Most of the procedures discussed herein are written on the assumption that the powertrain remains in its original location in the engine compartment of the vehicle. As such, if the engine has already been removed and installed on a workbench or assembly stand, many of the steps described herein should be omitted.
It should be noted that despite the physical possibility of performing in situ repairs of components such as connecting rod and piston assemblies, this type of work is usually performed after disassembling the engine due to the need to carry out some auxiliary procedures, not to mention the requirements for maintaining the cleanliness of the parts and the absolute passability of the oil flows.
General description of the engine
The engine in question is a 4-cylinder, in-line, overhead camshaft (OHC) liquid-cooled diesel engine. 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 powertrain.
The camshaft is installed inside the cylinder head, the drive of which is carried out by a toothed belt transmission from the crankshaft. The intake and exhaust valves are seated in the guide bushings pressed into the head body. Each of the valves is closed by the force developed by a single coil spring. The cams of the camshaft act on the valves directly through hydraulic tappets seated in individual seats. Oil is supplied to the hydraulic compensators and for lubrication of the tappets is carried out through oil ducts cast in the head body.
Skoda Felicia cars 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 a thrust bearing and controls the axial play of the shaft.
The intermediate shaft, driven by the timing belt, ensures the operation of the brake booster vacuum pump and the engine lubrication system oil pump.
The circulation of the coolant is provided by a water pump driven by an auxiliary belt. Details on the operating principle of the cooling system can be found in the materials of Chapter Cooling and heating systems.
The forced lubrication system of the engine is organized by means of a pump driven directly from the intermediate shaft. Oil is taken from the oil pan through an oil intake equipped with a mesh filter. Before being fed into the engine lubrication circuit, the oil is driven through an externally mounted full-flow replaceable oil filter. After passing through the filter, the oil enters the cylinder head, where it is used to lubricate the bearing journals of the camshaft and hydraulic valve tappets, and then, into the engine crankcase, to the main and connecting rod bearings, piston pins and cylinder mirrors. Sprayers are mounted in the base of each of the cylinders, providing oil supply to the under-piston space in order to increase the efficiency of heat removal. An oil cooler included in the cooling system tract lowers the oil temperature before it is fed to the engine.
The engine arrives at the Skoda plant without attachments (in addition to the power supply system equipment) and is already equipped with a generator, water and steering pumps on the conveyor. The auxiliary units are driven by a belt transmission.
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) Removing and installing the accessory drive belt;
- b) Removing and installing the camshaft;
- c) Replacing the camshaft oil seal;
- d) Removing and installing the camshaft gear;
- e) Removing and installing the water pump (see Chapter Cooling and heating systems);
- f) Replacing the crankshaft seals;
- g) Removing and installing the crankshaft gear;
- h) Removing and installing the cylinder head;
- i) Checking the condition and replacing the powertrain suspension supports;
- j) Replacing the intermediate shaft seal;
- k) Removing and installing the oil pump and oil intake assembly;
- l) Removing and installing the oil pan;
- m) Removal, condition check and installation of the timing belt with toothed wheels and front cover.