Hello,

        I have a mysterious thumping sound on the underside of my van which
happens about every 5 minutes or so when I am driving around town.  It
doesn't seem to be originating in the same place everytime, in that it
sometimes sounds as if is close to the drivers side, other times it sounds as
if it is on the front passenger side, and still other times it sounds as if
it is the rear.  It has the sound of something which is dropping into place,
kind of like a gear finally engaging in an automatic transmission which isn't
working right.  It's a thump on the underside of the van, which might happen
every 5 minutes or so (I can't make it happen, and it seems to happen at
random).  It's not a sound like something is actually hitting the underside of
the van, but more like something under there is jerking into place.

        It seems to only happen when I'm sitting still (at a stop light
usually) but that may just be coincidental since I might not notice it when
I'm driving.  It's not a huge noise or percussion, but definately noticable.

        Other than the suspect noise it runs fine (although I'd think that it
should shift smoother, but this is my first Vanagon and it just may be the
nature of the beast).  I was told by a tire dealer (when I was getting an
alignment) that the belts in my tires were slipping, and that this was the
source of the noise.  I balked at this since it seemed like they were
primarily interested in selling me new tires, but maybe someone can confirm
this.  I want to take care of this before it turns into a serious problem, but
I honestly have no idea as to what would make such a noise.

        BTW, it is a 1990 Vanagon, 4 speed manual, 2.1L engine.

        Any suggestions or guesses would be appreciated !  This list has been
a very good source of Vanagon info, and I appreciate everyone's interest and
responses in the past.

Kind regards,
James Adams