Note: This chapter describes the most typical and important engine maintenance and repair procedures, excluding procedures that require special skills and tools (for example, a major engine overhaul), - these works should be entrusted to car service specialists.
The dependences of torque and power on the crankshaft speed of some gasoline engines are shown in figures 1.1a-b.
1.1a. Dependence of power (A) and torque (B) of the 1.2 l CBZB engine on the crankshaft speed
1.1b. Dependence of power (A) and torque (B) of a 1.8 l 118 kW (CDAA) diesel engine on the crankshaft speed
[Data Copied from the portal: skodabook.ru]
The engine code consists of four letters; the first three of them denote the mechanical design, and the fourth denotes the engine characteristics depending on its control unit. The engine serial number consists of six characters. If more than 999,999 engines are produced, the first digit in the number is replaced by a letter. The engine code is indicated on the vehicle data sticker and on the identification plate (see Introduction). The first three characters of the engine code and its serial number are also stamped above the place where it connects to the transmission (see illustration 1.2a). In addition, the engine code and its number are indicated on an additional sticker, which on the 1.2 l engine is located on the air pressure pipe (see illustration 1.2b), and on other engines - on the upper part of the timing belt cover (see illustrations 1.2c-e). To view the additional sticker on the 1.4L engine, release the EVAP canister hose from the holder or use a mirror.
1.2a. Engine code and number in the area of connection with the transmission (using the example of a 1.2 l engine)
1.2b. Sticker on the pressure pipe of the 1.2L engine
1.2s. Sticker on the timing belt cover of 1.4 l engines
1.2d. Code and number of engines 1.6 and 1.8 l, as well as 2.0 l (CBDB and CEGA)
1.2e. Code and number of engines 2.0 l (CFHA/CFHC/CFHF, CFJA, CLCB)
The engine is mounted transversely in the engine compartment located at the front of the vehicle. All engines are turbocharged and intercooled. The timing drive is carried out from the crankshaft: on petrol models - by a chain, and on diesel models - by a toothed belt.
The 1.2L engine block and cylinder head are made of aluminum alloy; sodium-filled intake valves are used.
The 1.4 and 1.8 l petrol engines have variable intake camshaft timing. The cylinder block of 1.8L engines is made of cast iron, and the cylinder head is made of aluminum alloy; additionally, an intake manifold with vortex flow damper control is used.
The Skoda Yeti is equipped with 2.0 diesel engines of three power levels (81, 103 and 125 kW). All variants have the same design, based on the 2.0 l TDI-CR power unit. The variants with different power outputs differ only in some minor design elements or control system settings. The CBDB and CEGA models belong to the so-called 1st generation of TDI-CR engines and were installed on Skoda Yeti cars only at the beginning of their production, after which they were replaced by the CFHC and CFJA models, respectively. All 2.0 l diesel engines have:
- cast iron cylinder block;
- aluminum alloy cylinder head;
- forged crankshaft with four counterweights;
- metal glow plugs;
- injection pressure up to 180 MPa;
- low temperature exhaust gas cooling;
- variable geometry turbocharger;
- injectors with 1MA value.
All 2.0L diesel engines do not have balance shafts. The 1st generation models use injectors with piezoelectric control valves and an intake manifold with swirl flap control. The 2nd generation models use injectors with electromagnetic control valves, a new characteristic of the exhaust gas pressure sensor and communication via the UDS diagnostic transport protocol; there is no fuel pressure check valve.
Due to the rarity of diesel models, a description of diesel engine repair is provided only for the most common of them (CFHC, CLJA and CLCB); for other diesel engines, only specifications and general maintenance procedures are provided. It should also be noted that a large number of works on diesel engines, not described in detail, are carried out similarly to the corresponding works described for CFHC, CLJA and CLCB engines.
Preparatory operations
Before performing any engine maintenance procedures, clean the engine compartment and 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 to be done, the hood can be removed to provide free access to the components to be serviced (see Chapter 11). To avoid accidental damage to the paintwork, cover the car fenders with special covers or old blankets.
Excessive engine oil consumption can be considered a signal that it is necessary 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 external leaks. Check the compression in the cylinders (see Section 2) to determine the general condition of the engine.
Loss of power, instability of revolutions, excessive noise of the valve mechanism and increased fuel consumption are usually quite characteristic signs of the need for a major engine overhaul, especially when all these factors appear simultaneously. If performing the full range of adjustments does not help to eliminate the problems, the only way out is to perform general mechanical work to restore the engine.
A major overhaul of a power unit involves restoring all of its operating parameters to the level typical of a new engine. During a major overhaul, piston rings are replaced and cylinder mirrors are restored (turning and/or honing). Typically, the main and connecting rod bearings of the crankshaft are replaced; if necessary, its journals can be turned and restored. It is mandatory to perform maintenance on valves, the condition of which at the time the need for a major overhaul of the engine almost certainly leaves much to be desired. In parallel with the general repair of the power unit, a restorative repair of the starter and generator is usually also carried out.
Note: Critical cooling system components such as hoses, drive belt and thermostat must be replaced with new ones during a major engine overhaul. In addition, the condition of the radiator should be carefully checked (see Chapters 1 and 3). If signs of leaks or obstruction are detected, the radiator should be replaced. Don't forget to check the condition of the oil pump as well. Major engine repairs do not require high professional training from the performer, but they do take quite a lot of time. You should plan to stop using the car for at least two weeks, especially if you need to seek help from a machine shop for the purpose of performing individual restoration work.
Most of the work can be done using a standard set of metalworking tools, but some of the tests 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 advisability of performing a major overhaul of the engine is the condition of its cylinder block. It is often cheaper and more reliable to replace a worn-out engine with a reconditioned one.
In conclusion, it can be noted that all efforts to perform refurbishment of worn components will be wasted if the requirement of cleanliness during engine assembly is neglected.