Thanks to everyone that responded.  The advice was "right on" on what to do
and try.

I realized I should have been clearer in my question:  I was wondering what
the "concave" valve stem observation might mean and how it might relate to
the problems with this engine.  (I understand it's impossible to "know"
until the engine is dropped and torn apart, but since the immediate plan of
action is to put the daughter's friend on a train and sell the camper on a
"where is, as is" basis out of my driveway, I may never get the
"opportunity.")

One respondent addressed the "concave stem" issue directly by suggesting
plain high miles, though I'd think you'd see that on *all* the valves, not
just one.

In thinking about this, since the valve adjusting screw is supposed to ride
on the valve stem slightly off center in order to spin the valve if some
kind of defect here, like not having all the rocker arm hardware in place,
could play a part in the problem?  If the valve adjusting screw was
more-or-less running down the center line of the stem, the valve wouldn't
rotate, the wear pattern could result in a concave stem, and the head of the
valve could burn just because a "weak spot" on the head of the valve could
be hitting the same "defect" in a valve seat.

I know this is all speculation, but I'd like to give whatever Pilgrim who
ends up buying this bus the best guess as to what's wrong.  (Without going
to all the work to really find out!)

Anybody want to buy a somewhat funky '78 camper?  :-)

Thanks again!

---------------------------------------------------------------
Tom Young                       '81 Vanagon
Lafayette, CA 94549         '82 Westfalia
---------------------------------------------------------------
----- Original Message -----
From: "Tom Young" <tomyoung1@comcast.net>
To: <type2@type2.com>; <vanagon@GERRY.VANAGON.COM>
Sent: Saturday, August 16, 2003 12:01 PM
Subject: [T2] Some basic TypeIV engine help, please

> Talking to my daughter's friend I'm told that the mechanic that replaced
the
> right-side pushrod seals told her that one of the valve stems on #3 -
don't
> know which one - had worn concave.  During the trip from Eureka to the SF
> Bay area she had to stop and put in a quart of oil every 15-30 minutes.
She
> also reports that a few miles from the house she experienced a significant
> decrease in power.  When I started it up this morning it was hard to keep
> running, had virtually no power - I'd guess it's running on 3 cylinders -
> and blowing smoke badly, which the friend says is new.