Date: Thu, 3 Oct 2002 09:19:16 -0700
Reply-To: Stuart MacMillan <macmillan@ATTBI.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Stuart MacMillan <macmillan@ATTBI.COM>
Subject: Re: Does a worn pressure relief valve cause Oil pressure buzzer?
In-Reply-To: <3D9C5C1F.9383BA12@highspeedplus.com>
Content-Type: text/plain; charset="us-ascii"
Mark,
This is pretty unlikely, but possible. It would take a lot of grit in the
oil to wear the valve enough to cause this. Usually relief valves stick
closed, but springs can break too. It's an easy replacement (buy the proper
tool, it's cheap) if you want to try this, but if you find a very worn
relief valve then your oil pump is shot too, since it pumped the same grit!
Unfortunately, the WBX is not a very tight engine under the best conditions,
and the expansion of the alloy case causes oil pressure to drop as it heats
up, further opening the already loose tolerances. Since it is the main and
rod bearings that affect oil pressure the most, as they wear you start to
see the pressure drop, and this is more pronounced the harder the engine
works. The rod big ends start to get oval with use, and this is probably
the main cause of low oil pressure. See my article on Tom's pages:
http://volksweb.relitech.com/21rodbrg.htm
VW was well aware that they were pushing the limits of their design when
they upped the displacement from 1.9 to 2.1 and added an oil cooler and a
second sender with a buzzer. This leads me back to the need for an oil
pressure gauge to accurately monitor the condition of your engine.
The new sender at the oil pump measures the highest pressure the pump can
deliver, and everything else downstream gets less. The sender between the
pushrod tubes measures the pressure at the main bearings, where the most
severe loads are, and this is where the gauge should be installed. Further
downstream are the lifters which need oil pressure to maintain zero lash,
and through them oil goes up the pushrods to lube the rockers. The lifters
can normally drain down after periods of sitting, and should pump up
immediately if oil pressure is good. Quite often they can take a few
minutes of running to do so, every WBX I've owned as done this occasionally.
Marvel Mystery Oil can help this, as it is a solvent that can clean out
"stuck" lifters. Much is in the archives on this.
Get a gauge and remove the uncertainty of your situation. As a quick fix
try mineral 20w 50 oil, the synthetics are physically much thinner, and this
can have a dramatic effect on the WBX oil pressure.
-----Original Message-----
From: Mark Keller [mailto:kelphoto@highspeedplus.com]
Sent: Thursday, October 03, 2002 8:03 AM
To: Stuart MacMillan; Vanagon Mailing List
Subject: Does a worn pressure relief valve cause Oil pressure buzzer?
Stuart,
I am having this issue on occasion, with similar conditions: heat
soaked, i.e. long climb, Mobil 1 syntheitc and get the buzzer just after
letting off of the throttle, i.e. cresting the hill. I'm also having
very infrequent but associated with the buzzer episodes a split second
valve clatter like once a year, but it will happen two or three times
then not again for a year.
Can you shed any light on the possibility of these events being caused
by a worn pressure relief valve.
Sincerely,
Mark Keller
91 Carat
| 
