Date:         Fri, 9 Feb 2001 19:41:27 -0500
Reply-To:     Dennis Haynes <dhaynes@OPTONLINE.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Dennis Haynes <dhaynes@OPTONLINE.NET>
Subject:      Re: Oil pressure light on at idle: add a $1.50 oil booster spring.
In-Reply-To:  <8a.22d5f73.27b59dfb@aol.com>
Content-type: multipart/alternative;

A different spring will do nothing at idle with a hot engine. The oil
pressure is really a function of how much volume the pump can flow/and oil
flow allowed. A gear type pump is a positive displacement type pump. If
there is no flow at all, then either the pump has to stop turning or
something has to burst to relieve the pressure. If there is no restriction
to flow, then there is 0 pressure. Since cold oil does not flow easily, the
relief valve is there so that excess pressure can be relieved. When the
pressure overcomes the spring pressure, the valve will lower allowing oil
flow through the relief port. This ensure adequate flow. I've seen attempts
at modifying the spring and using a rod to hold the plunger up all the way.
The rod resulted in shearing the tang off the oil pump shaft. If the engine
is loaded with gook, it is possible that the plunger is not seating fully
causing the valve to always leak. This will cause low pressure problems at
idle. So will a worn pump.

Dennis
  -----Original Message-----
  From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com]On Behalf Of
Robert Lilley
  Sent: Friday, February 09, 2001 2:25 PM
  To: vanagon@GERRY.VANAGON.COM
  Subject: Oil pressure light on at idle: add a $1.50 oil boster spring.


  The oil on light at idle, is a common problem in T1 engines.  An oil
booster
  spring has been used to boost the oil pressure back up to what is needed
to
  get more life out of the engine.

  The stock pump puts out 150 to 200 psi.  The stock spring is set to
relieve
  this pressure and allow only @10 psi per 1000 rpms or about 40 psi at 4000
  rpms (the ACTUAL psi might vary according to VW specs, I do not have them
in
  front of me).


  Adding the booster spring helps to make up for the increased clearances
due
  to worn bearings.  I do not recommend using the spring as a substitute for
a
  rebuild, but to get some more life out of the engine as you PREPARE for a
  rebuild in the future.
  I would also not drive push the engine hard.

  Bug Pack, Empi and several other makers have them.  They are for a T1
engine,
  but should work in a WBX engine.  The spring is about an inch longer than
a
  stock spring.  I will be putting one in an engine that I have been working
on
  for a friend in the next few days.

  **I would ADD an oil pressure gauge to keep a check on the pressure during
  running, so IF the pressure drops (with the spring) you can save the
engine.


  My friends pressure, when hot drops to 23 psi at @3500 rpms.  He has new
rod
  bearings (his old were worn out) We did a top end rebuild, but did not
crack
  the case so I suspect that the mains are worn and this is where the
pressure
  is lost.  I will report back on the results of the pressure increase
later.

  **The use of a counterweighted crank eliminates this bearing wear because
the
  harmonic vibrations that cause the wear are neutralized.  The crank,
because
  it has two center offset journals, wants to FLEX in the center.  Adding
  counterweights eliminates the crank flexing and the bearing wear.

  *This is one, if not the most important, modification I made to improving
the
  life of my engine.

  Robert

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