Just thought I'd pass on the results of 3 weeks of head scratching trying to
solve an air leak in the fuel system on my 605 SVDT.  Poor running and
starting became steadily worse over a period of a couple of months.  I found
that bleeding air out of the fuel filter head cured the poor starting but
the poor running remained a problem.  Using a length of clear plastic hose,
I eventually traced the air leak to the fuel heater mounted on the end of
the head (water heated I assume).  At a steady 2000 revs a steam of bubbles
could be seen being sucked along to the fuel injection pump, how air was
entering this cast heater I have no idea.  This heater is now by-passed and
the problem has gone.  The question is does the engine need this heater
these days now that the wax level in diesel fuel is so much lower than it
once was?  Anyone know?

Regards Mike