Lean mixture causes corrosive oil? Good imagination! A lean mixture will
only affect the oil if it is causing the rings to get so hot that the
oil is getting burned. At that point, the engine will be suffering from
a lean miss- fire. A lean miss-fire can possibly cause gas to get past
the rings, especially on a cold engine. If the engine is running
correctly and the catalyst is good, the CO after the Cat will be near 0.
If measured before the Cat it is usually somewhere around .3 to .7 but
this is because this is the best that the ECU can control it. A lean
mixture can cause warped-burned valves and melted pistons. So will
over-advancing the ignition timing. Over the years, I've have yet to see
a WBX engine ever wear out the pistons, rings, or cylinders. Whenever
they go bad, it has been a failure such as stuck rings from excessive
deposits, excess heat, melted pistons from excess heat, or holes in the
pistons from coolant getting into the combustion chamber. I don't recall
how many miles you have on your engine but your compression readings
indicate that you engine suffered what I'll call an "Event" that is
bringing on the failure. Your advancing the timing has contributed to
this event. One consideration with WBX is that under load, you can not
hear it ping until the ping is really bad. At this point, engine damage
is occurring.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
Of Smola, Tony
Sent: Wednesday, March 13, 2002 1:26 AM
To: vanagon@GERRY.VANAGON.COM
Subject: ENGINE FAILURE-could be caused by too lean air-fuel mixture

A machine shop here in the San Fernando Valley says that if the CO is
too
low like .01-.05....something really low like that, you
run the  risk of too lean a fuel mixture, which could cause the pH of
the
oil to become corrosive and hurt the
bearings.  He did not notice any thrown rods on the 2.1L, but he said if
there was a lean FI
that the engines suffered from bearing failure, cracked heads between
the
seats...

So make sure your CO ( carbon monoxide) on your emissions is between
0.7
and 1.0..........

Malibu Tony    85' Westy   1.9L      finding out lots of stuff about the
motor and how to make it really last........anyone have any 1.9L
bearings
or a complete 2.1L w/ all the hardware?