Aluminum or magnesium

[preaction]

Is there a way to tell apart an aluminum valve cover and an magnesium cover other than guessing at the color ?

[machoneman]

Vinegar, believe it or not.   

https://www.youtube.com/watch?v=g2A5o_MJ1-k

[gdaddy01]

that was cool . does the vinegar harm the magnesium , can you clean with it ?  more questions .

[preaction]

Great info thanks.

[GJCAT427]

I`ve always found that mag is lighter but it takes a real feel to tell. This comes from years of working with both materials. You can tell also by the grinding test. The sparks on mag will come off as little sparks.

[machoneman]

that was cool . does the vinegar harm the magnesium , can you clean with it ?  more questions .

Yes, if the magnesium part is grease, oil and paint free, vinegar is a great cleaner.

[BattlestarGalactic]

They weld basically the same, but with different results.
I had a couple damaged holes on my Doug Nash case.  I "assumed" it was aluminum and had friend at work weld it with alum rod.  Did fine.  That is until I tried to machine it.  The area welded basically fell out as soon as I plunged a tool into it.  The whole puddle/delusion area, thus even a large area needed welded.  I was confused, til we realized what was wrong.  I purchased some mag rod and rewelded it.  Worked perfect.

The case still had the shift rods in it, so it was feeling heavier then if it was just the empty mag case.  Lesson learned.  Didn't know about the vinegar trick.

[GJCAT427]

Larry, that is one trick I learned about welding aluminum vs Mag. I did a lot of Lawn boy decks many yrs ago and got fooled when a weld fell off when it cooled. Seems lawn boy cast some alum decks. Imagine my surprise to see the mag rod fall off the deck. I used my old fail safe test to see what the deck was. Ground some of the deck  and swept the powder up set it on a steel plate and tried to lightit. It wouldn't burn. Mag powder will light with a bang. thus the deck proved to be alum and I did weld it up with the right filler.

[jayb]

I've checked SOHC valve covers using the vinegar trick.  Works great.

[Heo]

A warning to all of you.  A guy i know was building some kind
of bracket for a motorcycle out of some "aluminium" he had
laying around. I think it was cut from a VW transcase
He did a lot of grinding on it on the bench grinder
and had the coveralls covered with the grinding dust.
Then he started to cut some steel with the angelgrinder.  BOFF
and he was on fire. The bracket was magnesium and the sparks from
the steel cutting set the magnesium dust on fire.
Lucky for him he had a lot of clothes under the coveralls so
he suffered  just minor burns

[gdaddy01]

I have read in the past that old timers would set fire to vw engine cases at Bonneville salt flats , may  be just a tail , but I always wanted to go .

[BH107]

I have read in the past that old timers would set fire to vw engine cases at Bonneville salt flats , may  be just a tail , but I always wanted to go .

We used to do it at the sand dunes... quite the camp fire but made it easy to find camp after a night ride. Then one year my dad got ticketed for it and that was enough.