The description of most of the procedures under consideration is based on the assumption that the power unit remains in its regular place in the engine compartment of the car. In view of the above, if the engine has already been removed and installed on a workbench or mounting stand, many of the described steps should be omitted.
Note that despite the physical possibility of in situ repair of components such as connecting rod and piston assemblies, this kind of work is usually carried out after disassembling the engine due to the need for some auxiliary procedures, not to mention the requirements for maintaining the cleanliness of parts and absolute patency of oil flows.
General description of the engine
The engine in question belongs to the family of 4-cylinder diesel engines with an in-line arrangement of cylinders, an overhead camshaft (OHC) and water cooling. The engine is mounted transversely at the front of the vehicle and tilted forward at an angle of 14°. The transmission and clutch assemblies are located on the left side of the power unit.
A camshaft is installed inside the cylinder head, which is driven by a toothed belt drive from the crankshaft. Inlet and outlet valves are planted in the guide bushings pressed into the body of the head. Closing of each of the valves occurs due to the force developed by a single helical spring. The camshaft cams act on the valves directly through hydraulic tappets planted in individual sockets. The oil supply to the hydraulic compensators and for lubrication of the pushers is carried out through the oil flows cast in the body of the head.
Skoda Felicia vehicles are equipped with diesel engines with indirect fuel injection - replaceable swirl chambers are mounted in the cylinder head.
The crankshaft is mounted in five main bearings. The bearing installed between the second and third cylinders is thrust and controls the axial play of the shaft.
The intermediate shaft driven by the timing belt ensures the operation of the vacuum pump of the brake booster and the oil pump of the engine lubrication system.
Coolant circulation is provided by a water pump driven by an auxiliary belt. Details on the principle of operation of the cooling system can be gleaned from the materials of Chapter Cooling, heating systems.
The forced lubrication system of the engine is organized by means of a pump driven directly from the intermediate shaft. The intake of oil from the oil pan is carried out through an oil intake equipped with a strainer. Before entering the engine lubrication circuit, the oil is forced through an externally mounted, full-flow, replaceable type oil filter. After passing through the filter, the oil enters the cylinder head, where it is used to lubricate the camshaft bearing journals and hydraulic valve lifters, and then to the engine crankcase, to the main and connecting rod bearings, piston pins and cylinder mirrors. Atomizers are mounted at the base of each of the cylinders, providing oil supply to the under-piston space in order to increase the efficiency of heat removal. The oil cooler included in the cooling system path lowers the oil temperature before it is fed into the engine.
The engine arrives at the Skoda plant without attachments (in addition to the equipment of the power supply system) and already on the conveyor it is completed with a generator, water and steering pumps. Auxiliary units are driven by a belt drive.
List of repair procedures that do not require removing the engine from the vehicle
The following are engine repair and maintenance procedures that can be performed in situ:
- a) Removal and installation of the auxiliary drive belt;
- b) Removal and installation of a camshaft;
- c) Replacing the camshaft seal;
- d) Removal and installation of the camshaft gear;
- e) Removal and installation of the water pump (see chapter Cooling, heating systems);
- f) Replacement of crankshaft seals;
- g) Removal and installation of the crankshaft gear;
- h) Removal and installation of the cylinder head;
- i) Checking the condition and replacing the suspension mounts of the power unit;
- j) Replacing the intermediate shaft seal;
- k) Removal and installation of the oil pump and oil intake assembly;
- l) Removal and installation of the oil pan;
- m) Removing, checking the condition and installing the timing belt with gears and front cover.