A properly functioning Positive Crankcase Ventilation (PCV) system is critical to the life of your engine. It draws fresh, filtered air from the air filter (or Valve Cover Breather Filter, if installed) through the block in order to remove harmful gasses and moisture that builds up in the form of condensation as the engine cools down; moisture that would otherwise damage both internal components and the block itself over time. This system uses manifold vacuum to remove these harmful contaminants and sends them to the intake to burn with the fuel mixture. The PCV Valve is the main functional component of this system: its job is to regulate airflow through the system and prevent any sort of backflow into the block. Depending on how it failed, the valve can cause a few different symptoms, ranging from running lean/rich to excessive moisture in the oil. We recommend inspecting this valve at every tune-up and replacing as needed.
All 79-89 PCV Valves supercede to this valve.
PCV Valve Location:
The PCV Valve location varies slightly by model but is always mounted to a portion of the intake manifold assembly, on the manifold (smaller) end of the PCV hose (NOT on the larger end of the hose which attaches to the large diameter tube on the front driver's side of the block):
- 70-74 Carbureted Models: Located on the balance tube that mounts across the intake manifolds. It points out toward the carburetors from the center of the balance tube. The hose runs from the PCV tube on the lower left (driver's) side of the engine block (toward the front of the block), under the front intake manifold, then up to the valve.
- 75-83 Fuel Injected Models: Located on the underside of the intake manifold. It points down toward the ground and is roughly centered front to back (exact position varies based on your intake manifold). The hose runs from the PCV tube on the lower left (driver's) side of the engine block (toward the front of the block), under the front intake manifold, then up to the valve.
- 84-89 Fuel Injected Models: Located on the right (passenger) side of the intake collector. It points out toward the right side of the car and is roughly centered front to back. The hose runs from the passenger side valve cover up to the valve.
Datsun 240Z, 260Z, 280Z, 280ZX, 300ZX
Datsun S30, S130, Z31
1970, 1971, 1972, 1973, 1974, 1975, 1976, 1977, 1978, 1979, 1980, 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989