Date: Sun, 7 Apr 2019 18:33:48 +0000
Reply-To: Keith Hughes <keithahughes@YAHOO.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Keith Hughes <keithahughes@YAHOO.COM>
Subject: Re: vanagon Digest - 5 Apr 2019 to 6 Apr 2019 (#2019-77)
Content-Type: text/plain; charset=UTF-8
I don't think it's quite that straightforward with respect to model years. My '86 Westy (August of '86) which I purchased in '93 as the second owner had the small outlet fuel tank which I'm sure was original. It had both the pre and post filters with the 'adapter' filter Ken describes. After years of ethanol mixed gas putting water into a system not designed for it, the rust issues started. Eventually had to replace the tank about 3 years ago when I did the engine conversion, and now I just have the can filter downstream of the pump.
But as Ken points out, while the upstream filter will keep crud out of the pump, unless you keep the replacement interval suitably short to ensure against cavitation, the 'cure' will be worse than the 'disease'. If you want to keep one upstream, I'd suggest a large clear plastic filter, for flow capacity and ability to visually check filter loading, and put the high pressure filter downstream of the pump in the normal position.
Keith Hughes
'86 Westy GenV Turbo (Marvin)
------------------------------
Date: Sat, 6 Apr 2019
18:16:24 -0400
From: "kenneth wilford
(Van-Again)" <kenwilfy@COMCAST.NET>
Subject: Re: Vanagon fuel filter mod
for my 84 Westy
So VW originally put a plastic cube
filter here that also works as an
adapter since the early tanks had a 7mm
outlet but the pump has a 12mm
inlet. However in 84 some vans
had a plastic cube filter before the pump
and a metal filter after the
pump. Probably because VW had decided to go
to an after pump filter but they still
had some 7mm outlet tanks they were
using up. After 85 they went with
a 12mm outlet on the tank, no filter
before the pump, but a metal filter
after the pump. Here is why I think
they did this. The filter before
the pump can clog and restrict the pump.
If this happens a perfect good pump
could cavitate and be wrecked which
would allow debris to go down stream
and into the injectors. So you have
this situation where a bad filter
causes the pump and injectors to be
destroyed. Now let's think about
what happens if you put the filter after
the pump. If pump goes bad, it
dies but doesn't destroy anything else.
Since there isn't a filter before the
pump, unless the tank is full is
rust, the pump shouldn't need a
filter. So you are protecting more things
with the filter after the pump.
VW decided that was the smart way to go so
I think it was a good move.
Ken
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