Most of the operations described in this chapter are based on the fact that the engine has not yet been removed from the vehicle. Thus, if the information given here is used when an engine is overhauled or removed, many of the steps included in this chapter can be skipped.
Access to the engine compartment can be improved by removing the hood as described in chapter 11.
Engine description
In this chapter, engines are identified by manufacturer's letter code and by displacement. Engine identification is given in Specifications.
Engines - liquid-cooled, single or double camshaft, in-line four-cylinder with cast iron blocks and aluminum cylinder heads. All engines are mounted longitudinally in front. The gearbox is installed behind the engine.
The crankshaft is five-bearing, the support half-rings that determine the axial clearance are installed in the central support.
Camshaft - driven by a toothed belt from the crankshaft sprocket. ADR, APT, APW, AFY, AEB and AJL engines have two camshafts in the head, the exhaust camshaft is driven by a belt, the intake camshaft is driven from the exhaust by a chain installed at the rear ends of the shafts. The chain is tensioned by a hydraulic tensioner; in ADR, AFY and APT engines, the hydraulic tensioner plays the role of a regulator of the intake camshaft timing.
On ADP engines. ADR, AFY, APT and APW timing belt also drives the auxiliary shaft. from which, in turn, the oil pump and (on some models) distributor. The valves are driven from the camshaft cams by means of hydraulic pushers and the clearance in the drive is thus automatically adjusted.
The cylinder head has one or two camshafts driven by a toothed belt, intake and exhaust valves closed by one or two springs. The valve guides are pressed into the cylinder head. The camshafts act on the valves directly through hydraulic tappets, which are supplied with oil through drillings in the cylinder head.
All engines except AHL in the cooling system have a pump driven from the crankshaft by an auxiliary belt. On some models, the drive to the coca cooling system is carried out from the power steering pump pulley. On AHL engines, the coolant pump is driven by the timing belt. The cooling system is described in detail in chapter 3.
The engine is lubricated under pressure from a pump driven by a chain from the crankshaft (AHL) or from auxiliary shaft (ADP, ADR, APT, APW, AFY, AEB, AJL). The oil is taken by the pump from the sump through the oil receiver and fed into the replaceable oil filter. From there, under pressure, it is supplied to the cylinder head to the camshaft bearings and hydraulic pushers and to the engine crankcase, lubricating the crankshaft bearing journals, connecting rod journals, piston pins and cylinder walls. An emergency oil pressure sensor is screwed into the oil filter housing, which operates at a pressure of 1.4 bar. On AHL, APT, APW, AFY, AEB and AJL engines, an oil-cooling block is installed above the oil filter, which is flushed from the engine cooling system. used to reduce the temperature of the oil before supplying it to the cylinder block.
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