[Vwdiesel] '00 Golf IP pump seal problem

[lbaird119 at aol.com]

 Except that the bubbles are in the suction line, prior to entering the pump.  Sure, 
a vacuum will do (is essentially) the same thing as you described, there hopefully, 
isn't enough vacuum in the supply line or else the pump won't pump well and there's 
probably a restriction in the line.  
  In my experience, those bubbles come from leaking fittings/connections.  On the 
Rabbits, it's the hard line to rubber line, behind the fuel filter or the line itself, at the 
fuel tank.  On both Passats, it's been the thermo control on the fuel filter or the crimp 
fittings on the clear line itself.  Leaks between the crimp and the crimps and the hose.
     Loren





-----Original Message-----
From: pmdolan <pmdolan at sasktel.net>
To: vwdiesel <vwdiesel at vwfans.com>; Stephen Sherman <spsherm at msn.com>
Sent: Tue, Sep 6, 2011 4:41 am
Subject: Re: [Vwdiesel] '00 Golf IP pump seal problem


It is not likely that you have any air leaks.  ALL liquids stored in 
tmosphere have a tremendous amount of air dissolved within.  When you 
ut fuel through pumps, fittings, etc. where the flow must cross or be 
orced around very sharp edges, the resulting low pressure releases 
ome of that dissolved air, and that is what you will ALWAYS see in the 
lear lines of VW diesels.  Think about pictures of submsarines or 
ven props on regular surface vessels - they always have a trail of 
ubbles coming from them. That is dissolved air being released from air 
and why it is so difficult to make a submarine quite - when those 
ubbles implode them make a very loud noise that is easily detected by 
onar - and that same implosion is so violent it blows little bits of 
etal off of propellors and impeller - called cavitation wear. I could 
rite a book about which diesel engine designs don't work as intended 
ecause they don't deal with dissolved air properly/  And, yes, in 
ase you are wondering, this is one of the things I do for a living - 
ake equipment to remove dissolved air from oil). 
On Mon, 5 Sep 2011 21:22:56 -0600, Stephen Sherman  wrote:
ell a bit more as things unfolded... 

 Car drove well for a week, then one day I noticed a strong fuel 
 smell. Looked under the hood, and the IP was leaking from the seal 
 below the QA. Pretty obviously that gasket from the wet area and 
 dirt.  Order the gasket kit and special tool, and replaced that and 
 the top cover gasket. Got the QA adjustment back into the working 
 range (good idle now), and things seem OK. At least no signs of new 
 fuel leaks around the IP.  Definitely would suggest multiple 
 alignment marks if you do this, as I needed to rely on a second set 
 to get the QA in spec. (The epoxy chipped off as I took it apart, so 
 wasn't able to use those marks)

 Still have some air leak, as I can occasionally see a stream of 
 bubbles in the fuel clear line. Hoping its not one of the IP gaskets 
 I replace. Will replace the injectors furl return line as it is 
 getting pretty old. And take a closer look at the main return and 
 fuel lines. But at this point, the only symptom is the air bubbles in 
 the fuel line. No obvious leaks anywhere. 


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