The cylinder bores are bored in the crankcase made of gray cast iron. With a lot of wear or risks on the cylinder walls, they can be honed at the service station. After honing, pistons of increased diameter should be installed in the cylinders. At the bottom of the crankcase is a crankshaft mounted in bearings. The connecting rods connecting the pistons to the crankshaft are mounted on the crankshaft with plain bearings The lower part of the engine closes the oil pan, which contains the engine oil necessary for lubrication and cooling The cylinder head is bolted to the crankcase from above Depending on the engine, the cylinder head is made of gray cast iron or light (aluminum) alloy.
The cylinder heads of gasoline engines are made according to the so-called principle of organizing the transverse movement of the charge. This means that a fresh fuel-air mixture is supplied to the cylinder head from one side, and exhaust gases are removed from it from the other side. Due to the transverse movement of the gas flow through the intake and exhaust valves, a quick change of charge in the cylinders is carried out.
For a 4-cylinder ONS engine (Over Head Camshaft) the camshaft is on top (located in the cylinder head). The camshaft is driven from the crankshaft by a toothed belt. The camshaft drives the valves through push levers.
For a 4-cylinder DOHC engine (Double Over Head Camshaft) The cylinder head has 2 camshafts. One camshaft controls the intake valves and the other controls the exhaust. Camshafts driven from the crankshaft by a common chain act on the valves through hydraulic tappets.
The 6-cylinder V-twin engine has a single central camshaft that drives the intake and exhaust valves through tappets and rocker arms. The camshaft is driven by a chain, and for an engine with a displacement of 2.8 liters, through gears.
6-cylinder V-twin engine with a displacement of 2.9 liters has 4 camshafts In each cylinder block, one camshaft controls the intake valves and the other the exhaust valves. The camshafts are driven by a chain.
For diesel engines, the camshaft is located on the side of the cylinder block. It drives the intake and exhaust valves through tappets and rocker arms. The camshaft is driven by a chain. Due to lack of space, the intake and exhaust manifolds are located on the same side of the cylinder head.
Engine lubrication is provided by an oil pump located in the oil pan and driven from the camshaft through the auxiliary shaft. The oil taken from the oil pan is supplied through bores and channels to the bearings of the crankshaft and camshaft, as well as to the working surfaces of the cylinders.
The coolant pump is located at the front of the crankcase and is driven by a V-belt or V-ribbed belt, which also drives the alternator. Some models have a cooling fan on the coolant pump shaft, which, at a certain coolant temperature, is turned on through a viscous coupling. It is necessary to ensure that the cooling system is filled all year round with a mixture of soft water with antifreeze and anti-corrosion additives.
To prepare and ignite the air-fuel mixture, gasoline engines have a carburetor or a maintenance-free electronically controlled fuel injection system.
The ignition spark in a gasoline engine is produced by a maintenance-free electronic ignition system.
Safety note: Switch off the ignition before working in the engine compartment. The cooling fan may turn on automatically. which is caused by heat build-up in the engine compartment. Risk of injury due to V-belt and fan blades!
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