Date:         Wed, 27 Jun 2007 23:23:11 -0700
Reply-To:     David Kao <dtkao0205@YAHOO.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Kao <dtkao0205@YAHOO.COM>
Subject:      Re: Hydraulic Lifter Adjustments
In-Reply-To:  <46832FCE.4040006@gmail.com>
Content-Type: text/plain; charset=iso-8859-1

In my opinion, because hydraulic lifters self adjust it really doesn't
matter the adjustment 1s 1 or 2 turns. Anywhere 1 to 2-1/2 turn should be
fine. I know, some of you guys will beat me up on this. Please read on
before you do that.

This is how I look at how hydraulic lifter works. Engine oil inside a lifter
is not compressable. If the pluger is too high it can only be lowered by
compressing the plunger to force some oil to leak out. This compression
force comes from the valve spring. If the pluger is too low oil will be
pumped into the lifter body. So lifter pumping by the cam lobe and oil
leaking because of compression from the valve spring will adjust the pluger
position to a height that the valve will seat on the valve seat and there
will be no clearance between valve tip and the rocker.

Valve springs are far stronger than the little springs inside the lifter
beneath the plunger. So no matter how many turns the adjustment screw are
turned the lifter plunger will always yield to the valve spring pressure
to settlle at a proper height to allow valves to seat on the valve seats
properly.

For a valve to fail to seat the lifter has to be stuck. It is unlikely
a lifter will not yield to the strong valve springs. Once the engine is
started the lifters will self adjust within a couple of minutes. Some
lifters will be pumped up and some will be compressed down. Older lifters
will self adjust faster than new lifters. Lighter oil weight also makes
the self adjustment time shorter.

So the lifter adjustment between 1 to 2-1/2 turn really doesn't matter.
It won't make any difference to engine performance. I would make at least
1-1/2 turn so the lifter has plenty of room for self adjustment in either
direction. There is really no need to worry that improper adjustment of the
lifters may lead to burnt valves or poor performance, unless you have stuck
lifters which is very unlikely.

David



--- vanagonvw <vanagonvw@GMAIL.COM> wrote:

> 81, air cooled. Hydraulic lifters
>
> Damn, it is really hot here in Northern Utah... Sweating like a madman
> in the garage, and under the van.
>
> I am thinking this topic gets bandied about almost as much as tires :-)
> I have read the archives, and other forums. Still want to better
> understand some things tho....
>
> How I got here may not matter at this point, but I am doing a leak test
> on my 81 air cooled. The motor is cold. Last driven a few days
> ago...Having a horrible time getting exact TDC. Off by a few degrees,
> and the air pressure just pushes the piston down, and the motor around,
> in  whichever direction. :-)
>
> To get started, I took the easy way, and went with number one. Used the
> timing marks, and  only needed a few tries to get the piston to stay up,
> and do the test. It failed, with 90psi in, and about 50psi reading, or
> 45% leakage. In order to see what was going on with the valves, I took
> off the cover, and noted that with the piston certainly at TDC, the
> intake valve had a small amount of 'play' or 'lash' between the rocker
> arm, and the stem.... The exhaust valve, however was leaking a lot,
> based on what was coming out the tailpipe, relative to the intake, and
> it had no play or lash at the stem. So, I backed the adjuster screw out,
> eventually two full turns, resulting in a small amount of play, and
> apparently this allowed the valve to close completely, and the leakage
> went down to just 20%, which is not all that bad for an engine with 200K
> miles on it. I would take that if they were all at 20%.
>
> What did I learn, and how come I am supposed to set zero lash, at TDC,
> and then one to two turns down, depending on which article I read?  I
> don't understand the notion of adjusting that rocker arm,  so that it
> actually opens the valve at a point when it is supposed to be
> closed..... When the lifter pumps up, won't that make it even worse? Is
> that indicative of a bad lifter? Weak springs? Wrong interpretation of
> the procedure <g>
>
> I would really like to  understand how to set it up properly.
>
> (section two)
>
> It may be a totally moot point however, as number two, after an hour of
> trying to find TDC that would not push the piston down, I found almost a
> 50% leakage, mostly exhaust if I am any judge, and both valves had a
> small amout of clearance. They were not open at all, based on the
> ability to pull the rocker arm back off the stem, on both of them. Not a
> lot, but enough to know, I have a problem....
>
> My only choice is to get the remaining cyls tested, adjust the valves as
> best as I can, and park the van, indefinitely, but I need it as a spare
> set of wheels. My Ford Taurus trans went out today, so without the Van,
> I have nothing to drive, and I at least need something in case of an
> emergency for my kids, or hell, even me :-) No intention of driving it,
> unless I absolutely have to, as that could make things ugly if its a
> seat that has dropped a bit, but I cannot afford a new trans for the
> Ford, let alone a new set of heads for the van, so I want to set the
> valves up as best as I can. Plus, good practice, in case I ever get to
> be able to fix this.
>
> Anyway, I hope things maybe look  somewhere in the future, but for now,
> I want to do the best I can with what I have, so any education from the
> resident experts, would be appreciated. Kind of two issues here, but I
> want to learn what it is, that I am seeing on both cylinders...
>
> Thanks very much,
>
> John
>
>
> P.S. Would I want to try and take that head off, with the engine still
> in the car, and more important, if yes, is it an overwhelming bitch to
> do? Probably another thread, once I get it all tested, and adjusted as
> best I can....
>




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