First thing, besides serious physical inspection,
is try to be clear about when it does it ..
Like 'just driving along smoothly' ?
or hitting a bump ?
when it shifts gears ?
going around a  corner at low speed ?
etc.
next ...
on this 'tries do to die when I put it in reverse' ...
Is that like it has a weak idle and it shows up more when you go to back
up ?.
or is that like this ...

  One failure mode that I have seen in automatic transmissions in
vanagons is strong binding or resistance in thetransmission ..when
trying to back up, and also ..at the same time,  ATF getting into the
differential section of the transaxle.
  You really don't want that happening.

For easy stuff to do ..check trans ATF level.
for 'getting it off the ground and getting under there' ..
check Differential Oil Level and quality of that gear oil ..
wiggle rear wheels checking rear whl bearings..
inspect CV's and CV joint boots etc.

for those interested in details -
I just had a case where a guy bought a used auto trans for his 90 Carat
with DOHC 2.5 Subaru engine ..
he said that used trans went about a block.
  That junkyard-suppled trans in my hands now ..in the differential
section the pinion shaft bearing by the pinion gear is totally blown out ..
the cage for the rollers is just shrapnel, half the rollers are gone
from the bearing ..
and it's had ATF getting in there too.  If ATF gets in the Differential
Section ...
I would imagine it would not take long for that one roller bearing, by
the piniongear, which has to be under quite a bit of load, to fail.

It will likely be less expensive to get things checked out carefully
before anything totally fails.  And I hope it's not some big serious
expensive issue !

scott

On 1/30/2013 7:57 AM, Sondergaard, Arlene wrote:
> I have an automatic transmission.
> I have been having trouble backing up--tries to die.
> If I back up and turn the wheel a little bit it I hear the belt also.
>
>
> On Wed, Jan 30, 2013 at 7:50 AM, Mike S <mikes@flatsurface.com> wrote:
>
>> On 1/30/2013 10:13 AM, Sondergaard, Arlene wrote:
>>
>>> On the freeway this morning the passanger side rear wheel clunked like I
>>> hit a rock.  It happened 2 more times.  Got off freeway to examine tire.
>>> Pressure around 45 tire, looks normal, grab and shake-no give.  The belts
>>> look o.k.    Drive the backroad the rest of the way to work for lower
>>> speeds and i happened again 2wice.   What could be going on?
>>>
>> When my manual transmission went (the 3-4 hub, a common problem), a
>> similar thing happened, it felt to me like a rear wheel was binding up
>> briefly. Happened several times. Not long after, and I couldn't shift into
>> 3/4.
>>
>> Do you have a manual transmission? Any change/difficulties getting it
>> into/out of 3rd/4th?
>>
>>
>
> --
> Arlene Sondergaard
> CVO Sediment Lab
> 1300 SE Cardinal Court, Suite 100
> Vancouver, WA  98683
> 360-993-8943
> asonder@usgs.gov
>