As Bulley alluded to, all you have to do is look at VW of South Africa.  In
the early '90s when VW gave up on the waterboxer engine (stopped making it in
90 or 91) VW of SA started making Vanagons.  Since they didn't have the
waterboxer available (I am being nice and not saying they didn't want to use
it) they started putting in in-line 4 and 5 cylinder VW engines.  I have been
to at least one website where they had posted stories about these vans and
how reliable they were.  They are still using the in-line engine in Vanagons
today so they must be holding up fairly well.

As far as putting the in-line engine in a larger vehicle, I don't know if
this counts but my first car was a '81 diesel VW rabbit pickup (caddy).
Under powered, but the engine held up very well and didn't blow up at the
drop of a hat.  I know of many of these diesel pickups where the engines
outlasted the body (they had problems with rust at the shock towers).  I
remember loading this truck down with cement until it was a low rider, and it
was slower, but didn't complain.

Comparing a 1600cc air cooled engine to a water cooled engine is not a fair
comparison as far as I am concerned.  Air cooled engine tolerances are not as
tight because they can't be due to expansion issues, and air cooling is not
as efficient, hence shorter engine life.  I don't want to offend the air
cooled folks out there.  If you love your van, enjoy it.  But a watercooled
engine will last longer and have more horsepower while giving out less
emissions (that's why they stopped making Air Cooleds).  It is just a fact.

Thanks,
Ken Wilford
John 3:16
http://www.vanagain.com
Phone: (856)-327-4936
Fax: (856)-327-2242