Date:         Wed, 27 Jun 2001 22:36:26 EDT
Reply-To:     FrankGRUN@AOL.COM
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Frank Grunthaner <FrankGRUN@AOL.COM>
Subject:      Oil Level Issue and Comment
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Several posters are correct in referring to the problem of aeration by the
crank and aeration of the oil. The impact (as others have mentioned and
examples cited by Smokey Yurnick) is severe in a great loss in cooling
ability and a viscosity reduction. In addition, the gear type oil pump can
lose pump pressure because of the breakup of the side wall seal (gear-to-gear
and gear-to-pump body) with the excess gas included in the aerated oil. This
effect is universal for overfilled pans and is exaggerated with immersed cam
gears.

The windage tray and a well controlled oil level (or a dry sump) can
eliminate the problem and return lost horsepower/torque which had been
expended in whipping up the oil. This effect is also much more significant
with classical paraffin-based oils and worst for single viscosity grades.

I raise all of this again because I have literally seen the effect and am
trying to generate a video. In my I-4 conversion, laying over at 55 degrees,
the oil level in the oil pan is closer to the crank than in the normal mount
angle (with the regular oil pan). When using a I-4 engine from a previous
transverse installation, there is the problem of the oil dipstick tube. In my
case, I cut it off and sealed it with PCV tubing. Later, when I added the
windage tray to my RV engine, I was concerned as to the proper fill level.

To wit, I took an Olympus Borescope (about 1/8 inch diameter, including light
and image conduit) and put it through the dipstick port (details in the
archives). This let me image the oil level statically and let me watch all
hell break loose when the engine was running. Interestingly, at the point
about halfway between the full and add marks on the vanagon diesel dipstick,
the oil level just came up to the base of the windage tray, statically.

When the engine was running at idle speeds, clear oil was spraying/pouring
from the windage tray slots. As the engine revved up, the oil seemed to bias
up on the side in the direction of crankshaft rotation. By 2,000, it was just
sheeting and the oil level had dropped by about 1 cm or so. When I added the
rest of the oil (about 0.5 quart) the oil became cloudy but dark. Lots of
froth, and oil everywhere with strong jets of oil coming out of the windage
tray baffles. the Oil level was now burping - oscillating up and down - maybe
rapid sloshing is the best term (rapid waves going front to back and side to
side). When I overfilled by 0.5 quarts, all hell broke loose. The oil now
foamed, it came from everywhere as if in a hurricane. No well defined
streamers from the windage tray, and the color was now gray or nearly white.
The level in the sump was now very difficult to judge, but seemed several cm.
higher than before. I had been using the edge of the Al oil pan for a
reference, but I could no longer see it. In addition, the pressure in the pan
increased and began to squirt oil out of the dipstick hole and everywhere.

Here the experiment was truncated by a few terse and well chosen words and
stock phrases from SWMBO. I had not setup to tape the event, so I have no
images to show. My son and I intend to duplicate the event as we work out the
oil return issue on the Audi turbo project. This time we will tape, and cover
the rear of the Westfalia with plastic. (What a mess!)

Anyway, the actual oil level is a big deal. Although I would never suggest
the engineers got something like this wrong, I will note that crankcase
pressure is a major part of this problem. Older engines with excessive blowby
will show the aeration onset earlier. Again this effect is exaggerated by the
boxer configuration. So wrong oil, high blowby (bad rings), high temperatures
(high working load, high ambient) and a clogged ventilation system will all
conspire to enhance the effect.

Oh well, I'm quiet, hope this helps clarify the problem slightly,

Frank Grunthaner