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Positive Crankcase Ventilation (PCV) system - general information
Emissions control systems / Positive Crankcase Ventilation (PCV) system - general information

General information
1 The crankcase ventilation system main components are the oil separator mounted on the front (radiator) side of the cylinder block/crankcase, and the Positive Crankcase Ventilation (PCV) valve set in a rubber grommet in the separatorТs left-hand upper end. The associated pipework consists of a crankcase breather pipe and two flexible hoses connecting the PCV valve to a union on the left-hand end of the inlet manifold, and a crankcase breather hose connecting the cylinder head cover to the air cleaner assembly (see illustration). A small foam filter in the air cleaner prevents dirt from being drawn directly into the engine.

8.1 Positive Crankcase Ventilation system
8.1 Positive Crankcase Ventilation system

1 Oil separator
2 Gasket
3 Positive Crankcase Ventilation (PCV) valve 4 Cylinder block/crankcase opening 5 Crankcase breather pipe and flexible hoses

2 The function of these components is to reduce the emission of unburned hydrocarbons from the crankcase, and to minimise the formation of oil sludge. By ensuring that a depression is created in the crankcase under most operating conditions, particularly at idle, and by positively inducing fresh air into the system, the oil vapours and Уblow-byФ gases collected in the crankcase are drawn from the crankcase, through the oil separator, into the inlet tract, to be burned by the engine during normal combustion.

3 Checking procedures for the system components are included in Chapter 1.

Component renewal
Cylinder head-to-air cleaner hose 4 See Chapter 1.

Positive Crankcase Ventilation (PCV) valve
5 The valve is plugged into the oil separator.

Depending on the tools available, access to the valve may be possible once the pulse-air assembly has been removed (see Section 7).

If this is not feasible, proceed as outlined in paragraph 6 below.

Oil separator
6 Remove the exhaust manifold (see Chapter 2, Part A). The Positive Crankcase Ventilation (PCV) valve can now be unplugged and flushed, or renewed, as required, as described in Chapter 1.

7 Unbolt the oil separator from the cylinder block/crankcase, and withdraw it; remove and discard the gasket.

8 Flush out or renew the oil separator, as required (see Chapter 1).

9 On reassembly, fit a new gasket, and tighten the fasteners to the torque wrench settings given in the Specifications Section of Chapter 2, Part B.

10 The remainder of the refitting procedure is the reverse of removal. Refill the cooling system (see Chapter 1). Run the engine, check for exhaust leaks, and check the coolant level when it is fully warmed-up.

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