[Vwdiesel] injector lines.

[William A. Thompson]

I have seen what you are talking about in my Rabbits too ... and it is as
Nate said ... "appeared to be the result of the manufacturing process" ...
"The excess metal was right at the very ends of the line".
This is the burr that is left over from the tube "cutting" process that has
not been deburred afterward.
If you have ever seen tubing being cut ... especially with a "hand" tubing
cutter ... the sharp edged wheel (like a blade ... not toothed like a saw)
that does the "cutting" doesn't actually cut ... per se ... it is more of a
"pushing the metal of the tubing to the sides of the "cutting wheel" ... as
the wheel is forced into the tube ... as it and the tubing spin against each
other during the "cutting". The result is more of a deforming of the tube to
create a parting crease ... and some of the metal is pushed evenly, all
around, into the I.D. of the tube. After the tubing is "cut" ... the opening
in the "cut" end has some of the tubing metal deformed evenly ... and all
around ... into the opening ... effectively making the inside diameter right
at the cut end ... a bit smaller than that of the rest of the tubing. The
more pressure put on the wheel while "cutting" ... the greater the burr and
smaller the I.D. when done.
After cutting tubing it should be deburred on it's I.D. to remove this
"burr" ... as standard practice ... to get flow volume back to normal ...
and I have seen problems with "eddies" that form on the downstream side of
the burr in certain other (flow) applications.
The deburring tool looks very much like a drilled hole deburrer ... but with
a nose on it to fit the tube I.D. ... and a shoulder ... both with cutting
flutes on their O.D.s to open up/remove the burr.
I am not sure if the volume of fuel flow ... for the small instant of each
injection pulse in our Rabbit applications would be adversely affected ...
but us perfectionists can't sleep with the burr there. By the way ... it is
the little things like whether or not the burrs are removed ... that I
evaluate the quality of parts from a supplier. Although that one extra step
in the manufacturing process saves them time and money ... seeing something
like that makes me wonder about the things I can't conveniently see.
A "handy" person may be able to use a drill and motor to carefully open up
the burr ... even so ... I prefer the tool made for the job. It is easier to
control how much you open up the burr to match the original tube I.D. High
pressures inside the tube ... with fatigue from many ... many cycles of
pressurizing ... and the greater propensity of the ends tubing's walls to
deform even more, when thinner, as the fitting is tightened onto the
injector ... would make this method preferable.

Bill
Sedro Woolley, Washington

----- Original Message ----- 
From: "cass" <iscass at shaw.ca>
To: <vwdiesel at vwfans.com>
Sent: Monday, March 29, 2004 5:55 PM
Subject: [Vwdiesel] injector lines.


> hi..
> ok..so  after trying the 'tighten a lil more' technique...i pulled the
injector lines to had a closer look...
> ...after inspecting injector lines i can see a 'lip' on the part that is
supposed to
> 'sit' in the injector.
> so..
> with my clean ,tiny tools (was a silver/goldsmith in past life ;o)  )
> i got rid of that lip..
> but i noticed all the holes are different sizes(in the lines)
> would it be bad of me to drill them out?
> are they supposed to be different sizes?
> waiting with drill in hand....  :o)
>
> (cleaning lines well afterwards ,of course!!)
>
> thanks..
> cassie
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