[Vwdiesel] cold start shaft reseal in car Re: pump still leaks

[Andrew .Libby]

The pumps with the elctronic component on the front and block-off plate on
the back are most often direct injection engines which do not require any
advance for easy cold starting.  If a timing advance is fitted it acts on
the dynamic advance piston.  The dynamic piston adjusts timing according to
rpm and is governed by the difference in pressure between the pump inlet and
the internal pressure of the pump.  The internal pressure is a function of
rpm due to the vane pump pumping more and the fact that the pump outlet is a
very small specifically sized orifice which resists the flow of diesel out
of the pump.  As Loren mentioned, the electric solenoid is most often a
device to retard timing under some engine conditions by opening a port which
normalizes the pressure on either side of the advance piston.

Andrew

On Thu, Sep 17, 2009 at 8:04 AM, brian gochnauer <brian at gochnauer.net>wrote:

> From the pics I've seen the 'electrical component on the front' is the
> electric version of a lever that would be the backside. When the there's an
> electric solenoid on the front the lever port on the back is blocked off.
>
>