Date: Sun, 27 Feb 2000 18:00:32 -0600
Reply-To: John Rodgers <inua@HIWAAY.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: John Rodgers <inua@HIWAAY.NET>
Subject: Re: CRACKED BLOCK 2.1-- Expert Opinions??
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When I used to do aircraft engine work crankcases, cast in two halves just like WBX
cases, would have cracks in them just about anyplace. There seemed at times to be no
rhyme or reason. They would just crack. Ocassionally it would be due to something
specific, like overtorqueing a case nut or a through bolt. But much of the time it
would turn out to be fatigue cracking occuring over the life of the engine due to
exposure to continuous vibration .
It's hard to tell the difference at time.
Unfortunately, with one exception, welding of the case never prevented failure in the
future, often at the most inoportune times.
Of course yours is not an aircraft engine, so perhaps in the hands of the right
fellow, the case may be welded successfully, and the life of the case extended. But I
wouldn't bet the farm on it.
Good luck,
John Rodgers
"Horace K. Sawyer" wrote:
> >Good luck, and that is definitely a weird one! That area is not subject
> >to any particular stress, so it is hard to guess why it cracked.
>
> Hmmmm . . . sounds like defective manufacture. Defective metals,
> defective casting, defective moulding, defective pouring process, or
> something. Wonder if someone could produce some expert opinion evidence to
> back this up. In a non-stress area of the block, seems to speak for itself
> that something else was wrong with it that had little or nothing to do with
> the operation of the engine or maintenance, etc. A block should be in
> service "for life" and guaranteed against cracking in a non-wear zone as
> long as it has not been overheated or subjected to improper maintenance.
> Am I right here?
> It would be very interesting to glean the factory production line records
> of this particular run of engine blocks. The same operator may have had a
> bunch of rejects, or his blocks may have had the same problems. Or it
> could have been a bad batch of metals on that production run? There has to
> be a "right" way and a "wrong" way to make a block. It it's not RIGHT,
> then its wrong. Something in between those two could cause problems down
> the line. Example: block was cooled improperly after casting, or had an
> air pocket in the molten metal or similar? Or what else, experts?
>
> HK
>
> Still questioning authority.
> Still stirring up trouble from his comfortable easy chair
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