At 07:51 AM 01/04/2000 -0800, you wrote:
>1984 Vanagon with new (rebuilt) engine with less than 30K on it.  Two years
>old.  Compression on number 4 has dropped to about 60 pounds when cold.  Run
>the engine for 15-20 seconds and recheck and the pressure is up to almost 90
>pounds.  Sounds like valves but all of the mechanics say it is the rings.
>
>Also having a cold starting problem.

William, the poor combustion from the weak cylinder is putting off excess
gases that are measured by the oxy therefore fooling the computer which
feeds a weak mixture to the three good cylinders. Set the motor with open
loop at a rich setting for temporary improved running and budget a teardown
to fix the compression leak/s. A leakdown test will identify the
compression loss as rings and/or valves.

You won't know fer shur if the head might be cracked until you get it off
of there.

Scutinize that motor and cooling system very carfully. If you see any
coorosion at any of the head nuts or water pump or sensors or hose
fittings, pull both heads for protection from a short term failure due to a
"cheaper" half fast quicky one sided fix. Scrutinize the head studs as
well. Any rough cooroded area of minimal proportion is a stress riser
wanting to crack and spoil your reassembly pronto.

Do check with Bob at Boston Engine? as he appears to have the highest level
of knowledge on the list with the WasserBoxers.

T.P. Stephens aka Doktor Tim
Surveyor, Mechanic, Poet, Philosopher
San Juan Island, WA