921521-6616 Nissan SCREW

Hot engine components can cause injury from burns. Before performing maintenance on the engine, allow the engine and the components to cool.
Making contact with a running engine can cause burns from hot parts and can cause injury from rotating parts.When working on an engine that is running, avoid contact with hot parts and rotating parts.
Inspect the engine air cleaner inlet and ducting in order to ensure that the passageway is not blocked or collapsed.
Inspect the engine air cleaner element. Replace a dirty engine air cleaner element with a clean engine air cleaner element. Refer to Operation and Maintenance Manual, "Engine Air Cleaner Element (Dual Element) - Clean/Replace" or Operation and Maintenance Manual, "Engine Air Cleaner Element (Single Element) - Replace" for the correct procedure.
Check for dirt tracks on the clean side of the engine air cleaner element. If dirt tracks are observed, contaminants are flowing past the engine air cleaner element and/or the seal for the engine air cleaner element. Inspection of the Crankcase Breather
There may be a filter for the crankcase breather installed on the engine. If the filter for the crankcase breather becomes blocked, the pressure relief valve will operate. The pressure relief valve will also operate if there is a blockage in the system.A general visual inspection should be made of the crankcase breather. To indicate that the pressure relief valve for the crankcase breather has been in operation, the following issues will be seen. These issues are found behind the breather canister (if equipped).
Smearing of the oil
Droplets of oil
Wet patches of oil
Check the element for the engine crankcase breather (if equipped). If necessary, replace the element for the crankcase breather. Refer to Operation and Maintenance Manual, "Engine Crankcase Breather Element - Replace".
If there is sludge or debris in the canister, remove the canister (if equipped). Refer to Disassembly and Assembly, "Crankcase Breather - Remove and Install". Clean the inside of the canister (if equipped). Check that the gas inlet, the outlet connections, and the connections for the oil drain are clear.
Remove the breather hoses and visually check the insides for signs of blockage and check with low-pressure air. If necessary, clean the hoses.
If necessary, replace the element for the crankcase breather (if equipped). Refer to Operation and Maintenance Manual, "Engine Crankcase Breather Element - Replace".
Install the canister (if equipped) and hoses. Refer to Disassembly and Assembly, "Crankcase Breather - Remove and Install".
Check that the outlet for the crankcase breather is clean and free of obstructions. Ice can cause an obstruction in adverse weather conditions. If excessive crankcase pressure is experienced and the pressure relief valve for the crankcase breather has not activated, there could be a blockage in the valve mechanism cover.
Remove the valve mechanism cover. Refer to Disassembly and Assembly, "Valve Mechanism Cover - Remove and Install" for the correct procedure.
Inspect the inside of the valve cover for debris. The separator for the oil in the cover must be inspected. Ensure that all debris is removed from the cover. Note: Do not attempt to remove the separator from the cover. The separator can be cleaned if the separator is still attached to the cover.