Date: Fri, 23 Feb 2007 08:50:12 -0800
Reply-To: David Marshall <mailinglist@FASTFORWARD.CA>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Marshall <mailinglist@FASTFORWARD.CA>
Subject: Re: Problem: Oil pressure light/buzzer at over 2KRPM. Help!
In-Reply-To: <23258.1656.qm@web84204.mail.re3.yahoo.com>
Content-Type: text/plain; charset="iso-8859-1"
I think from about 1986 and on, all VWs have what is call the
"dynamic oil pressure warning system". So most engines
after this time have two oil pressure senders. Usually
one is 0.3 bar (blue/black wire) and the other is 1.8 bar (yellow wire) -
these pressure values are different for different engines, but essentially
one is a low pressure and one is high pressure.
At speeds below
2000 rpm the system reads only the lower pressure sender, if it is not
over "X" pressure then the alarm goes off. If pressure is
achieved the sensor closes and the wire from the engine will be shorted to
ground. Above 1800 to 2000 rpm the system will then start reading
the second pressure sender, because at this engine speed you should be
developing more pressure, again if this sensor sees above "Y"
pressure, it goes to ground.
So if you rev the engine >2000
rpm and the oil warning system goes off, then it is one of three
things. A fault pressure switch or the wiring related to that (the
yellow wire), faulty pressure circuit, which is located in your
speedometer, or your engine is actually not making enough oil pressure and
you do indeed have a problem.
David Marshall
http://www.hasenwerk.ca
http://www.fastforward.ca
Box
4153, Quesnel BC, Canada V2J 3J2
On Fri, February 23, 2007
08:21, WARREN WOODS wrote:
> I hope someone's been through this
before and can help me. My '91 Vanagon
> Carat std shift with
155K miles runs fine and the engine seems very tight
> (no ticks
or raps). I bought it new and have never run it over 65mph -
>
have replaced the heads twice, tho.
>
> Problem is that
the oil pressure light and buzzer come on at engine
> speeds over
2krpm and won't go off when speeds drop unless I turn off
> the
ignition - then all is quiet until I run over 2krpm again which is
> hard to avoid when going up through the gears. The car will run
all day
> at the lower speed. Some years ago I had the
light/buzzer problem at
> idle speed which was quite common and
took it to a VW specialist (NOT
> the dealer) who solved the
problem by rerouting some wires and adding a
> few more - that
solved the problem. Over the last three or four years
> the
light/buzzer came on spasmodically for short periods at highway
>
speed and went away if I simply turned off the engine and restarted -
> this happened at intervals of three or four months. Now, however,
the
> problem has returned and will not go away like it always
did. I have
> the Bentley manual which is some help but also
somewhat confusing - I'm
> still not sure whether I have one oil
pressure switch or two (I think
> maybe two).
>
> In trying to figure this out myself I discovered that guy who
fixed the
> low speed light/buzzer problem disconnected the
pressure switch under
> the pulley and grounded the lead it had
plugged into. In reading the
> manual I see that doing that
eliminates the .9 bar switch but that is
> recommended only to
check the functionality of the oil pressure system
> so I took out
the ground and reconnected the switch lead where it
> belonged but
that didn't solve the problem either.
>
> Has anyone
encountered this problem and what was the cure?
>
> If
anyone can point me to a competent mechanic north of Boston I'd be
> grateful as I need to be able to drive over 30mph without the
buzzer
> harassment. I don't mind paying to have it fixed but
through past
> experience I have absolutely no confidence in the
local VW dealer and
> the guy who I worked with before closed his
shop and is nowhere to be
> found.
>
> Thanks
for any advice.
>
> WTW
>
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