Revision as of 07:29, 7 January 2013

Positive Crankcase Ventilation (PCV) was the very first of the emission controls. It aims to prevent the crankcase from dumping fumes right into the atmosphere. This is a good system, and can actually help power and fuel economy. Before 1964, cars had a 'breather pipe' that led from the block down to the underside of the car. Normal blowby gases were thus simply vented to the air. Worse yet, when the piston rings became worn, a visible trail of smoke could be seen eminating from the bottom of the car. Not only did it pollute, but didn't smell good either.

1 Overview
2 CAUTIONS
3 Operation
4 Interchange
- 4.1 Part Numbers

Overview

The PCV system consists of three components:

Simple vacuum-operated valve connected to the intake manifold
crankcase breather hoses:
- from engine block to the PCV valve
- from rocker cover to the air cleaner

Upper breather hose connects to bottom side of air cleaner

Lower breather hose

The PCV Valve threads into the intake manifold

Black (lower) hose is the main PCV hose. On the manifold end it connects to the PCV valve. The other end goes to the engine block breather pipe.

Race cars are often required to use an oil/vapor seperator instead of, or in addition to, the PCV valve. The main purpose of this racing requirement is not to increase performance, but to control oil spills onto the race track surface.

CAUTIONS

As part of your Tune-up, replace the PCV valve if it:

oil-soaked or crusted with sludge (sometimes it can be cleaned with ether spray or carb cleaner). The valve inside should open and close when you shake it back and forth
Has a broken spring. The valve inside should close at rest, even if you hold it straight

NOTE: A stuck PCV valve is a vacuum leak (if stuck open).

Operation

Nissan calls its PVC system the "Crankcase Emission Control System", as it cleans up emissions with no loss of power. PCV system is a good thing.

Fumes are thus routed to either 1) air cleaner when engine speeds are high and so able to 'suck' the fumes in or 2) intake manifold when idling where vacuum is high and so opens the valve slightly and pulls the fumes out of the crankcase. This is where the efficiency comes in. Since at idle the pistons are operating under low vacuum, the PCV valve equalizes the forces in the crankcase, hence less oil is sucked into the cylinders at idle.

PCV system

Datsun 1200 GX engines routed the hoses in a different manner. See A12GX Engine.

Also see:
Engine_block#Ventilation
Breather Tubes

Interchange

Same as all Datsun (L/A/VG/U/R/CA/Z/E/J), many Nissan (including GA) and Subaru 1998-2002 2.5.

Part Numbers

11810-A3500 ASSY-CONTROL VALVE CRANK CASE EMISSIO A12

1.64 in. height
0.69 in. outlet
0.75 in. O.D.
NPTF thread pitch
* Purolator PV1019
** Purolator PV1016 has same dimensions but flow differs

Aftermarket buy at Rockauto.com
* FRAM FV263 
* Standard Motor Products V184T or V184 $2.19
* Beck/Arnley 0450031
* Airtex 6P1056 or PCV2 $2.93
* AcDelco CV1016C or 25173530

PCV Valve, from $2.00 - $7.50. Available everywhere

PCV Valve: FRAM FV263 $1.73, BECK/ARNLEY 0450031 $2.24

Infiniti 1993-1997 J30
Subaru 1998-2002 FORESTER 2002 IMPREZA
1971-1973 1200
1972-1979 620 PICKUP 
1966-1970 1600
1974-1977 710 
1968-1970 2000 
1980      720 PICKUP
1977-1986 200SX
1983-1986 720 PICKUP
1979-1982 210
1977-1981 810
1970-1973 240Z 
1974-1978 B210
1975-1977 280Z 
1986-1989 D21 PICKUP
1979      280ZX 
1976-1978 F10 
1990-1996 300ZX
1982-1984 MAXIMA
1979-1982 310
1987-1989 PATHFINDER
1967      411
1983      PULSAR 
1968-1973 510
1983-1990 PULSAR NX
1978-1981 510
1982-1990 SENTRA
1965-1968 520 PICKUP
1982-1986 STANZA
1969-1972 521 PICKUP
1988      VAN 
1973-1976 610

FRAM FV263 interchange
* Nissan 
  11810-30P00/11810-40P00
  11810-80W00
  11810-A3500/11810-A3501
  11810-E3000
* AC-Delco CV941C

Nissan 11810-A3500 <2> 11810-A3501
* 1983-1983 B11 with E15S/E16S engine 
* 1979-1981 N10 with A14S/A15S engine
* 1983      N12 with E16S engine

Nissan 11810-A3501
* 1982-1988 B11 with E15S/E16S
* 1988-     B12 with GA16I
* 1986-1988 B12 with E16S/E16I
* 1989-     KN13 with GA16
* 1987-1988 KN13 with E16
* 1988-1989 KN13 with CA18D
* 1987      KN13 with CA16D
* 1983-     N12 with E16S

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PCV