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@cobalt Thanks for the detailed answer! I did some light brushing and it seems like its more or less still at the surface. Also tried poking it with the sharp end of the brush and its really solid, definitely not brittle. It's also not as blue in real life as on the picture, don't know why the phone camera does this, and they say the iphones are supposed be accurate
I'll clean it more and get as much of it off as possible before wiping it down with something to degrease it before applying a coating. I've read a bunch of forums and some research papers and it seems white spirit should work fine without causing damage to the case. After that, Wurth HHS 5000 seems like a good product - water resistant, acid resistant, plus it contains a small amount of teflon.
Also, you have some really cool work experience there!
I am happy it isn't more extreme. I bet you feel a lot better now knowing it isn't. The Iphone sees things our eyes can't. After spending countless hours (years) in dark rooms under UV light inspecting mag castings it is an amazing material that has so many pros and a few bad cons. Everyone complains about the cons without understanding the pros. Although I don't think Porsche was expecting these to be around still after all these years, It is important that any mag part be inspected and any corrosion addressed regularly. Fans especially. I know how hard it is to get replacement cases and I see a lot of them with this same problem that were ignore and eventually beyond repair.
Best luck, sounds like you caught it early enough.
I am happy it isn't more extreme. I bet you feel a lot better now knowing it isn't. The Iphone sees things our eyes can't. After spending countless hours (years) in dark rooms under UV light inspecting mag castings it is an amazing material that has so many pros and a few bad cons. Everyone complains about the cons without understanding the pros. Although I don't think Porsche was expecting these to be around still after all these years, It is important that any mag part be inspected and any corrosion addressed regularly. Fans especially. I know how hard it is to get replacement cases and I see a lot of them with this same problem that were ignore and eventually beyond repair.
Best luck, sounds like you caught it early enough.
I have a big corrosion problem in a 70 crankcase that i have had profesionally welded and now is heading to machining. I see you have a profound knowledge on magnesium, so I would love to know your opinion on if it could it still be used, what should I do in order to do or if it is to far gone, thanks
^^ I wish I had a simple and positive answer. I have helped some people do minor welding of their mag cases. Your's has suffered extensive corrosion and cracking. If this was an aircraft part it would be scrapped.
The issue with welding a mag case is multi faceted. What did the welder do to prep the surface? What filler rod did he use? Did he grind most of the old material down prior to welding including chamfering the crack? Did he heat the case or area welded to at least 500 degrees F before? Normally after welding a part it would be heat treated. After welding the temper is gone. Heat treatment is done prior to any machine work. Keeping the case from warping while processing is difficult but not impossible. However you will be hard pressed to find someone to run a solution cycle, quench and artificial age which is a three step 24 hr plus process specific to mag. Most heat treatment facilities won't touch mag, that is why I processed them myself.
My bigger concern is I am seeing signs of extensive corrosion, scabbing and other stress risers that could become an issue in other parts of the case. There appears to be a minor crack in the weld for the large crack. 7th and 8th picture. It is a chance using this but if you are left with 0 options it might work but for how long is hard to say. I guess now is the time to consider alternative options prior to the matching operation.
I am curious was this case sitting in a moist environment for a long period unassembled or was the oil full of water and sat for along time? It looks like the openings for the jugs are corroded as well?
Personally unless it is matching numbers I would search for another case. The odds are 50/50 it will not become an issue again. It all depends on what they are charging to do the machining and if it is waste of money or not won't be known until it is done and assembled.
wow. we should wait for @cobalt to share an opinion. That's pretty far gone though, is this the original case? I hope you can save it, unless this is a historically significant car I'd probably have saved off the case with the car and found a replacement to run the car.
There are many areas I can point out that may or may not be a concern.
The upper circle shows what might be a crack in the weld. The lower circle shows scabbing. This might be minor or covering something major. I would take a pick and poke at the area. More than likely material will flake off. How much is the ?. It is what is underneath you need to inspect. This could be nothing or a stress riser that could cause that boss to eventually fail. All depends on the stress level it sees. There are other areas like this as well I would investigate before taking a chance.
03-26-2024, 09:06 AM
