Quote:
Originally Posted by mrad01
The check valve maintains an oil supply in the VANOS transmission and oil circuits after the engine is turned off. This prevents the possibility of piston movement (noise) within the VANOS transmission system on the next engine start."
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Thanks, but I wanted to know where exactly the valves are, and where they get the oil from. By the way, there's no 'pistons' on VANOS.
And to throw you off, take a look at this info from a technical BMW document:
At zero pressure, a locking pin (2) also holds
the VANOS unit in the normal position or
engine start position.
That means even with no oil in the system, it's locked in its 'normal positon'. So the noise might be from something else 
.
It has pictures, but no pictures of the actual valves, or where they get oil from. This is what I could copy from the document, for your reading pleasure (pics didn't copy) 
:
VANOS
The compact double VANOS system fitted to
the S65 engine operates at normal oil
pressure, unlike the S85 engine (which uses
high oil pressure). The low-pressure system
means that the high-pressure pump and
additional pressure lines and reservoir are
unnecessary. This results in a space saving as
well as a weight reduction of approx. 8.4 kg.
This has been made possible by the
considerably stronger switching moments at
the camshaft compared to the 10-cylinder and
6-cylinder engine, particularly in the lower
engine speed range. The low-pressure
system uses these switching moments to
adjust the overall gear ratio.
The oil is directed to the sealed oil chambers
(3 and 4) of the VANOS adjustment unit.
When the chambers are pressurized with oil
pressure, one chamber allows the camshaft to
advance whilst the other chamber allows the
camshaft to retard.
The VANOS oil pressure is supplied by the
engine’s main oil pump. The VANOS oil flow is
controlled by one multiway valve for each
camshaft. These VANOS multiway valves are
controlled by the MSS60 and are directly
installed in the cylinder head.
41 - S65B40 VANOS hydraulic motor
Index Explanation
1 Optimized hydraulic rotor pressure
surfaces
2 Optimized inlet channel
oil chamber 1
3 Oil chamber 1
4 Oil chamber 2
5 Optimized inlet channel
oil chamber 2
42 - S65B40 VANOS Hydraulic schematic of a cylinder bank
Index Explanation
1 Oil supply from the main oil
gallery
2 Non-return valves
3 Sieve filter upstream from
control valves
4 Hydraulic motor at the inlet and
exhaust camshaft
5 Multiway adjustment valves inlet
and exhaust side
6 Oil return flange to the oil sump
51
8
As with the S85, the VANOS adjustment unit
of the inlet camshaft drives the VANOS
adjustment unit of the exhaust camshaft by
means of a constantly meshed gear.
At zero pressure, a locking pin (2) also holds
the VANOS unit in the normal position or
engine start position.
The spiral-wound spring (3) is also used for
coordinating the adjustment time between the
advance and retard adjustment.
In contrast to AG petrol engines, the spiralwound
spring for the inlet and exhaust sides is
mounted in the opposite working direction,
since the camshafts in the S65 rotate in the
opposite direction.
The principle of action of the hydraulic motor
in this M VANOS is based on the VANOS in
current BMW petrol engines and is optimized
for the S65 in terms of oil supply and drainage
diameters, and in the rotor surface area.