Vacuum Pump (Diesel Models Only) (Brakes)

Vacuum Pump (Diesel Models Only)

As the diesel engine air inlet system does not produce sufficient depression to operate the brake servo assembly, an engine driven vacuum pump is installed. The vacuum pump is attached to the LH end of the camshaft cover and driven at half engine speed by the exhaust camshaft. The pump is a rotary vane type, lubricated and cooled by engine oil supplied through a jet in the end of the exhaust camshaft. Air extracted from the brake servo is vented into the camshaft cover with returning lubricating oil.

Vacuum Pump Location

1 Alternator 2 Vacuum pump 3 Brake servo assembly vacuum connection

4 Oil feed pipe 5 Oil drain pipe

Vacuum Enhancer System (KV6 Only)

The vacuum enhancer system increases the relatively low vacuum available from the inlet manifold to increase braking assistance. The system consists of a venturi valve, a solenoid valve and associated pipes.

The venturi valve is installed in the vacuum pipe between the brake servo and the inlet manifold. An air feed pipe, from the intake duct upstream of the throttle body via the solenoid valve, is also connected to the venturi valve. Internal ducts in the venturi valve connect the brake servo and air feed ports to the inlet manifold port. The duct connecting the air feed port to the inlet manifold port incorporates the venturi. A check valve, integrated into the brake servo port, prevents the reverse flow of air and fuel vapour to the brake servo.

The solenoid valve controls the air feed to the venturi valve. Operation of the solenoid valve is controlled by the ECM.