My comments on sumps was more in reference to issues i know of with alfas,
but i am aware of the pitting on porsche motors.. long and the short of it,
amgnesium wheels are very light and great when new.. they were used for
racing as they are seen as consumables.. they are not a good long term
option on ars.. new wheels might be better but any of the wheels from the
60-70's there wil be issues.
On 20 May 2010 10:33, Would U.Believe <mcdangerous@verizon.net> wrote:
> Michael,
>
> The Porsche 911 air cooled engine was a dry sump engine; the whole case was
> made of magnesium. In all my experience with Porsche, over many years, I
> have never, ever heard of an engine case rotting or breaking randomly.
> Certainly, though, magnesium has a much greater tendency to fracture
before
> some other metals and alloys, but it would take some doing to get that to
> happen even to a 40 year old magnesium engine case. Having said that, I
> know the Porsche magnesium engine cases can definitely corrode and become
> pitted badly, but only when completely neglected with water sitting on or
in
> them for a very long time. The reason Porsche eventually moved to aluminum
> engine cases was only because the magnesium cases, which started out with a
> 2 liter displacement tended to warp increasingly more (and leak oil) as
the
> engine displacements grew from 2.2, 2.4 to 2.7 liters, increasing the
> engines heat generation with each step up. I would never have guessed it,
> but aluminum cases are stiffer than the magnesium cases.
>
> Anyway -- back to wheels -- could it be that real magnesium wheels were a
> bit porous to begin with, even when new, which is part of the reason why
the
> old mag wheels needed tubes in the day (beyond the bead design)?
>
>
> On 5/19/10 7:52 PM, "michael king" <michael.s.king@gmail.com> wrote:
>
>
>
> On 20 May 2010 08:24, Would U.Believe <mcdangerous@verizon.net> wrote:
>
> There are going to be a whole lot of Porsche 911 engines disintegrating if
> that's the case. They were magnesium until the 3.0 liter engine came out
> in
> somewhere around 1980. This is the first I've heard about magnesium
> "rotting".
>
>
> Mauro
>
> Magnesium wheels are well known for turning porus "rotting" they become
> very brittle and fracture. As for other magnesium parts.. its not an
uncomon
> issue on magnesium sumps.
>
>
>
--
Regards
Michael King
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