Table of contents: General information ↓ Preparatory operations ↓
General information
This chapter describes the most typical and important engine maintenance and repair procedures, with the exception of those requiring special skills and tools, such as engine overhaul procedures - these tasks should be entrusted to car service specialists.
The cars in question are equipped with 4-cylinder petrol engines with a capacity of 1.0, 1.2 or 1.4 liters. The engines have a DOHC design (with two overhead camshafts and two valves per cylinder).
But the piston contains 2 compression rings and one oil scraper ring.
The crankshaft is located in five main bearings.
The cylinder head is secured to the block with bolts.
Two camshafts are located in the cylinder head and drive the valves through rocker arms, fixed on tappets with hydraulic valve clearance compensators. The rocker arms transmit movement to the valves through rollers with needle bearings. The camshafts are driven from the crankshaft through a chain.
The oil pump is located in the front cover of the cylinder block and is driven directly from the crankshaft.
Components and diagram of the engine lubrication system
Preparatory operations
Before performing any engine maintenance procedures, clean the engine compartment and the outer 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 bonnet can be removed to provide free access to the components to be serviced (see Chapter Body). 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 the oil loss is not associated with the development of external leaks. Check the compression in the cylinders (see section Checking the compression pressure) to determine the general condition of the engine.
Loss of power, loss of RPM stability, excessive valve noise and increased fuel consumption are usually fairly common signs that an engine overhaul is needed, especially when all of these factors occur simultaneously. If performing a 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.
Major repairs of the power unit involve restoring all its operating parameters to the level typical of a new engine. During a major repair, piston rings are replaced and cylinder mirrors are restored (turning and/or honing). Usually, the main and connecting rod bearings of the crankshaft are replaced; if necessary, its journals can be turned and restored. Valve maintenance is mandatory; their condition at the time of the need for a major overhaul of the engine almost certainly leaves much to be desired. In parallel with the general overhaul of the power unit, a restorative overhaul of the starter and generator is usually also carried out.
Critical components of the cooling system such as hoses, drive belts 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 Vehicle settings and routine maintenance and Engine cooling, heating, ventilation and air conditioning systems). 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 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 mechanical workshop to perform certain repairs.
Most of the work can be done using a standard set of locksmith 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.
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 restoration repairs of worn components will be wasted if the requirement of maintaining cleanliness during assembly of the unit is neglected.