Vent hole on the crankcase

When the Cummins Diesel engine is working, there will always be some combustible gas and exhaust gas entering the crankcase through the gap between the piston ring and the cylinder wall. Condensation of fuel vapor entering the crankcase will dilute the oil, and the acidic substances and water vapor in the exhaust gas will corrode parts and deteriorate the performance of the oil (dilution, aging and coking). In addition, the gas entering the crankcase will increase the temperature and pressure in the box, causing oil to seep from the oil seal, gasket, etc.; due to the reciprocating motion of the piston, the gas pressure in the crankcase changes periodically, affecting The normal operation of the engine will cause the engine oil in the crankcase to escape to the combustion chamber and cylinder head cover when it is serious. Appear to avoid above-mentioned various phenomena, ventilating device is set on engine, with balancing crankcase inside and outside air pressure.

In case of engine oil burning, oil leakage along the joint surface, premature deterioration of the engine oil, and unstable idling of the engine, etc., check whether the crankcase ventilation device is effective; ensure that the vent hole is unblocked, and the negative pressure valve plate must not be deformed. Adhesion or wrong installation, the breathing tube must not be bent or blocked, the one-way valve must not be installed backwards, and the fuel plug must not be replaced by a wooden plug.

6. The dust discharge hole on the dust cover of the air filter

Some engines do not have a dust cup on the dust cover of the air filter (such as 4115, 2125 and 195 diesel engines), but have two tangential dust discharge holes on the dust cover opposite to the direction of airflow rotation , so that you can rely on inertia to filter while removing dust. If the dust discharge hole is blocked, the dust cannot be discharged in time, and it will also affect the filtration of other particles, thereby increasing the air intake resistance, and causing the engine to fail due to insufficient air supply and power drop.

7. Spray holes for cooling the back of the top of the piston by spraying oil

For the pistons of certain high-strength diesel engines, the conventional cooling can no longer meet the requirements, so the structural measure of cooling the top of the piston with oil injection is adopted. Among them, the most widely used one is to lubricate lubricating oil through the oil channel in the center of the connecting rod through the spray hole set at the top of the small head of the connecting rod to spray oil on the back of the piston top (such as 6120Q type, Mitsubishi DC type diesel engine); Some models have special nozzles at the lubricating oil passage to spray oil on the top and back of the piston for cooling (such as 6140 type, Nissan RD8 type diesel engine).