AnswerID: 24127 Submitted: Thursday, Jul 03, 2003 at 20:37
Martyn (WA)
replied:
Scott,
See if this is of any use to you it's not specific to the 1HZ motor more of a general thing, I found it in an engine tips
forum I'm a part of. From what I understand yes it could cause excessive oil consumption, but I would think you would see smoke, how much oil are you consuming, what's excessive? Can't help with the angle setting I'm not familiar with this, I thought that these valves where on petrol motors I've never seen mention of one on a diesel before, I could well be looking in the wrong place, maybe the Nissan motor is a tad more agricultural, the way I like it.....
The PCV Valve
by George Staley
When an engine is running, a tiny amount of the exploded gas-air mixture forces its way past the piston rings in a condition known as blow-by. These fumes would build up pressure in the crankcase and cause trouble if they were not allowed to escape. On old cars, a hollow pipe led from the top back of the engine and carried the fumes down under the car. This “draft tube” prevented gasses from building up in the engine but it also allowed the oily fumes to escape into the atmosphere.
Modern cars have many types of pollution control devices to protect the quality of our air. The system used to control crankcase fumes is called Positive Crankcase Ventilation or PCV. In this system, the “draft tube” leading from the crankcase is not vented to the ground but is routed to the intake manifold where the oily fumes are sucked into the engine along with the gas-air mixture and burned.
Most PCV systems enter the manifold below the carburetor. If this system is added to an older car, it is vital that a PCV valve be placed into the line carrying fumes from the crankcase. The function of the PCV valve is to regulate the flow of crankcase gasses as well as to prevent a “backfire” from the manifold, which could cause an explosion to travel down into the crankcase. The vacuum of the engine regulates the opening in the PCV valve. When engine vacuum is high, the flow of gasses is low. When engine vacuum is low as in rapid acceleration, the flow of crankcase gas is greatest.
Some systems use a dual setup in which the blow-by gas is sent to the air cleaner case as well as the intake manifold. When the dual system is used, it is common for the tube to the air cleaner to originate at a tappet cover or from the oil filler cap.
It is important that the size of the PCV valve be appropriate for the flow of fumes. PCV valves do come in many sizes so some research may be necessary to find the best after-market valve. The parts supplier may know the suitable size or he may be able to seek advice from the manufacturer.
It is important that you do not seal off the crankcase completely as a build up of fumes could cause engine problems.
Keep the shiny side up
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