What we normally would call a head gasket on a waterboxer is actually a
cooling system sealant gasket.  It does not contain compression, but simply
holds coolant in the jacket surrounding the cylinders.  If one of these is
starting to give way, you will not notice a change in drivability (unless,
of course, one fails catastrophically).  You will need to pull the head on
the leaking side and replace gaskets.  If you're doing the job, you should
almost certainly go ahead and do both sides.  You can check the archives for
more info on this - it is not a job for the faint of heart!

Karl Wolz

.  My
question is: can I have a bad head gasket without any symptoms (such
as overheating, white smoke, loss of power)? Am I just not noticing
the symptoms?