Wow, that's an odd one.  I have to contribute my 2 cents worth on this just for fun.  I'll bet the old pushrod tubes are the problem, not the seals.  They may get less malleable as they  age, and after stretching them for reuse they may not have the flexibility they once had, and that leads to too much pressure on the seals.

I assume you'll replace these tubes with spring loaded ones, and I doubt you will have any problems with them.  You may want to replace the pushrod tubes with new ones on all your rebuilds now.

Stuart

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of kenneth wilford (Van-Again)
Sent: Wednesday, June 22, 2016 9:03 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Problem with push rod tube seals?

So I have been using the Victor Reinz and or the Erling complete engine set
for years and years to on rebuild engines and cylinder head jobs.  We have
done so many over the years with no real issues.  However the last two
engines we rebuilt started having problems with oil leaks from the push rod
tube area not long after we rebuilt the engine (probably 2000 miles
range).  I just had one of the customers in here this morning and it seems
like an issue with the push rod tube seal itself.  The small end ones
seemed to be expanding and trying to squish out around where they seal to
the interior of the engine under the valve cover.  One was so bad that it
cut in half and the other two on the opposite side of the engine were just
starting to emerge and do the same kind of thing.  Not all of the seals
were doing this, the large end seals which are made of the same material
were fine and most of the other small seals seemed to be fine.  Anyone else
have a similar issue lately?  I am just wondering if it is an isolated
problem or something I should call my supplier about?  I think the kits we
have used lately have all been the Victor Reinz ones if that helps out.

--
Thanks,
Ken Wilford
John 3:16
www.vanagain.com