Re: Welding Aluminum and Steel - Exhaust Manifold Question

["David R. Lefebvre" <drl@xxxxxxxxxxxxxxxxx>]

It was off a 96 328IS.

You were right about the aluminum. I talked to my boss the other day and he 
said they probably used a filler on the crack in the aluminum pan. He 
agreed there is no way to mate aluminum and steel alloys. He used to 
rebuild a lot of motorcycles. We are ChE's.

BTW- I don't know if BMW has a similar part, but Mercedes makes a 
protective, bolt-in plate to cover the oil pan.

Perhaps the mechanic mistook the materials as you mentioned. I'll ask him 
if he kept it.

At 05:47 PM 3/18/03 -0500, you wrote:
>David,
>
>   Sure certain alloys of aluminum could be welded back in the mid 80's, but
>there are even more weld able alloys of aluminum now.  BUT you where
>talking about aluminum to aluminum, actually filling a crack or hole with a
>fillet of aluminum rod.
>
>   Unless there is something I have missed in my 38 years of working
>directly in the automotive field, I have never run into an aluminum exhaust
>manifold.  What did this come off of?  What year is it?  Even with the
>added special frequency generators added to a mig machine to weld aluminum,
>there is no wire that I know of that can be used to weld aluminum and steel
>together, nor would there be any electrode and rod that I know of that
>could be used for tig.  And certainly the exhaust manifold and/or the
>bracket is not made of cast iron.  People mistake cast steel for cast iron.
>Not all steel parts are formed or machined from "blocks" of steel.  Cast
>iron was and still is used for pipes like water mains, fire plugs etc.
>Exhaust manifolds are generally cast steel.  I would suspect that if you
>put a magnet to this manifold it would stick.  I would be curious to hear
>if a magnetic does stick and off of what car and year this manifold came
>from.
>
>   At any rate, it sounds like you've found a replacement for a reasonable
>price.
>
>Happy motoring,
>
>tom

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