I've had to work over the battery cables, ground cables and charging
wires on my 85 .and other vans.

a few points..
get a diesel vanagon battery with around 600 cold cranking amps at least.

one limitation of the early vans ( pre 86 ) is that they have a small
battery cable from battery to starter.
I ran an extra cable..I have two parallel battery cables going to my
starter in my 85 Vanagon.

make sure the 'charging wire'  from Alternator to starter is good ..as
in bigger than normal ..

make sure the trans ground strap is good.

try to have a robust charnging voltage ..at least 14.0 volts ...14.5  is
nice.
See what it is at the alternator and the starting battery ..
should be more than half a volt less at the starting battery.
If you have an aux battery .....that battery and isolator device can
cause 'issues' about starting ..maybe.
Take that out of the picture until you get reliable starting well
established.
I prefer a manual battery switch for an aux battery charging  myself.

this usually does it...working over battery cables and charging wires.
I also had to add a small toggle switch for my radio ..
the one I have draws a small current all the time for memory ..
it will make my 85 very hard to start in a week..
so I have it switch 'hard off' via a small toggle swithdc most when van
is parked.

basically though ..
if you have a good hot battery,
a quality new rebuilt starter..
and *fairly robust charging voltage* ..
that usually does it.....working over the battery cables and charging
wire/s.

it's somewhat characteristic of all car brands ..
as they add more and more..
the last year before a big upgrade is on the weak side...
the fatter main battery cable and more robust starter to spin a 2.1
engine ..versus the smaller main battery cable and smaller starter in an
85 fits this.
85's are good though ..
first year of the better sliding door..last year of the better round
headlights.
Any engine will fit of course
( I run a 2.1 wbxr on the early Digijet EFI and 1.9 cooling system ..and
love it, for a waterboxer ) ..
the only thing not really 'better' on 85's is the old style fuse box.

have fun !
scott
www.turbovans.com

On 4/13/2012 1:44 PM, Ken Olsen wrote:
> I'm pretty baffled. My 85' Westfalia waterboxer has been turning over
> slowly since I bought it several years ago, but it has finally got to the
> point of stranding me. It is behaving like a low battery, but I think I
> have ruled that out.
>
> Symptoms:
> Turns over very slowly, sometimes stopping (or catching?)
> Runs fine when started.
> Battery voltage looks good. Jumping doesn't help.
> Voltage at starter matches battery.
> Turns over slowly with:
>      - spark plugs removed.
>      - fresh battery jumpered directly to starter.
>      - WITH NEW STARTER INSTALLED!
>
> What am I missing?
>
> Thanks,
>
> Ken in Oregon.
>