[Vwdiesel] '00 Golf IP pump seal problem

[pmdolan at sasktel.net]

It is not likely that you have any air leaks.  ALL liquids stored in 
atmosphere have a tremendous amount of air dissolved within.  When you 
put fuel through pumps, fittings, etc. where the flow must cross or be 
forced around very sharp edges, the resulting low pressure releases 
some of that dissolved air, and that is what you will ALWAYS see in the 
clear lines of VW diesels.  Think about pictures of submsarines or 
even props on regular surface vessels - they always have a trail of 
bubbles coming from them. That is dissolved air being released from air 
(and why it is so difficult to make a submarine quite - when those 
bubbles implode them make a very loud noise that is easily detected by 
sonar - and that same implosion is so violent it blows little bits of 
metal off of propellors and impeller - called cavitation wear. I could 
write a book about which diesel engine designs don't work as intended 
because they don't deal with dissolved air properly/  And, yes, in 
case you are wondering, this is one of the things I do for a living - 
make equipment to remove dissolved air from oil). 

On Mon, 5 Sep 2011 21:22:56 -0600, Stephen Sherman  wrote:
Well 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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