[Vwdiesel] Fuel system check valves

[brian gochnauer]

After reading your response I looked at my 1.6NA, I didn't notice any
bubbles at idle (but line is dark brown discolored) but at just above idle
there is definately a stream of bubbles and it runs fine.

On 4/17/09, Terry Briggs <vbriggs at stny.rr.com> wrote:
>
> no worries, I understand all of that, it's the solid stream of bubbles
> I'm dealing with that bugs me right now. Once I get that taken care of,
> I should be set relatively speaking.
> Terry
> On Apr 17, 2009, at 8:02 AM, Patrick Dolan wrote:
>
> > Don't expect to ever eliminate the bubbles in the fuel line.
> >
> > ALL liquids at atmospheric pressure contain dissolved air and other
> > gasses.  Just the mere act of moving them through the little fittings
> > in the fuel system is often enough to liberate some (think of taking
> > the cap off of a carbonated soft drink).
> >
> > This is an incredibly important thing for any diesel enthusiast to
> > understand.  It is one of the reasons that our engine technology
> > lagged so far behind gassers for a century.  All of that liberated air
> > gets through the pump and enters the lines to the injector, and must
> > be compressed before the injection event can take place - resulting in
> > differences in injection quantity at the cylinder and differences in
> > timing between what the eingine THINKS is happening mechanically and
> > what IS happening in fact.
> >
> > Very few systems have ever dealt with this massive variable
> > successfully.  If you look at #3 injector on a VE pump TDI, you will
> > see how VWs suppliers cleverly did so.  The needle lift sensor in that
> > injector tells the computer EXACTLY when that one opens, and adjust
> > the timing for all cylinders to compensate.
> >
> > HPCR engines don't have any such concerns because from the time the
> > fuel gets to the high pressure pump, the fuel system pressure stays
> > above miscibility level, so nothing can break the solution.  Result:
> > possibility of exceedingly accurate timing (which today's piezo
> > injectors can utilize).
> >
> > Sorry for the lecture, but this is what I do for a living (make
> > equipment that degasses petroleum).
> >
> > ----- Original Message -----
> > From: Terry Briggs <vbriggs at stny.rr.com>
> > Date: Thursday, April 16, 2009 2:27 pm
> > Subject: Re: [Vwdiesel] Fuel system check valves
> >
> >> I've got line now, I'll spend saturday running lines and see where
> >> that
> >> gets me. Thanks for the direction and ideas,
> >> Terry
> >> On Apr 15, 2009, at 5:42 PM, LBaird119 at aol.com wrote:
> >>
> >>> In a message dated 4/15/2009 3:17:41 PM Central Daylight Time,
> >>> vbriggs at stny.rr.com writes:
> >>>
> >>>> I even get air
> >>>> bubbles on the filter side of the line when priming things with the
> >>>> mity-vac.
> >>>>
> >>>
> >>>   Leaks on both sides of the pump will end up with bubbles on
> >> the inlet
> >>> side of the pump.  :-P
> >>>      Loren
> >>>
> >>>
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