There is provided an engine capable of reducing oil consumption. The engine includes a cylinder head, a cylinder head cover mounted above the cylinder head, a rocker arm covered by the cylinder head cover, and a breather chamber provided inside the cylinder head cover. As a front-rear direction is defined by a longitudinal direction of the cylinder head cover, the breather chamber has a blow-by gas inlet at one side in the front-rear direction, a blow-by gas outlet at another side in the front-rear direction, and an oil discharging guide chamber at an intermediate part in the front-rear direction. The blow-by gas inlet is opened on a bottom wall of the breather chamber, and a peripheral wall of the oil discharging guide chamber is protruded downwardly from the bottom wall of the breather chamber toward between the rocker arm provided at a side of the blow-by gas outlet and the blow-by gas inlet.

An oil and air separator includes a first housing including a central chamber therein, the central chamber divided into a first outer portion and a second inner portion by a barrier; a filter material disposed between the first outer portion and the second inner portion; a cap directly coupled to the first housing, the cap including a first lumen therethrough, the first lumen including a first end disposed at the second inner portion; an extension portion including a second lumen therethrough; and a coupler removably coupling the cap and the extension portion.

An improved blow-by gas return structure minimizes the occurrence of a drawback caused by freezing at a low temperature by bringing a state where freezing minimally occurs in a blow-bay gas passage such as a pipe disposed outside an engine. The blow-by gas return structure is configured such that a blow-by gas is introduced into an intake manifold through an inner passage formed in a head cover. The blow-by gas return structure includes an outer pipe which connects a blow-by gas outlet of the head cover and a blow-by gas inlet of a main pipe of the intake manifold in a communicable manner, and a temperature elevating mechanism configured to elevate a temperature of the blow-by gas inlet. The temperature elevating mechanism is configured such that a cooling water transfer passage is formed in a portion of the blow-by gas inlet of the main pipe.

An engine device including, in a cylinder block (6) thereof, a cylinder bore (73), a cam chamber (76) accommodating a camshaft (75), a push-rod chamber (78) accommodating a push-rod (77), and a tappet holder (80) configured to hold a tappet (79) in a slidable manner, the tappet (79) being configured to transmit the drive force from the camshaft (75) to the push-rod (77). The tappet holder (80) partitions the cam chamber (76) and the push-rod chamber (78). A bypass passage (83) communicating the cam chamber (76) with the push-rod chamber (78) is formed between the tappet holder (80) and the cylinder bore (73).

A breather chamber structure for an internal combustion engine wherein the breather chamber can be disposed compactly and the degree of freedom in the layout of the parts of the internal combustion engine can be raised. The breather chamber structure includes a crankcase, a cylinder body provided upwardly on the crankcase, and a breather chamber configured to separate oil from oil mist in the crankcase. The breather chamber includes a crankcase side breather chamber provided in the crankcase and open to a joining plane between the crankcase and the cylinder body, and a cylinder side breather chamber provided in the cylinder body and open to the joining plane.

An oil and air separator includes a first housing including a central chamber therein, the central chamber divided into a first outer portion and a second inner portion by a barrier; a filter material disposed between the first outer portion and the second inner portion; a cap directly coupled to the first housing, the cap including a first lumen therethrough, the first lumen including a first end disposed at the second inner portion; an extension portion including a second lumen therethrough; and a coupler removably coupling the cap and the extension portion.

An arrangement for removing blow-by gases from a crankcase of an internal combustion engine, the blow-by gases being able to be supplied to an air intake system via a tube device, the tube device being connected or connectable to a component assigned to the air intake system and to a component which is in fluid connection to the crankcase. The tube device including a blow-by conduit. The risk of a leaking or incorrectly mounted tube device is avoided in that the tube device has a diagnostic conduit, a spurious air flow being detectable via the diagnostic conduit when the tube device is not tightly connected or is not connected.

An engine including: an exhaust manifold (7) provided near one side surface of an engine; a turbocharger (60) having an exhaust-side inlet connected to the exhaust manifold; and a rocker-arm-chamber-integrated intake manifold (8) disposed on a cylinder head (5) and integrally including a rocker arm chamber (90) and an intake manifold (6). The intake manifold has a wall (101) dividing the rocker arm chamber provided near one side surface of the engine and the intake manifold provided near another side surface thereof to isolate the rocker arm chamber and the intake manifold from each other. The rocker arm chamber has, in its upper portion, a positive crankcase ventilation device protruding therefrom and returning blowby gas to an intake system. The positive crankcase ventilation device has a blowby-gas discharge port (67) connected with a gas conduit (68) through which blowby gas is delivered to an intake-side inlet of the turbocharger.

An internal combustion engine is provided with one or more oil drain-back passages. The oil drain-back passage include an entrance into a crankcase via a crankcase breathing window, the crankcase breathing window disposed within and through a bulkhead wall of the crankcase. Thus, each oil drain-back passage may be routed from a cylinder head of the engine to a crankcase breathing window where oil may then enter the crankcase and flow downward into an oil pan coupled to the crankcase.

A lubricating structure for a four-stroke engine includes a first oil groove and a second oil groove. The engine includes a crankcase, a cylinder, a cylinder head and an oil pan. The crankcase makes up a crank chamber. The cylinder head is equipped with a valve chamber housing valve driving mechanism. The oil pan is provided on a bottom of the crank chamber. The first oil groove leads mist of the lubricating oil in the crank chamber to the valve chamber by communicating the crank chamber and the valve chamber with each other. The second oil groove leads surplus lubricating oil in the valve chamber to the oil pan in the crank chamber by communicating a lower part of the valve chamber with a neighborhood of the oil pan in the crank chamber. The first oil groove is set smaller in flow path cross-sectional area than the second oil groove.