[V6-12v] Bizarre Cooling System Problem

[Wilfried Link]

Cooling mystery continues: 2Bennett Audimotive tests
revealed no sign of head gasket trouble. I will
tonight replace the O-ring on the front of the heater
pipe just behind the water pump, just as I did the one
on the coolant pipe behind the thermostat. Both can be
done without removing the intake manifold by unbolting
the pipes from their moorings on the cylinder head and
block and pushing them back in inch to replace the
rings. Lube with plenty of spit, or something as
begnin. I don't know if they can be pulled out of the
car entirely without removing the manifold. The heater
pipe maybe, but the big black coolant pipe I doubt.

Wil
1995 A6