[Vwdiesel] Oil Pressure Testing on an '84 Bunny

Chris Geiser cfgmail at hughes.net
Mon Oct 16 22:23:36 EDT 2006


Didn't think of it, but I had the same symptoms as you and it ended up being
the pressure sensor on the oil filter housing.  This was in the late 80's,
so took me a while to remember that...

Anyway - I think you've probably got it figured out.  Scares the s**t out of
you the first time it happens though!!



-----Original Message-----
From: vwdiesel-bounces at vwfans.com [mailto:vwdiesel-bounces at vwfans.com] On
Behalf Of Bryan K Walton
Sent: Monday, October 16, 2006 1:01 PM
To: LBaird119 at aol.com
Cc: vwdiesel at vwfans.com
Subject: Re: [Vwdiesel] Oil Pressure Testing on an '84 Bunny

On Sat, Oct 14, 2006 at 11:04:43AM -0400, LBaird119 at aol.com wrote:
> In a message dated 10/13/2006 7:51:41 AM Pacific Daylight Time, 
> bryankwalton at machlink.com writes:
> > Now, here is my final question: with my warmed up car idling and my
> > oil pressure at 20psi, my oil pressure idiot light was still coming
> > on.  Can I infer that my oil pressure switch located at my oil filter
> > is probably faulty and should be replaced?
> > 
>   Idle pressure is the one on the end of the head.  It shouldn't 
> work the idiot light until around 4psi.  I'd replace that one.  The 
> one on the filter is for above 2K rpm
>      Loren

Hi Loren,
	Thanks for the reply.  I agree, idle pressure is suppossed to
be handled by the switch at the cylinder head.  However, in my testing
this weekend, here is what I found:

1. I disconnected the wire from the switch in the cylinder head.  I
can ground it and also shield it from being grounded, and it makes no
difference -- once the oil gets up to temp, the light comes on at idle.

2. This is where it gets really odd. If I disconnect the wire from the
switch on the oil filter flange, the warning light comes on,
even with the engine oil cold (and the wire NOT grounded). Note, with this
wire disconnected, the light comes on and STAYS on, doesn't matter if the
oil is hot or cold and doesn't matter whether the car is idling or going
65mph down the freeway.  Now, if I ground this wire to the body, the light
NEVER comes on. 

I'm going on the assumption that the sender located on the oil filter
flange is either faulty, or at least not the correct sender for my
bunny.  In the scenario above (when I was driving down the road with
the wire disconnected from the oil filter flange BUT NOT grounded) the
idiot light was always lit up, regardless of RPMs, but the warning
buzzer never sounded.  Perhaps I also have a faulty relay, but for
now, I'm going to point blame at the high pressure sender on the oil
filter flange.  If anybody thinks my assessment is wrong, please let
me know.

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