4.1. General information and preparatory operations
The description of the most typical and important procedures of service and repair of engines is provided in this chapter, behind an exception, demanding special skills and tools, such as – these works it is necessary to charge procedures of major maintenance of the engine to specialists of car-care center. Petrol M60/1, M60/2 and M73 engines, and also diesel M57 and M67 engines below are considered. Works on M51, M52 and M62 engines are made similarly; information on repair of these engines is presented in the Guide of No. of 149 ARUS series to car repairs of BMW of the 5th series from 1996 to 2001 вып.
On considered cars engines of six types are established: 6-cylinder turbodiesel of M51 (SOHC), 6-cylinder diesel engine of M57 (DOHC), 6-cylinder petrol M52 (DOHC) engine, 8-cylinder V-shaped petrol (M60, M62) and diesel (M67) engines (DOHC), and also 12-cylinder V-shaped petrol M73 (SOHC) engine. Abbreviations of SOHC and DOHC indicate existence respectively one or two camshafts on a number of cylinders (and, therefore, 2-x or 4-x valves on the cylinder), located in the top part of the engine. The power unit is established along the car and acts in film from an impellent compartment up by means of the crane.
Its head and the block of cylinders of the M52 engine are cast from an aluminum alloy. Unlike traditionally applied cast iron the aluminum alloy has higher heat conductivity and smaller weight. It promotes the best cooling and lower fuel consumption.
The block of cylinders of the turbodiesel M51 engine is cast from cast iron, a head of cylinders – from an easy alloy. At the increased wear and existence задиров on walls of walls of their cylinders it is possible хонинговать with the subsequent replacement of old pistons by pistons of the repair sizes.
The head of cylinders at all engines has a so-called cross-section purge. It means that the fuel mix arrives in cylinders on the one hand, and the fulfilled gases (OG) leave with another. Such scheme promotes faster gas exchange.
The drive of GRM is carried out from a cranked shaft through a chain; for a drive of auxiliary units multiridge belts are used. M52 engines are equipped with system of adjustment of phases GRM (VANOS) by means of shift of an inlet camshaft concerning its asterisk. Adjustment of phases GRM the control unit the engine (ECM, DME) depending on number of turns of a cranked shaft by means of opening and closing of the special oil valve operates.
Valves are actuated from camshafts through hydraulic pushers. Need of adjustment of klapanny gaps in the course of maintenance is absent. On SOHC engines inlet and final valves are given from one shaft, and on DOHC engines the separate camshaft is intended for a drive of inlet and final valves.
But the piston are 2 kompressionny and one maslosjemny ring. The cranked shaft is located in radical bearings.
Supply of oil in system of greasing is carried out by the oil pump which at the 6-cylinder petrol engine settles down in front in the pallet of a case and brought from a cranked shaft. At the diesel M51 engine the oil pump is in a cover of a chain of a drive of GRM and is brought through a tooth gearing. Oil is sucked in from the pallet of a case and through openings and pipelines moves to bearings of cranked and distributive shaft, and also to working surfaces of cylinders.
The pump of cooling liquid is located in a forward part of the block of cylinders. From a pump shaft via the vyazkostny coupling at achievement of the corresponding temperature the cooling fan is given. The drive of the water pump is carried out through a multiridge belt which at the same time gives the generator. The system of cooling is filled with an antifreeze mix, means of protection from corrosion and water with the low content of lime.
Preparation of an air and fuel mix is supervised by system of injection which together with system of ignition and some other systems is a part of a control system of the engine. Thanks to it the stable low content of harmful substances in the fulfilled gases is provided. The system of ignition has no mobile elements that excludes their wear. At the diesel engine fuel distribution on cylinders is regulated by the electronic control unit (ECM, DDE).
Petrol engines are calculated for work on AI-95 gasoline, however thanks to existence of detonation regulation can be applied and other grades of fuel. If AI-98 gasoline is used, under normal conditions operation fuel consumption decreases and engine capacity raises. When using AI-91 gasoline engine capacity decreases and fuel consumption raises.
Before carrying out any procedures of service of the engine make cleaning of an impellent compartment and external surfaces of the power unit with application of special solvent. Such processing will allow to avoid dirt hit in the engine.
In case of need, the forthcoming work defined by character, it is possible to remove a cowl for the purpose of ensuring freedom of access to components subject to service (see. Head Body). In order to avoid casual damage of a paint and varnish covering cover car wings with special covers or old blankets.
It is possible to consider an excessive consumption of impellent oil as a signal about need of carrying out check of a condition of piston rings, maslootrazhatelny caps and/or directing plugs of valves. Naturally, first of all, it is necessary to make sure that losses of oil are not connected with development of its external leaks. Check a compression in cylinders (see. The section Check of kompressionny pressure) to define the general condition of the engine.
Loss of the developed capacity, violation of stability of turns, excessive noise of the klapanny mechanism and the increased fuel consumption usually are rather characteristic signs of need of performance of major maintenance of the engine, in particular, when all these factors are shown at the same time. If performance of a full range of settings does not help with elimination of the problems, carrying out the general mechanical works on engine restoration will be the unique way out.
Major maintenance of the power unit means recovery of all of its working parameters to level, characteristic for the new engine. During major maintenance replacement of piston rings and restoration of mirrors of cylinders (a pro-point and/or a honingovaniye) is without fail made. Replacement of radical and shatunny bearings of a cranked shaft is usually carried out, the pro-point and restoration of his necks can be in case of need made. Service of the valves which condition at the moment of emergence of need for performance of major maintenance of the engine almost for certain leaves much to be desired is without fail carried out. In parallel with carrying out the general repair of the power unit also regenerative repair of a starter and the generator is usually made.
Major maintenance of the engine does not demand from the performer of high vocational training, however takes away a lot of time. It is necessary to plan refusal of using the car for the term of not less than two weeks, in particular in need of the request for the help in a mechanical workshop for the purpose of performance of separate recovery operations.
The most part of works can be executed with application of a usual set of the metalwork tool, however some of checks by determination of suitability of separate components to further use demand use of the precision measuring equipment. In doubtful situations address for the help to experts HUNDRED.
Do not forget that a determinant in a question of expediency of performance of major maintenance of the engine is the condition of the block of its cylinders. Frequent cheaper and more reliably it appears to replace the worn-out engine restored.
In summary it is possible to notice that all efforts on performance of regenerative repair of worn-out components will appear spent for nothing at the negligent relation to the requirement of observance of purity at unit assembly.