Date: Mon, 12 Sep 1994 10:13:31 -0700 (PDT)
Sender: Vanagon Mailing List <vanagon@vanagon.com>
From: hugie@lindy.stanford.edu (John Huguenard)
Subject: Re: oil pressure question
Martha Rubin Wrote:
> Would those of you with air-cooled vanagons AND an oil pressure
> gauge out there tell me approximately where your gauge reads
> while driving at highway speed?
Just back from a trip across the Sierra to Mammoth Lakes area
this weekend and here are some readings:
1981 Westphalia, Castrol 30W Heavy Duty Oil, 7K on VW long block.
Oil Pressure (psi):
Startup Cruising (about 60 MPH) Hill Climbing
65 (60deg F) 40-50 (after warmup) 30-40 (3rd gear,45-50 mph,5-7%grade)
70+ (50deg F) 35-40 (strong headwind) 20-30 (4th gear,45 mph,long climb)
35-50 (2nd gear,25-30mph,steep)
Head temperature (sender at spark plug #4!):
(<55 MPH) 250-300 deg F
60 MPH 300-350 deg F
65+ MPH 350-370 deg F
Head temperature never gets much above 360 deg F. During
normal highway cruising (no hills) is hovers very near 350.
Climbing up Tioga Pass from East (going from about 7000 ft to
10000 ft in less than 10 miles) was a serious test. I kept it in 2nd
gear the whole way at about 25-30 MPH. Oil pressure stayed above 40
psi and head temperature was 350 or less. However oil temp must have
been sky high (as David said), because when I stopped at the top at
the ranger station the oil pressure warning light came on at idle!
After a few minutes of relaxed driving the oil pressure came back up
and Dino ran beautifully.
My conclusions about oil pressure are simply that you should
use your head (the one on your shoulders ;). The situations where oil
pressure drops are pretty obvious, and you would know them even
without a guage. When climbing long hills and you are near the bottom
of a gear range (less than 50 mph in 4th or less than 30 mph in 3rd)
the oil pressure falls. This condition is pretty obvious because the
engine does not respond with more power when you step on the gas. IT
ALSO OCCURS BEFORE THE HEAD TEMPERATURE INCREASES VERY MUCH. I should
emphasize that this seems to apply to only long climbs (over several
minutes).
Now the only question relates to David's posting. David: You
talk about hill climbing at 48MPH in 3rd or 4th. In third the
temperature gets very hot, so what do you do? Stay in 3rd to keep the
pressure up, or go the 4th to keep the temp down?
ymmv
John Huguenard
1981 Westy
hugie@lindy.stanford.edu
