull or Wenol with a toothbrush for a higher shine. The outcome; All the dirty coating is removed leaving a clean matte magnesium finish. Maintenance is now simple with occasion cleaning to remove oxidation. Look is still original without the need to powdercoat. I'll post a pic as soon as I get a digital camera.

[This message has been edited by 89911 (edited 06-18-2000).]

More great input. The dark patches on my fan and housing would take FOREVER to clean with soap and water, based on my test-scrubbing. I think it's gonna take at least rubbing compound, and I do have those big metal toothbrushes if necessary.
Thanx, folks!

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'83 SC

How about simply glass/plastic bead blasting the parts, and then clear-coating them? Would that give a more or less original finish?

[Silveresrty911S]

I started doing mine a few nights ago with some Bright Boy polish from Home Depot, it worked OK but didn't shine too much. I tried a light sanding with some 600 grit paper and that seemed to work better. I guess I'll try a stainless steel brush and some Mothers polish next.
For those who have done it, what's the cost for powder coating the shroud and the fan? Ballpark costs.

Thanks, Rick

[RickM]

I sandblasted mine and cleared it several years ago. The clearcoat was the High-Temp type used for engines. It came out beautiful. Just wipe it clean when required. I'll try and take a pic and post later today.

I had started on the polishing route and gave up as I wasn't encouraged with the results.

[dkmartin]

My old concours Carrera was cleaned by me using a Dremel with the flexible attachment and wire brush bit. I used it like a pen to get into the nooks and crannies. It got all that crap off quickly and easily, however, make sure you have plenty of brush bits as they get cashed pretty quickly. Then you must polish out the fine scratches left by the brush which makes the fan a uniform, factory looking finish. That said, Carnut169 has bead blasted and powder coated his fan in Silver and it looks fantastic! Much nicer than my job- he said it cost him under $100 to do it and I would guess it is fairly permanent. It makes his engine compartment look new to the less informed. I'll try and find the picture.