Air in fuel line (Pics)

[Kanzan]

Can't get rid of the air in the fuel line of my 81 Caddy diesel. Have tightened all connections, and replaced all the copper washers. The new engine seems to run quie well, except for the air in the line. Is this the correct filter? My filter mount has several deep scratches, but I think the filter casket should take of this, but maybe not. Where can I get a new filter mount? Thanks,  Kanzan

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[Pat Dolan]

Don't get obsessed with the air bubbles you see in the fuel line.  You probably don't have ANY leaks.

Where does it come from?  ALL liquids in atmosphere have gasses disolved and free within them.  Diesel is no exception.  The simple act of pumping or filtering will free SOME of the dissolved gasses into visible bubbles, but it takes a LOT of pressure to reach the miscibility point (hundred bar + for Nitrogen and Oxygen - better known as air - in most petroleum products).

This is one of the reasons your VE car has a needle lift sensor on #3.  Without it, there is no way to predict how many air bubbles are in the line (tiny they may be) and thus how much pump injection quantity is wasted compressing them back into solution (thus delaying timing and skewing injection quantity).  Basic reason why older diesels aren't all that accurate in timing, quantity and most of all - cleanliness.