Hi All,

The head corrosion in wassers is the fault of the design, NOT of any
particular aspect of coolant/maintanance etc.  This is not to say that
neglecting to change the coolant often enough is not part of the problem.

The use of thick soft rubber gaskets in any corrosive enviroment is the
source of the problem.  Have a look at ANY alloy head and block in ANY car
and I'll bet you will not find another fat rubber gasket. They are all
thin/flat/highly compressed gaskets. The coolant is simply unable to get
between the gasket and it's sealing face, unlike the VW wasserboxer.

On our engines this leads to little pockets of trapped coolant, which go
into overtime doing corrosion damage. The corrosion inhibitors in the
coolant get depleted locally, and full galvanic corrosion sets in, in highly
localized cells. The aluminium 'rust' takes up more space under the gaskets,
lifting them off a bit and letting further seepage/pitting occur.
Eventually it spans the seal face, and leaks, real fast once the pressurized
coolant erodes the alum. oxide out of the way. Stiffening, aged rubber, and
thermal contraction in cold weather, also help the corrosion further bye
reducing clamping force over the gasket.

Bad original design, plain and simple.  The cure is a coating, VW tried
cadmium, I doubt it lasts long since it is thin, and fretting wear due to
micromotion will wear through it. Ceramics and epoxy work well.

<Soapbox ON>

  The reason we have so many little hoses/pipes/flanges joining the case
sides, and to/from the water pump, is because this engine was not designed
as a wasserboxer! We got a bandaid solution, not a new design.  I LIKE
German cars, respect their engineering and trust their reliability, (I've
also had too many to dare admit otherwise) but the VW wasser was
ill-conceived.  At the risk of irritating folks (do I care?) go look at a
Subaru engine.  It has 2 large diameter rad oulets and 2 1/2" heater
outlets.  Everything else to do with the coolant is fully within the block.
The heads are clamped down hard onto thin gaskets, using bolts into a block,
not studs that rust out.  They last 300K kms with only basic attention.
This is how good design works.

Do I want Subaru engines in my vans? yes, until I can get a VW-TDI in there.
I just don't want a VW wasserboxer in an otherwise excellent vehicle, nor
will I pay $$$$ to keep one there! And 95HP out of 2.1l is pathetic nowadays
to boot.

<pant, pant, end of rant>

bye folks, Tim