The plastic pipes fail and yours are likely failing now. The problem is
with a steel insert that is inside each end of the plastic pipes. It is
there to support the plastic where the hose and hose clamp goes. The
inserts can slowly push out and often crack the end of the pipe in the
process. This happens sight unseen, until the hose pops off suddenly or
at least starts to leak. I have seen it happen even with new VW
replacements just a couple years after they were installed.

The plastic pipes are not sold any longer. Even while they were still in
the VW parts chain people started making stainless replacements.

Mark

Dave Mcneely wrote:
> ---- Jay Brown<badkarma@TTLC.NET>  wrote:
>> How about internal ceramic coating as a barrier against galvanic corrosion?
>> If it's tough enough to survive inside the engine or exhaust pipes, the
>> coolant system should be a walk in the park by comparison.  A quick google
>> search pulled up these guys
>> http://www.classiccoatings.com/ceramic.html#internal.   Seriously though, I
>> think we are looking for things to obsess about at this point.  I will
>> change my coolant every couple years and hope for the best.
>
> ".... resistant to chipping .... " means that it can chip.  I don't think we want bits of glass in the cooling system.  I'm with those who say keep it clean, that is, change the coolant regularly.  That said, I've not had a problem with the plastic pipes on my '91 Volkswagen Vanagon GL Campmobile.  What again is the reason for replacing those with stainless steel (other than the "cool" factor, which seems odd since only the owner will know about them)?  My plastic ones have certainly never leaked.  Of course, older models had steel pipes, which probably corroded.
>
> DMC
>