Hi All:

  We've just got back from a trip into the mountains and our '86 has started
a new sound for us to enjoy. It is an odd steady knocking that starts off
quietly and can get disturbingly loud quickly.  It has the following
characteristics:

  - it only appears on slow, long and steep uphill climbs (5%+ grade).
Doesn't show up if you gathered momentum and get over the hill at a good
speed.  .
  - quiets immediately upon release of the accelerator (no good when trying
to get over the hill)
  - sounds similar to a pump
  - always has a  steady rhythm

  It has appeared since we relocated to Colorado.  Altitude?

  If, whatever it is breaks, I fear being stranded.  Clues from the
educated?

  Dan