[Vwdiesel] Pump pressures, banjo jet sizes and injector leakage...

[mikitka]

Speaking of stoppers,  What can I use as a stopper for the number one
injector?  When I did my compression test mine plug finally split and is no
longer useable.  For now I cut a piece of 1/4 air brake line and plugged it
with a brass bolt that I ground down to fit, then I zip tied it to the mount
that you use to lift the engine out.  Looks crude but works, just was
wondering if there was something a little more attractive.

Nick

-----Original Message-----
From: vwdiesel-bounces at vwfans.com [mailto:vwdiesel-bounces at vwfans.com] On
Behalf Of Mark Shepherd
Sent: Thursday, October 21, 2004 8:22 PM
To: vwdiesel at vwfans.com
Subject: [Vwdiesel] Pump pressures, banjo jet sizes and injector leakage...

For more than a year I've had a diesel leak on the No1
injector. It looked  like it was one of the pressed in
return nipples leaking. On a really close inspection today I
found it was the replacement 'blanked off' pipe which was
made of some kind of plastic rather than 'rubber' AND a
slight leak on the steel injector supply pipe.
I removed this pipe and considered replacing it with a spare
2nd hand one. I decided that I'd try and reuse the existing
one.
Using a magnifying glass I looked at the belled end and was
amazed as to how rough the pipe was but importantly noticed
that on one side there was a ridge where the injector had
'dug in' probably due to successive over tightening to stop
leaks over the years. Using a honing stone I removed the
ridge  (being careful to avoid abrading the main mating
surface). This coupled with complete renewal of injector
fuel returns cured my leak :o)
Interestingly my previous encounter with this leak had led
me to believe that there was quite a lot of fuel returning
as when I had removed the pipe with the stopper the fuel had
spurted into the air...
 I was wrong; its less than a child trying to spit and the
fuel is actually coming from the pump via the banjo. The
hole leading to the injector pipes is between a 1/4 and an
1/8 of the area of the hole draining back to the tank. I'm
not sure if this back pressure is due to incorect return
pipe back to the tank as this vehicle is a replacement for
my engine and it was formerly a gasser. The pipe diameter is
approximately 1/4 inch polythene?

Moving on to Hagar's method of measuring pump pressure; I
dont see how it can be measured accurately (absolute
pressure) when its the removed banjo bolt that has the
metered bleed hole in it that creates the pressure in the
pump. Replacement with a drilled out bolt would change pump
pressure. Of course it could be used to compare pumps but
this wouldnt help those of us with only one pump unless the
'home kit' was passed around the members as required and the
data thus strengthened by cumulative readings....

Sorry for the long rant...
The Miser

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