See Figure 1
The closed-type crankcase emission control system prevents blow-by gas from entering the atmosphere and keeps the internal crankcase pressure constant.
During engine operation, the blow-by gas is fed into the intake manifold by the crankcase emission control valve. When the intake air flow is restricted by the throttle chamber, the internal rocker cover pressure decreases. The valve keeps the engine pressure constant, so that air or dust is not sucked in around the crankshaft seals.
See Figures 2 and 3
Inspect the hoses; if necessary, use compressed air to unblock them. If the hoses are damaged or extremely dirty, replace them.
- Remove the crankcase emission control valve from the top of the rocker cover.
- Blow air from the rocker cover side of the valve, and make sure that air flows from the intake manifold side.
- Close the rocker cover side of the valve and suck on the pipe, to make sure that the diaphragm makes a clicking sound.
- If the valve does not perform as specified, replace the valve.