Date:         Sat, 5 Feb 2000 12:38:54 -0800
Reply-To:     David Beierl <dbeierl@IBM.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@IBM.NET>
Subject:      Re: Hydraulic valve lifter (mis)operation

There's a distinction to be made here -- I've been trying to make it but
apparently not clearly enough.  The specified and proper and normal and
correct and standard and usual procedure is to start with fully extended
lifters (which is how they are when you install them), adjust them to
touching and then two full turns beyond, secure them, and forget about them
until the next rebuild.

UNFORTUNATELY that doesn't always work.  There is a defect in the system
(in some cases) that is allowing the lifters (in some cases) to overextend
by a tiny amount which makes the valves leak.  THIS IS NOT NORMAL
OPERATION, BUT IT EXISTS.  When it DOES exist, the "temporary" workaround
cure has been to reduce the preload adjustment from two turns to one turn,
or half a turn, or a quarter turn, or none at all.  In the case of the
engine that I'm driving around,  it is absolutely intolerant of any
preload.  When I adjust by the method of backing off until the compression
stops rising, I end up with about .006 lash.

I am trying to discover the source of the problem.  I have theories about
it, not yet tested.  I invite ANYONE to discover and PROVE the source of
this problem so that we can all go back to adjusting these things the
proper way, which is two turns preload immediately upon installation.  That
gives the proper distance so that the lifter can compensate properly in
either direction.  There should be no need whatsoever to let the lifters
"pump up" since they are installed fully extended and already full of oil.

ANY PERCEIVED NECESSITY TO REDUCE THE PRELOAD FROM TWO TURNS IS WARNING
THAT THE PROBLEM EXISTS -- REDUCING THE PRELOAD (WHICH REDUCES THE SPRING
TENSION IN THE LIFTER AT THE SAME TIME THAT IT REDUCES THE AVAILABLE
ADJUSTMENT RANGE) IS A **WORKAROUND** AND NOT A CURE.

<flame off>

david

At 07:03 AM 2/1/2000 -0800, Richard Bias wrote:
>All,
>  The whole thing about adjusting to 6 mils of lash was and is only a
>momentary (1/2 hour tops I believe) part of the "adjusting process".  No one
>said (and if they did, they were wrong) to leave the valves at 6 mils of
>lash.  It is just to get the lifters to pump full of oil before you adjust
>them back down 1 turn (360 degrees) from 6 mils, to allow the "hydraulic"
>part of "hydraulic lifters" to take over from there.
>  Rich

David Beierl - Providence, RI
  http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"