Date: Thu, 18 May 2006 00:27:19 -0400
Reply-To: Dennis Haynes <dhaynes@OPTONLINE.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <dhaynes@OPTONLINE.NET>
Subject: Re: maybe too much information is worse...
In-Reply-To: <6da579340605171740q297e7c0exd61b0bb03a33e771@mail.gmail.com>
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-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
Of John Bange
Sent: Wednesday, May 17, 2006 8:40 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: maybe too much information is worse...
On 5/15/06, Dennis Haynes <dhaynes@optonline.net> wrote:
>
> Where is the oil temp sensor located? Is it really seeing oil temp or
case
> and some other temps? I would be concerned about the oil pressure
though. 28
> psi ( 2 Bar) at 4,000 rpm is a minimum. a a healthy engine should be
able to
> maintain almost 10 psi/1,000 rpm except under extreme conditions.
Oil temp sensor is just the simple drain plug replacement type. I reckon
the
bottom of the sump there ought to be seeing actual oil temps, no?
Engine oil is actually a lousy conductor of heat, in fact, oil is an
insulator. The oil on the bottom will "skin" and a layer will not move.
Air flow over the sump will also contribute to the case being cooler
that the oil in it. The drain plug sensor will give a good indication
but the actual oil temps may be 10-20F higher.
The 20+psi was at 3000rpm or so, and I'd say that grinding up the grade
out of Baker, CA in 109F heat to be pretty extreme conditions.
As long as the radiator can keep up, the outside temp will have limited
effect on oil temp. The oil to water heat exchanger does a good job
until the thermal load on the oil exceeds its capacity. Then oil temp
can sky rocket.
For the "10psi per1Krpm", what grade of oil is that?
10 psi/1,000 rpm is a general guide line for any engine. If that can't
be maintained, oil viscosity is the first thing to consider. The Vanagon
engine is a low tolerance, (sloppy) engine further compounded by an
engine case that expands and lets the bearings get loose along with an
oil pump design that is extremely viscosity dependant. The pump can
actually stop pumping if the oil gets thin enough. The owners manual
calls for 20w-50 for most climates and even recommends straight 40 for
the tropics. With today's multi-weights, the 20w-50 or synthetic
equivalent is better than the straight 40.
I reckon 10w30 would be like water at 220F. I put in a mix of 5w15 and
10w30 syntetic for the trip in anticipation of the heat. I watered down
the straight 15w50 because I was seeing something like 75psi+ cold.
Again, modern oils are highly engineered products-that work. Mixing
different viscosity multi weights can make a real mess. There is nothing
wrong with 75 psi on a cold engine. A few minutes will take care of that
anyway. Just drive gently and avoid high revs until the temp gauge
clears the white bar. Before the inline engines had hydraulic lifters,
those engine ran at 90 psi hot! I would not worry about excessive oil
pressure until you 100-125 and still climbing which would also indicate
a relief valve problem. The Mobil 15w-50 is rated to flow down to -35F.
I have used it as low as -4F. In regular weather below the 20's I would
use a 0w-40, (Mobil 1 European car formulae) or 10w-40, (Mobil 1
extended performance). BTW, oil analysis is indication that a 7,500 mile
change interval is the reasonable limit for the Water boxer. Even the
synthetic is suffering from oxidation and nitration, most likely due to
high upper ring temperatures.
At any rate, I'm now at Bryce Canyon scabbing off their wireless
internet at
the gerneral store. Van made it up to 8000ft jst fine, though the
coolant
has a tendency to boil like crazy when I shut the engine down, and a big
piece of the horsepower seems to have stayed behind in Zion where it's
only
4000ft...
A normally aspirated engine will lose 3%/1,000 ft altitude.
Enjoy your trip!
Dennis
--
John Bange
'90 Vanagon - "Geldsauger"
