Date: Wed, 15 Sep 2004 23:01:06 -0400
Reply-To: Dennis Haynes <dhaynes@OPTONLINE.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <dhaynes@OPTONLINE.NET>
Subject: Re: Noisy lifter update
In-Reply-To: <EEEJIEJFIKFOCCBNCFHCMECECDAA.wilden1-1@sbcglobal.net>
Content-type: text/plain; charset=us-ascii
The lifter bores are actually pressure feed from the same galleys that
feed the cam bearings. The holes on the side of the lifters are actually
the lifter oil inlet. The oil enters the lifter and then some of it
passes through the socket to go through the push rod and then lubricate
the rockers and to a small extent the valve stems.
The socket sits on top of a piston assembly which is feed underneath
through a spring loaded check valve. Oil goes in, but shouldn't come
out. Some oil will bleed through the side of the piston. This is also
how the lifter loosens as needed.
The design problem here is that there is no easy way for the air to exit
if the cylinder area becomes air bound. All hydraulic lifters are
designed to bleed down. The bleed down is designed around oil pressure
and rpm requirements. Excessive oil pressure and/or high rpms can cause
the lifter to actually overcome the valve spring and cause it too float.
You see this effect when properly adjusting a lifter that is not air
bound. As you tighten the rocker past touching, you will actually see
the valve get pushed open. This is why after adjusting valves; you need
to wait a while for the lifters to bleed down a bit so the engine will
start.
Shortly after starting the engine, and the oil galleys fill, oil should
flow past the ball check and fill the lifter to stop the clacking. At
this point, oil pressure is actually lifting the valves.
Lifters that clack for extended periods usually do so because they are
not filling with oil. This can be caused by clogged galleys,
insufficient oil pressure, sticking ball check, or what is usually the
case with the Vanagon, the air pressure in the lifter is enough to
prevent it from filling with oil. If we let the engine warm up, the
outside of the lifter will expand with heat allowing additional
clearance between the bore and lifter piston. This will allow the air to
bleed out and the oil to enter. This is why the usual fix is to let it
warm up and then drive.
Adjusting the valves to have some lash (slop) does not help anything. At
best, when the engine is shut down, only three valves will be fully
closed, (no lifter pressure), and one would have to aim for this. The
remaining lifters will still be forced to bleed down slightly. It also
defeats some of the purpose of hydraulic lifters.
If you have a lifter that regularly causes grief, you probably have a
bad lifter. If miracle stuff in a can really helps, then you have a gunk
up engine with other problems to follow. The choice of filter really
does not make a difference.
For some reason, it seems the lifter problem is also caused by short
cycling the engine. Starting the engine to move a van around the yard a
few times seems to bring on this symptom. Again allowing the engine to
warm up and then drive it usually corrects the problem.
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
Of Stan Wilder
Sent: Wednesday, September 15, 2004 9:41 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Noisy lifter update
I don't know why anybody is surprised when they have lifter noise.
The lifters have a hole in the side that allows oil to escape to
lubricate
the lifter bores.
These holes will leak no matter where they stop in their rotation
process.
It just takes a minute or two to get the lifters refilled with oil.
I think Bob Donald's lifter setting is good because when the engine
stops
the lifter isn't under load and the oil in it isn't under pre-load
pressure.
In this benign state the oil isn't pressed out of the lifter as it is
with
one or two turns down as pre load.
Stan Wilder
More Power with Performance Coatings
http://www.engineceramics.com
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com]On Behalf
Of
Darryl Carpenter
Sent: Wednesday, September 15, 2004 7:38 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Noisy lifter update
Listees
Thanks so much to those who came to my rescue with their solution. Many
were repeats of the same info (thats good..consistant info!) and some
were unique.
I offer a different perspective from a writer from the website
westfalia.org. I present it only as a different look at the problem I
asked about.
Thanks again
Darryl
"Synthetic oil has nothing to do with lifter bleed-down. If anything, it
may contribute to it since most synthetics are a slightly lighter base
weight.
Additives that increase viscosity can reduce bleed-down, but they come
with the same undesireable side-effects of changing viscosity to one too
heavy for the intended use.
Proper oil and changes have more than enough detergents and anti-gumming
additives. There are no magic mechanics in a bottle -- every additive
has plus & minuses. VW cautions they are not needed or desireable.
Proper viscosity is the most important characteristic -- the thinner the
base, the more likely to bleed down, so a 10W30 is more likely to
experience lifter bleed-down than say a 15W-40, one of the best
viscosity choices for the Vanagon in most locales.
That you have bleed down after a 2-week idle period is not unusual, and
in fact, expected. It can occur in very new cars. It, in itself, is not
a sign of pending hydrualic lifter failure. Did it pump back up after a
few miles with the engine warm and stay pumped up over idle periods of a
few days? If it did, you don't have a problem.
There are a number of 'engine flushes' on the market. Most are a waste.
The modern premium oils have such a high level of detergent, they
perform much the same effect. In fact, if the engine has been abused by
infrequent oil changes, too strong & sudden a flush might break some
deposit loose that blocks an oil passage.
The recommendation for a factory OE or OEM filter is also discussed with
the oil topics. Besides quality, you are seeking the correct
high-pressure relief valve in the filter to prevent engine damage in
case of an obstruction. Cheap aftermarket filters may not have correct
relief settings, if they even have the valve at all. Mahle (bought out
Knecht) and Mann are good OEM brands. Mann (German company) has a plant
in the US and was VW's supplier for the N. American market, if not
still."
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