Date: Sun, 30 Nov 1997 20:43:34 -0500
Reply-To: SyncroHead@AOL.COM
Sender: Vanagon mailing list <Vanagon@Gerry.SDSC.EDU>
From: SyncroHead@AOL.COM
Subject: Re: 89 Wolfs/Newbie ??
In a message dated 97-11-30 12:20:37 EST, manx@CATS.UCSC.EDU writes:
> 1) I get about 17 mpg in the city and 20-22 on the highway. Is this
normal
> for this model? I may have to rethink using premium fuel so I don't go
broke.
I'd encourage you to run the lowest octane fuel that your van runs good with.
Having a higher octane grade fuel than the vehicle needs is just wasting
your money. Try a tank of regular 87 and go up a steep hill with a load and
listen (along with passengers - they're a convenient part of the "load")
dilligently for pinging. If you don't hear any, simply continue using the
87. If you do hear some, next tank try the 89 mid-grade fuel and repeat the
test. I find that my vans run fine on 87 octane.
> 2) I have that damned oil light/buzzer problem.
<big snip>
> Any suggestions on how to chase this down?
Yes. Rig up (or have your mechanic rig up) two temporary test lights directly
to the two oil pressure switches and monitor their status, bypassig all the
electronic circuitry and the rest of the van's wiring. This will tell you if
the oil pressure switches are actually engaging or not. If they are
indicating too low an oil pressure, it might be:
1. Bad oil filter, try a different brand - not Fram.
2. Bad oil pressure switch(es) - try replacing.
3. Actual low oil pressure - replace engine. We'll maybe something less
drastic, a rebuild. :-)
Here's how the oil pressure systen should work:
The operation of the Dynamic Oil Pressure System is described in Bentley
section 90. The operation of the oil pressure switches is described in
Bentley section 17.
I use the term "described" here pretty loosely here, because they do a very
poor job.
The dynamic oil pressure monitoring system gets inputs from two pressure
switches. One switch is closed with no oil pressure and opens when oil
pressure rises to about 0.3 bar, called the .3 bar switch. The .3 bar switch
is located between the left (driver's side) two cylinders.
The other switch is open with no oil pressure and closes when oil pressure
rises to about 0.9 bar, thus called the .9 bar switch. The .9 bar switch is
located below the water pump & crank pulley, near the oil pump.
The monitoring system seems to only "look at" the .3 bar switch below 2000
RPM and ignore the .9 bar switch. Above 2000 RPM the active switch is the .9
bar switch while the .3 bar switch is ignored. Below I've described a
properly operating monitoring system. Note that I say "monitoring system"
because some of the conditions describe an abnormally low oil pressure
condition.
A. Ignition ON, engine NOT running -- or -- engine running at LESS than
2000RPM
.9 bar switch is ignored
1. Low oil pressure exists (below .3 bar), keeping .3 bar switch closed
Oil light: Flashes
Buzzer: Silent
2. Normal oil pressure exists (above .3 bar), opening .3 bar switch
Oil light: Off
Buzzer: Silent
B. Engine running at MORE than 2000RPM
.3 bar switch is ignored
1. Low oil pressure exists (below .9 bar), keeping .9 bar switch open
Oil light: Flashes
Buzzer: Sounds
2. Normal oil pressure exists (above .9 bar), closing .9 bar switch
Oil light: Off
Buzzer: Silent
There does not appear to be a condition in a normally operating monitoring
system when the light should be on steady.
Good luck,
Jim Davis
