Howdy List,

This may have been covered but I thought another reference wouldn't hurt.

When I installed my Boston Bob 2.0 Air-Cooled motor last year I went over
every component and replaced/refurbished as best I could.  That work
included wrapping the exposed header pipe that runs from the heads to the
heat exchanger cover.  I see this sort of wrapping on a variety of engines,
especially of the high-performance flavor so I figured it had to be a good
idea.  I also had hopes of warmer cabin heat since more heat would be
transferred into the heat exchangers and I had hopes of cooler heads
(maybe).

What ended up happening was that the header pipes melted and cooled
repeatedly.  A week or so ago I developed an exhaust leak which turned out
to be a cracked header (under the fiberglass).  When I tapped on that header
it crumbled.  I pulled both heat exchangers and all 4 header pipe sections
that had been wrapped were easy to tap holes into and chip/crumble to bits.

I have since learned that I am not the only one to experience this problem
on an air-cooled VW.  A local air-cooled VW machinist reported of hearing
about similar melting headers when wrapped.

If anyone wants to see pictures I have a few that I can p-mail or post
somewhere online.

Jonathan Poole
'83 AC Westy