At 05:25 PM 04/01/2006, you wrote:

>Date:    Wed, 4 Jan 2006 17:25:28 -0800
>From:    David Shepherdson <shepherdsond@METRO.DST.OR.US>
>
>Thanks to all that gave me feedback on this problem. One suggestion was
>excessive crankcase pressure, I am pretty sure that the breather hose
>(to the intake boot) is OK but will certainly double check (and try
>putting my hand over the oil filler pipe when I get it running to see if
>I can feel it).

Excessive pressure can cause the oil to go by, 
but as John Rodgers wrote, it is unlikely to damage the seal very quickly.

snip

>By the way Ratjen asks what I mean by
>catastrophic failure?  I mean that all the oil drains out in a couple of
>seconds while the engine is running and of course the oil warning buzzer
>comes on. This is caused by actual damage to the seal (the sealing lip
>which contacts the flywheel was torn the first time and the face of the
>seal that faces the flywheel had a small crack in it the second time).
>I can't be sure that this is what happened the times before I bought it,
>it could be just that the seal was dripping oil. Judging by the speed at
>which the oil came out this time I am pretty sure that the seal is
>damaged again for the third time, it will be interesting to see where.
>Could this kind of seal damage occur as a result of crank or flywheel
>wobble or case mis-alignment(I can see how that might cause leaks but it
>is not so obvious why that would damage the seal). I can also rule out
>pilot bearing as I changed this last time it happened.

Catastrophic failure means that a part or several 
parts basically disintegrate. This can make it 
difficult to analyze the cause. If your oil is 
coming out that fast ("seconds") then there is 
another issue. Your engine contains 4 liters of 
oil. How long does it take to pour 4 litres into 
the engine at full stream from a container?
The crankshaft seal basically keeps the oil that 
is spun by the crankshaft from flowing any 
further. Even if you would leave the seal out it 
would take a while (minutes) to dump all the oil 
from the engine. If you lose oil that quickly 
("seconds") then there must be another leak. If 
there is damage to the seal then the location and 
direction of the damage can tell the story of the 
injury (overstretching, contact with sharp object, etc.)

The pilot bearing is important for the integrity 
of transmission seal to avoid wobble of the transmission shaft.

snip

>Thanks,
>David
>

Bj�rn

Bj�rn Ratjen, Ph.D.
Cobble Hill, B.C.
phone/fax (250) 743-7575