Note: This chapter describes the most common and important engine maintenance and repair procedures, excluding procedures requiring special skills and tools (e.g. engine overhaul), - these works should be entrusted to car service specialists.
Dependences of torque and power on the crankshaft speed of some gasoline engines are shown in illustrations 1.1a-c.
1.1a Power dependence (A) and torque (IN) engine 1.4 l SAHS from the crankshaft speed
1.1b Power dependency (A) and torque (IN) engines 1.8 l BZB and CDAA on the speed of the crankshaft
1.1s Power dependency (A) and torque (IN) engine 3.6 l CDVA from crankshaft speed
The engine code consists of four letters; the first three of them mean the mechanical design, and the fourth one means the characteristics of the engine, depending on its control unit. The serial number of the engine consists of six characters. If more than 999,999 engines have been produced, the first digit in the number is replaced by a letter. The engine code is on the vehicle data sticker and on the identification sticker (see Introduction). The first three characters of the engine code and its serial number are also stamped on the cylinder block above its junction with the transmission (see illustrations 1.2a-b) or on a 3.6L engine, above the crankshaft pulley (see illustration 1.2c). In addition, the engine code and number are indicated on an additional sticker, which is located on the intake manifold on the 3.6L engine, and on the top of the timing cover on other engines (see illustrations 1.2d). To see the additional sticker on the 1.4L engine, release the EVAP canister hose from the holder, or use a mirror.
1.2a Code and number of the engine in the area of connection with the transmission (BZB, BXE, BLS, CDAA/CDAB and CAYC engines)
1.2b Engine code and number in the transmission connection area (motors BMP, BKD, SVVV, CFFB, CLJA, CFGB)
1.2s Engine code and number next to the CDVA engine pulley
1.2d Sticker on the timing case of the 1.4L engine
The engine is mounted transversely in the engine compartment located at the front of the vehicle. All engines, except for the 3.6 liter petrol, are turbocharged, with an intercooler. The timing drive is carried out from the crankshaft: on gasoline models - by a chain, and on diesel models - by a toothed belt.
The cylinder block of gasoline engines is made of cast iron. The 1.4, 1.8 and 2.0 liter engines have an intake camshaft timing adjustment, and the 3.6 liter engine also has an exhaust camshaft adjustment. On 1.8 and 2.0 liter engines, the following are additionally used: an intake manifold with a controlled swirl damper and balancer shafts in the cylinder block. The 3.6 liter engine uses internal exhaust gas recirculation and a 2-piece variable geometry plastic intake pipe.
Diesel engines of various designs can be installed: 1.9 and 2.0 l with unit injectors (TDI-PD), 2.0L with fuel rail (TDI-CR) 1st generation and 1.6/2.0L TDI-CR 2nd generation. Due to the rarity of diesel models, a description of the repair of diesel engines is given only for the most common of them: 1.9 TDI-PD (WHE and BLS) and 2.0 TDI-CR 2nd generation (CFFB, CLJA and CFGB). For other diesel engines, only specifications and general maintenance procedures are given. It should also be noted that a large number of work on diesel engines, not described in detail, is performed in a similar way to the corresponding work performed on the engines described.
Preparatory operations
Before carrying out any engine maintenance procedures, clean the engine compartment and the external surfaces of the power unit using a special solvent. This treatment will prevent dirt from getting inside the engine.
If necessary, depending on the nature of the work ahead, the hood can be removed in order to provide freedom of access to the components to be serviced (see chapter 11). To prevent accidental damage to the paintwork, cover the fenders of the car with special covers or old blankets.
Excessive consumption of engine oil can be considered a signal to check the condition of the piston rings, valve stem seals and / or valve guides. Naturally, first of all, you should make sure that oil losses are not associated with the development of its external leaks. Check cylinder compression (see section 2), to determine the general condition of the engine.
Loss of power, rev stability, excessive valve train noise, and increased fuel consumption are usually fairly common signs that an engine needs an engine overhaul, especially when all of these factors occur at the same time. If performing a full range of adjustments does not resolve the issue, the only recourse is to perform a general mechanical rebuild on the engine.
The overhaul of the power unit involves the restoration of all its operating parameters to the level characteristic of the new engine. During the overhaul, it is mandatory to replace the piston rings and restore the cylinder mirrors (turning and/or honing). Usually, the main and connecting rod bearings of the crankshaft are replaced, if necessary, turning and restoring its necks can be made. It is mandatory to service the valves, the condition of which at the time of the need for an overhaul of the engine almost certainly leaves much to be desired. In parallel with the general repair of the power unit, reconditioning of the starter and generator is also usually carried out.
Note: Critical cooling system components such as hoses, drive belt and thermostat must be replaced with new components during engine overhauls. In addition, you should carefully check the condition of the radiator (see Chapters 1 and 3). If there are signs of leaks or obstruction, the radiator should be replaced. Don't forget to check the condition of the oil pump as well.
Overhaul of the engine does not require high professional training from the performer, but it takes a lot of time. You should plan to stop using the car for at least two weeks, especially if you need help from a mechanic shop to carry out some restoration work.
Most of the work can be done with the usual set of hand tools, however some of the checks to determine the suitability of individual components for further use require the use of precision measuring equipment. In doubtful situations, seek help from service station specialists.
Note: Do not forget that the decisive factor in the question of the expediency of overhauling the engine is the condition of its cylinder block. It is often cheaper and more reliable to replace a worn engine with a remanufactured one.
All removable electrical wiring ties and clamps must be installed in their original places during installation. Wiring and hoses should be laid in the same way as they were located before removal. Therefore, you should memorize or sketch / photograph the location of clamps, electrical wiring and hoses.
In conclusion, it can be seen that all efforts to carry out reconditioning of worn components will be wasted if careless attention is paid to the requirement of cleanliness during engine assembly.