Repro OR Resto? Magnesium Fan + Housing

[han]

Seen some posts here about restored fan + housing for 911. I have a 1988 coupe, and my fan housing has a crack (really subtle and not all the way thru - see pic) in one of the support arms. I noticed this after I pulled the fan so that I could sand the oxidation off and bring back some shine.

Now I'm debating whether to:
A) Do the best I can with sanding/polishing and put everything back (original fan + housing). Ignore the crack - and hope it doesn't get worse/completely break?

B) Pay/ship to a restorer (which one? I think some are retired/gone) to repair and restore my cracked housing - also polish/powder coat/paint? to look 'good as new'?

C) Buy a repro Magnesium (or are the Aluminum ones "better" yet heavier). Also which repro supplier: FVD? Vertex? Carpoint? Other? Pelican sells the EPS AL ones.

Thanks for opinions from those who have gone through this journey before...

[Mixed76]

Pics help, see my recent post here

https://r.tapatalk.com/shareLink/topic?url=https%3A%2F%2Fforums%2Epelicanparts%2Eco m%2Fshowthread%2Ephp%3Ft%3D1059881&share_tid=1059881&share_fid=844&share_type=t&link_source=app

Sent from my Nokia 7.1 using Tapatalk

[han]

Not sure if my pic from orig post worked (of cracked housing). 2nd try...

[Jonny042]

Minor.

[Pedro '84 Coupe]

This can be repaired. Contact user mb911 (Ben) to see if he can help you. If for some reason he can't fix it, I recommend the repro mag housing from Carpoint. I got mine through DC Automotive but they sell them on eBay too. Am very happy with it.

[Flojo]

Dremel the crack to relieve the tension, then JB weld. reinforce ALL similar areas.
JB weld is fit for ceramic coating.

just did mine that way.

edit: bare in mind the alternator is aprox 20kg of weight hanging in there!
I never understood why Porsche designe the fan with just 4 brackets…

old compound, many heat cycles, abrasive dirt and vibrations will harm the fan a lot

[ClickClickBoom]

That is just the tip of the iceberg.
Read this if you like:
Fan Shroud
Any time/money you spend on that housing is wasted. That housing may last 1 year or 20 more, you won’t know until it fails.

[ClickClickBoom]

Originally Posted by Flojo

Dremel the crack to relieve the tension, then JB weld. reinforce ALL similar areas.
JB weld is fit for ceramic coating.

just did mine that way.

edit: bare in mind the alternator is aprox 20kg of weight hanging in there!
I never understood why Porsche designe the fan with just 4 brackets…

old compound, many heat cycles, abrasive dirt and vibrations will harm the fan a lot

Water and road debris combine to create an electrolyte and that causes the corrosion damage. I have seen aircraft parts cast from magnesium that were 75 years old and still looked like new. They were treated with a conversion coating (Dow #7)and painted with zinc chromate paint. Unless a conversion process is used, nothing, repeat nothing will adhere to the surface, you will be JB Welding beach sand to the beach.

[ClickClickBoom]

Dow #7
https://www.chemical-supermarket.com/product.php?productid=652

“Introduction:

Magnesium and its alloys are more galvanically active than even zinc

on the galvanic series. Magnesium will form a strong galvanic cell with

every other metal it comes into contact with and is always sacrificial.

When magnesium corrosion is detected, it requires immediate attention

or the corrosion will spread throughout the entire structure. Therefore,

these alloys must be properly protected from corrosion damage.”

https://www.chemical-supermarket.com/product.php?productid=654&cat=165&page=

The danger from these chems cannot be underestimated, so ask, why would they perfect this type of process if it weren’t necessary.

[Pedro '84 Coupe]

The alternator does weigh a ton!

I didn't treat the new housing. Just coated it and the fan with Gibbs Brand oil hoping it lasts another 36 years

[han]

Thanks all for your informative posts and opinions. I know that dealing with 30+ yrs old Mg car parts is not the easiest/most common car issue on the planet. But this is (at least one notable item) what makes our air-cooled cars so special.

I think I'm going to go the outsourced resto route (at least until I experience total fan/housing failure). It seems like the best route to 'preservation'. To pay the info forward, here's a list of the resources I gathered from reading forum posts and google searches:

I. DIY "Light" resto - aka Dow #7/Sanchem/Mg Conversion + JB weld cracks (from ClickClickBoom post): Cost = approx $200+, Labor = wknd project, Lifespan = ? (maybe brief, maybe longer depending on extend of corrosion and cracks), Would also still need some protection (clear coat/power coat/ceracote/etc.) after the conversion process., Con: messy and potentially toxic, JB weld is suspect for longevity, no 'strengthening' happening here.
Links: Fan Shroud
https://www.chemical-supermarket.com/product.php?productid=652

II. Outsource resto - aka pay someone more experienced than me to do this: Cost = approx $500, Labor = remove/pack/ship fan + housing, Lifespan = ? (maybe longer than DIY), Turnkey process = complete fan that was orig to car and will likely have no fitment issues after process, Con: more $ than DIY but less work. Providers of outsource fan resto service:
a) Mark Motshagen (mots356@yahoo.com) - now retired?
b) Tru6/Shaun (shaun@tru-6.com) - Cambridge, MA Tru6 Restoration & Design
c) FlyingJay (flyingjay1@gmail.com) - So Cal/San Diego Area
d) mb911 (ben mbconsulting21@gmail.com) https://914-6werkshop.com/ located in WI, Only does weld repairs (not refinisher)?

III. Repro replacement (available in Mg or Al) - aka get a 'new' one: Cost = $1000+ (depending on Mg vs Al), Labor = online order + replace fan, Lifespan = longest, as these are effectively 'new' parts, Thorough process = completely new parts, Con: might not be exact fit/finish as orig, some suppliers have poor qlty parts, Al = 4x heavier than Mg (but would likely last longer). Providers of repros:
a) Vertex https://www.**********.com/
b) FVD https://www.fvd.net/us-en
c) PelicanParts/EPS (Al only)
d) Carpoint (ebay/DC Automotive)


Gotta keep em driving!

[han]

Cr*p!

Found more cracks in the housing (from the backside) - I think we've 'found' the iceberg cap'n Also - alternator is really 'stuck' in there, and I don't want to bang on the alt studs for fear of FURTHER housing damage.

I'm now thinking plan 'C' = get a new housing from Carpoint/DC
Auto

[ClickClickBoom]

Iceberg indeed! Remember magnesium needs a conversion coating, period!
Choices are:
Dow #7- toxic as all get out
Sanchem- pour down the drain with no issues
Until you convert the surface EVERY coating will ultimately fail, there is no way around this unless you keep the car/shroud in an inert atmosphere.
This is basic industry standards, some who drive a couple thousand miles in perfect weather might be getting good results, but if you drive year round(me), the process accelerates. Also the auto industry considers a car that lives within 2-300 miles of a large body of water(Pacific Ocean) is in a hostile environment.
If you look at the surface closely, inside the circle is corrosion and every pit is old corrosion. All it takes is a pit on a grain boundary line and you get intergranular corrosion.
Not a metallurgist, but I have stayed in a Holiday Inn Express once.

https://www.intechopen.com/books/magnesium-alloys-selected-issue/corrosion-types-of-magnesium-alloys

[han]

Thanks CCB!

On a clear day, I can see the Pacific Ocean from my house ;-) And most of my drives are down Hwy 1

Luckily for me, this is not a daily driver, so I can take some time to think about my plan of action.

I've been emailing Jay and he seems to think (from pics) that the housing is worth welding/repair. I hate to buy new rather than resto original, but sometimes the cost savings/life span trade-off is too wobbly to justify resto....

[Mixed76]

Don't bang on the alternator bolts. Hold the assembly with the fan facing down and drop the housing from a few inches onto 2x4s. Read that on here somewhere.

I did that three times before the alternator dropped free. Minor corrosion between the alternator and the housing keeping it stuck.

I took the fan off the shaft first, not sure if it matters.

Dan

Sent from my Nokia 7.1 using Tapatalk

[ClickClickBoom]

Originally Posted by han

Thanks CCB!

On a clear day, I can see the Pacific Ocean from my house ;-) And most of my drives are down Hwy 1

Luckily for me, this is not a daily driver, so I can take some time to think about my plan of action.

I've been emailing Jay and he seems to think (from pics) that the housing is worth welding/repair. I hate to buy new rather than resto original, but sometimes the cost savings/life span trade-off is too wobbly to justify resto....

If those are on the surface, much more lies below. All said, I would get the aluminum and have it anodized then coated. Mg is cool but the maintenance is too high. Your shroud is toast. Sorry, but it lasted a while anyways.

[911pcars]

Be aware that if the drive belt adjustment is too tight, it puts additional load on the whole assembly. Cracking could be one symptom. Otherwise, perhaps unbalanced. 911 cooling fans have been in service since the late 60's and I'm guessing they're either mostly alive or corroded. While there are examples of cracked fans/fan housings, it hasn't been a historic failure issue.

Sherwood

[RFP]

I have the Vertex housing and I am quite pleased with it. I have a restored fan done by "Flying Jay" ... Great work.

[Tony V]

Anyone know if Mark M is still refurbishing fans and housings?
Finally ready to do mine.
Thanks,

[FrankM_]

Originally Posted by han

Cr*p!

Found more cracks in the housing (from the backside) - I think we've 'found' the iceberg cap'n Also - alternator is really 'stuck' in there, and I don't want to bang on the alt studs for fear of FURTHER housing damage.

I'm now thinking plan 'C' = get a new housing from Carpoint/DC
Auto

Hi,

I am in more or less the same situation (less cracks, but anyhow, issues). Did you ever get the carpoint one ? Can you say something about their quality ?
Colour wise how does it look vs the original ?