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Are You Driving a Bomb? [ mag fan '64-9 ]
Posted by: vairmech ()
Date: December 12, 2017 06:14PM

If you have a magnesium cooling fan then you are! I will show you the why and the how. I have been finding more and more of these as they get older. Some of you in the fair weather states may not see this as much but you still need to keep watch.

As you know the 64-9 cooling fans are made of magnesium, Magnesium has some issues and the major one is called intergranular corrosion. I will show you what it looks like so you can identify it. It really depends on how much you have and where it is at if the fan can stay in service. I have had some fans that just had some little pin spots in the middle of a flat surface and when I bead blasted it left a little divot but was not a structural defect so I painted and used it.
Well here you go, I started cleaning this fan from a 64. I didn't have high hopes for it as I saw the signs as you will too.


As I look a little farther I see this, This car was driven to me! How long do you think this would have lasted on the road?


Then when you turn it over there were these ridges that almost looked like casting lines until I hit them with the bead blaster and here is what you get.


Here s a closer look at where one of the ridges were and you can see the magnesium flaking and then there is a dark under that layer. That is the intergranualr corrosion! You can see the ridge that I was talking about continue to the mounting flange. Yes that is a crack running to the center.


Here is a closer look at what the ridge looked like.


I cleaned a little more and this didn't really show up until I hit it with the bead blaster! I really don't know what is holding that fin on the fan.



I know I have posted these pictures before but I am going to put these here again so you can see the aftermath of a fan exploding while you are driving at 60 mph.














Keep checking those magnesium fans.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com



Edited 1 time(s). Last edit at 12/13/2017 07:33PM by MattNall.

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Re: Are You Driving a Bomb?
Posted by: stitch ()
Date: December 12, 2017 06:18PM

Thanks for the nightmares! ggg

"If you can't fix it with a Hammer, you have an Electrical problem."
Stitch...
Schertz, Texas.
(Smallish town/burg 17 mi. NE of San Antonio)

!967.. 4th body
8th off the line

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Re: Are You Driving a Bomb?
Posted by: RKF ()
Date: December 12, 2017 06:44PM

Until today I had never thought about exploding fans. Today, I have been warned twice that fans in my cars may explode.

Early this morning I received an email from England advising me that the fan in my 1917 Overland is prone to coming apart without warning.

Then, on this forum, I learn that the mag fan in my Corvair might also disintegrate while going down the highway.

All of the sudden, I have two more things to worry about.

Good information, though. I appreciate the heads-up.

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Re: Are You Driving a Bomb?
Posted by: Tumanator ()
Date: December 12, 2017 06:46PM

Thank you very much for sharing this knowledge! I now know what to look for - and most definitely thanks to your re-posted pictures - why its important to know!

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Re: Are You Driving a Bomb?
Posted by: irfgt ()
Date: December 12, 2017 06:58PM

Think GM should issue a recall?

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Re: Are You Driving a Bomb?
Posted by: 63turbo ()
Date: December 12, 2017 07:23PM

I had heard that the mag fan could explode, I had not actually seen one that had exploded... I'm glad I made mine out of aluminum!smiling smiley corrosion of any kind is seriously a bad deal, as once it starts, it creates stress concentrators, and the stress concentrators speed the corrosion up in a feedback loop of sorts
until Kaboom!

------------------------------------

Kevin Nash
Friday Harbor Washington
63 Spyder, Daily driver, EFI read about my project here: [corvaircenter.com]
first test start on EFI here:[www.youtube.com]
first official EFI boost test here:[www.youtube.com]
My new fan! [corvaircenter.com]
engine less 62 Spyder
Canadian 64 Monza Parts car



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Re: Are You Driving a Bomb?
Posted by: American Mel ()
Date: December 12, 2017 07:38PM

Good info.

BUT, it also brings up a question that I have had for a LOOOONG time.

We have all heard the story of the "experimental" Delrin fan that GM was working on that turned out to be a bad idea.

But now, some 50+ years down the road, there have been some incredible advances in plastics.
Why hasn't anyone made a new lightweight fan foe our cars?

I know that Kevin is working on a really cool looking aluminum fan, but undoubtedly something that custom is going to have a really custom price also.

Why not a proven design(ie. the stock fan) but in a modern lightweight, and inexpensive (acid/hydrogen sulphide resistant) plastic?

Would something made on a 3d printer be able to withstand the forces of being spun at high RPMs?

.
-----------------------------------------------
WA. state, 1 mile south of the Canadian border,
I am not at the end of the world, but you can see it from here.
'66 Monza Coupe - 4spd, 140 Daily driver beater
'67 Monza Vert. - PG, 140 Daily driver beater

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Re: Are You Driving a Bomb?
Posted by: Timothy Shortle ()
Date: December 12, 2017 08:23PM

Does this mean the 1960-1963 steel fan is the one to have? Of course SW Colorado is a fair weather area. This morning temp was 16.

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Re: Are You Driving a Bomb?
Posted by: 63turbo ()
Date: December 12, 2017 08:39PM

The Big reason I didn't copy the stock fan is that it is seriously inefficient
when used in an "open shroud" like the stock configuration. It is only 28-29%
efficient when it ought to be 60%, and it cannot get to those kind of efficiencies with the stock shroud...to get to 60% with a straight bladed radial fan, there needs to be a whole bunch of vanes around the outside of the fan to make it work properly. There are some major problems with doing something like that. It is extremely difficult to get good uniform airflow distribution to all cylinders and even if you get the distribution perfect the
efficiency peak is very peaky and narrow, and the efficiency is limited to
60%. My fan doesn't need any of that stuff to get the kind of efficiency that is expected, which should be 60-75%. At that kind of efficiency, the horsepower
usage is less than half of what the stock fan uses, and if it is properly sized
could be geared down a bunch... making the weight concern mostly moot even
if it somehow ended up heavier than the stock one in production form.
If it was made from a more modern grade of magnesium it would weigh around 30%
less- .84 lbs, and if it can be done from a newer composite, it would weigh something like .5 lbs.

------------------------------------

Kevin Nash
Friday Harbor Washington
63 Spyder, Daily driver, EFI read about my project here: [corvaircenter.com]
first test start on EFI here:[www.youtube.com]
first official EFI boost test here:[www.youtube.com]
My new fan! [corvaircenter.com]
engine less 62 Spyder
Canadian 64 Monza Parts car



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Re: Are You Driving a Bomb?
Posted by: 66vairman ()
Date: December 12, 2017 08:54PM

Thanks Ken for the post.

If the picture color is correct that fan metal is a light brown, that indicates the magnesium has oxidized. GM painted the fans with a durable sealer. Once that fails the magnesium starts to oxide and that oxide is hygroscopic (absorbs moisture) which aggravates the problem.

I've cleaned up and painted a few west coast fans and so far I haven't seen any with oxidation problems, or cracks. Once the fan is stripped you DO NOT LET IT SIT AROUND before painting as it will oxidize in short order.

I guess the moral of the story is to pull the fan, inspect, clean, and repaint it.

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Re: Are You Driving a Bomb?
Posted by: vairmech ()
Date: December 13, 2017 03:59AM

Kevin & Vairman, The magnesium can be perfectly sealed and it still can corrode. That is why it is called INTERGRANULAR. It starts within the grains of the magnesium.

Believe it or not P-51 Mustangs have the same issue with the center spar assy.

Aluminum is different where the corrosion starts on the outside and works in.

Yes there was an experimental Delrin fan but the hydrogen from an overcharged battery would react with it and produce some kind of smelly gas. That is also why the late model cars had battery vent caps with tubes that went overboard.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Are You Driving a Bomb?
Posted by: vairmech ()
Date: December 13, 2017 04:00AM

OH, BTW, I didn't put this out there to scare anyone but rather to make you aware and to look at your fan now and then.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Are You Driving a Bomb?
Posted by: azdave ()
Date: December 13, 2017 04:48AM

vairmech Wrote:
-------------------------------------------------------
> ...I didn't put this out there to scare anyone...

Your thread title begs to differ grinning smiley (but it is good to let people know to always be vigilant when it comes to safety).


Dave W. / Gilbert Arizona
66 Corsa 140 4-speed w/factory A/C
66 Corsa 140 4-speed w/factory A/C
66 Corsa 140 4-speed
65 Corsa 140 4-speed
66 Corsa 455 Toro V8
65 Monza 455 Toro V8
65 Monza 110 Convertible
65 Monza 4DR 140 PG w/factory A/C
65 Monza 4DR EJ20T w/5-speed




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Re: Are You Driving a Bomb?
Posted by: gnvair ()
Date: December 13, 2017 06:07AM

63turbo Wrote:
-------------------------------------------------------
> The Big reason I didn't copy the stock fan is that
> it is seriously inefficient
> when used in an "open shroud" like the stock
> configuration. It is only 28-29%
> efficient when it ought to be 60%, and it cannot
> get to those kind of efficiencies with the stock
> shroud...to get to 60% with a straight bladed
> radial fan, there needs to be a whole bunch of
> vanes around the outside of the fan to make it
> work properly. There are some major problems with
> doing something like that. It is extremely
> difficult to get good uniform airflow distribution
> to all cylinders and even if you get the
> distribution perfect the
> efficiency peak is very peaky and narrow, and the
> efficiency is limited to
> 60%. My fan doesn't need any of that stuff to get
> the kind of efficiency that is expected, which
> should be 60-75%. At that kind of efficiency, the
> horsepower
> usage is less than half of what the stock fan
> uses, and if it is properly sized
> could be geared down a bunch... making the weight
> concern mostly moot even
> if it somehow ended up heavier than the stock one
> in production form.
> If it was made from a more modern grade of
> magnesium it would weigh around 30%
> less- .84 lbs, and if it can be done from a newer
> composite, it would weigh something like .5 lbs.

Has your fan been tested; real world or on a Dyno?

Lee J

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Re: Are You Driving a Bomb?
Posted by: corventure Dave ()
Date: December 13, 2017 07:36AM

Good post Ken.thumbs up

It's amazing what 50+ years can do. Also I wonder if one of these fans was possibly dropped or thrown down on dismantling starting a fracture?!?
For sure this is one more time-age related thing to check and be aware of.

A bead blast chamber is a nice thing to have. I made mine nearly 40 years ago and use it more often than one would think.

Corventure Dave



Edited 1 time(s). Last edit at 12/13/2017 07:40AM by corventure Dave.

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Re: Are You Driving a Bomb?
Posted by: American Mel ()
Date: December 13, 2017 08:39AM

Kevin, I was not trying to say that I thought that you should have done things differently.
I was merely saying that after all of this time, I am surprised that no one has tried a modern plastic alternative.

Ken, I am aware of the reaction with the Delrin fan, that is why I stated "MODERN plastics".
Surely by now we have some new synthetics that are light weight, but non-toxic when in contact with fumes from the battery.

I think that Kevin's fan is incredibly beautiful, and promises to be less of a drag at higher RPMs, but I also foresee a hefty price to it due to all of the effort put into it, to research and develop it.
While the stock fan may leave something to be desired from an engineering viewpoint, it seems to have been sufficient for our uses, since our cars are still running after 50 plus years.

.
-----------------------------------------------
WA. state, 1 mile south of the Canadian border,
I am not at the end of the world, but you can see it from here.
'66 Monza Coupe - 4spd, 140 Daily driver beater
'67 Monza Vert. - PG, 140 Daily driver beater

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Re: Are You Driving a Bomb?
Posted by: WCcorsa ()
Date: December 13, 2017 09:22AM

American Mel says "Why hasn't anyone made a new lightweight fan for our cars?"

I would guess production costs would be very high and sales very low.

Keeping in mind half if not more of the Corvairs out there running don't even use mag fans.

Also, finding good used mag fans isn't all that difficult.

In addition, countless others simply don't need a replacement fan at this point.

Top that off with the fact the number of Corvairs and parts customers is likely not getting bigger as the years tick by.

From a business prospect, it would likely be a huge risk and a big money-loser in the end.

Moreover, anyone taking that risk would have to make certain their "new" fans were designed nearly perfectly, be durable and manufacturing quality would have to be maintained throughout production.

Going to China may be the only viable financial choice, however, maintaining quality in both materials and production maybe a challenge there.

I'd love to see someone jump in and take the risk to make new fans but I doub't that will ever happen.



Edited 1 time(s). Last edit at 12/13/2017 09:23AM by WCcorsa.

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Re: Are You Driving a Bomb?
Posted by: davemotohead ()
Date: December 13, 2017 10:27AM

I knew I been driving a bomb for years and have added safety measures installed! smoking smiley





Email me at: Dave Motohead

1960 4dr sedan caveman car
1961 Rampside (Chetside)
1962 Rampside (Barnside)
1962 Short Rampside (Shortside)
1962 Monza 700 Wagon
1963 Monza 900 coup (General Nader)

-----------------------------------
Rust Free Lancaster Ca

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Re: Are You Driving a Bomb?
Posted by: Chilly Willy ()
Date: December 13, 2017 11:05AM

American Mel Wrote:
-------------------------------------------------------

>

>

> Why hasn't anyone made a new lightweight fan foe
> our cars?
>

>
> Why not a proven design(ie. the stock fan) but in
> a modern lightweight, and inexpensive
> (acid/hydrogen sulphide resistant) plastic?
>
> Would something made on a 3d printer be able to
> withstand the forces of being spun at high RPMs

I’d would improve flow efficiency before worrying about the weight.




The Corvair, Keeping Nader Notorious winking smiley


Will
Northern California



Edited 1 time(s). Last edit at 12/13/2017 11:09AM by Chilly Willy.

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Re: Are You Driving a Bomb?
Posted by: Pedigo ()
Date: December 13, 2017 11:51AM

Mine is powdercoated. I guess I'll never know unless it explodes.

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