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Purging through the filter on an 05 Passat w/ lift pump

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January 31, 2012 - 12:17am
b_r_ryan
b_r_ryan's picture
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Joined: 05/31/2009

vital stats:

  1. 2005.5 Passat Wagon
  2. 125k mi.
  3. 40-60k on wvo

I've been running my passat on wvo for 3 years with (mostly) great results.  The only issue I have right now is that I've always gone through vo filters like nobody's business.  I get like 1000-1500mi. out of them.  I know it's not an issue of filtration cos my friend runs his 03 Jetta (no lift pump) using the same vo on the same filters for 1/2 year +.  I'm pretty sure the issue is the purge cycle.  On a Passat the diesel only goes through the pex line back to the tank, skipping the filter and lift pump and leaving that as a separate loop.  I think the cold (I live in RI) and static state causes the vo in the filter to wax up and clog quickly.  If the filter were filled w/ diesel when not operating (as in an 03 Jetta), it wouldn't clog as often.  I've heard other things about people doing a purge through lift pump and filter so I'm pretty certain it's possible.  These two (really crude) drawings represent how I think the lines should be routed:
Old Plumbing           new plumbing
This is how I did it yet when I attempted to run it on warm VO, w/ a warm car it stalled out.  Am I totally missing something?  Any help would be appreciated.

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January 31, 2012 - 5:48pm
#1
JR3342 (not verified)
JR3342's picture

Looks right.probably got air trapped in the loop.run a cple flush cycles. Then try it.backwashing the filter can break the element not a good idea.if no fphe your losing alot of heat not lopping the oil thru the filter.all the crud in the filter get pushed back to the tank to replug the filter later.

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January 31, 2012 - 9:30pm
#2
veggpwr
veggpwr's picture
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Joined: 09/27/2010

Assuming it is a GC system, referring to your diagram, diesel purge line should be connected to valve B nc port.
Line to engine should be connected to valve A nc port. Your new routing diagram will work at diesel mode, will NOT work at 
veggie mode since you are pumping oil to the IP and to the "return from engine" at the same time. Also at purge mode you
are purging against the normal flow of the lift pump.
The solution with reference to your new diagram:
        Disconnect the two hoses from the VO lift pump.
        At "T", disconnect the hose to filter and the hose to engine.
        Connect PEX to filter(in)
        Connect filter(out) to "T"
        Connect "T" to lift pump (in)
        Connect lift pump(out) to valve A nc port (line to engine)
I have the same "T" setup on my 05 Cummins GC kit.

__________________

'05 Cummins CTD 24V HPCR RAM 2500 QC SLT SB Black 4X4 48RE  325 hp  610 ft.lbs
GC Kit  + 3rd Tank WVO(80%)/RUG(20%)  +  Co-Pilot 
3-Tank Operation managed by Co-Pilot: Blending(warm up) / Veggie(hot run) / Diesel(purge for next start)
Smarty Jr  40/70/100 hp
 

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