Date:         Sun, 21 Apr 2002 21:49:04 -0500
Reply-To:     Stan Wilder <wilden1@JUNO.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Stan Wilder <wilden1@JUNO.COM>
Subject:      Re: Strange clacking (valve Lifter?) noise.
Content-Type: text/plain; charset=us-ascii

To anyone that has read the post duplicated below.
The findings below are what I found out.
The opinions are mine.
They may be contrary to what others have told you.
I'm one of those that advocate the use of Marvel Mystery oil however
these are the results you can get with old marginal engines. a) Cleans
the crankcase walls, oil ports, piston insides and anything it touches
inside the crankcase. If your lifters are full of crud and the Mystery
Oil cleans it out then they should work smoother but if the crud is
supporting the required pressure it can reduce the operating pressure. It
can cause your case to leak if crud has been sealing minor imperfections
in the sealing surfaces.
b) When run as a fuel additive: Cleans your valves, guides, piston tops,
ring groves, combustion chambers, fuel lines, fuel injectors. If your
rings are supported by carbon and buildup of crud the engine may loose
some compression (it normally comes back as the rings reseat themselves)
I use Marvel Mystery oil for about 300 miles before each oil change to
remove in process buildup.
Others use it as a one quart suppliment for oil when they change their
oil and they get good results using it this way.
c) On newer low mileage engines it just cleans the parts before buildup
begins.

-----Copy of Original Post ------------------------------
Since I had a slow Sunday I pulled my spare 2000cc Air Cooled Type IV
engine out and started disassembly for the purpose of installing a
windage tray and other modifications.
I didn't get far before I got misdirected into investigating the action
of hydraulic lifters.
Taking the eight lifters out of the spare engine I set up a metal can
full of oil and carefully blead each one with a wire pin while it was
fully submerged in oil. (I disassembled an old, known to be bad lifter to
be sure that I could bleed them properly).
I then re-pumped each one with my little lever action press with the
lifters still submerged completely. (hand operated gear / rack, lever
operated press).
I had the eight lifters out of the good operating engine and each of them
pumped up to become solid columns with just a few pumps of the press.
I had counted on mounting a dial gauge on the head stock to measure
compression / drop of each lifter as pressure was applied.
All but one of the lifters became very solid and held the applied force
so I skipped the dial gauge setup.
The force being applied was equal to about 200 + pounds and seven of the
lifters showed no signs of compression after about one minute. The eighth
lifter developed about 3/32" drop after one minute but recovered after I
actuated a few pumps of the press. However it dropped again in about one
more minute of press action.
I set these aside and tested four of a eight set spare lifter set.
Only three of these four held pressure and became a solid column. The
lifter that did not hold its column height seemed destined for the trash
can since it quickly dropped as much as 1/4" on repeated testing.
What I learned.
If you've got a new lifter set they will most likely be good and could be
set with zero preloading.
If you're got an old lifter set they may perform better with a preload of
one to two turns of the adjusting screw.
If you're going to rebuild your own engine, you should probably test your
old lifters if you're going to use them again.
If the PO ran the engine with dirty oil the lifters could be past ever
holding a column.
Each full turn on the adjusters is approximately .050 inch (varies
slightly depending on the thread fit of the adjusters).
I didn't have a quality method to measure the exact pressures applied but
it would be interesting to see a more comprehensive test of time and
pressure.

Stan Wilder
83 Air Cooled Westfalia

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