At 09:44 AM 11/16/2001, John Baker wrote:
>Head Gaskets? What the hell are head gaskets???

In case it wasn't clear in context, the "head gaskets" on the waterboxer
are H-section rubber moldings.  VW achieved cooling for the cylinders by
stripping off the fins and building up the case to form a sort of aquarium
extending out to the head.  The head itself is a proper design with
internal cooling passages, whilst the rest of the system uses external
piping to carry the coolant around.

The "aquarium" wall stops a couple millimeters (?) short of the head, and
the gap is taken up by the aforementioned rubber molding.  This gives the
best of all possible worlds -- a thick-section flexible gasket with narrow
sealing surface, subject to considerable thermal cycling (since the heads
are mounted on the cast-iron cylinders, they move much less than the
aluminum case wall with temp changes; so the gap is continually changing).

Coolant eventually begins to seep under the lip of the seal, then corrodes
which makes a high spot letting more coolant advance, corrode, rinse,
repeat.  It works the same way that rust pushes out under paint.  No doubt
the gasket itself loses flexibility with time, also.

david

David Beierl - Providence, RI
  http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"