2.2.2. General information about major maintenance of the engine
Question of, whether it is necessary to carry out complete major maintenance of the engine and when it is not always simple to solve as some circumstances are necessary to consider.
Considerable run is not an obligatory sign of need of major maintenance, at that time small run does not cancel such need. The most important reason is periodicity of maintenance. The engine in which oil and the filter was regularly and often replaced, also as other categories of maintenance were carried out, most possibly will reliably serve many thousands kilometers. And, on the contrary, the unattended engine can demand major maintenance early very much.
The raised consumption of oil is a sign of that piston rings, maslosjemny caps and/or directing valves are worn-out. For determination of necessary amount of works make check of extent of compression in cylinders (see. Section Check of extent of compression).
Check pressure of oil: Unscrew the sensor of pressure of oil and on its place attach a measuring instrument of pressure of oil. Measure pressure of oil at normal working temperature of the engine. Compare your indications of pressure of oil with given in the Size table and adjusting data at the end of the Management. If indications are much lower given (and if oil and the oil filter are in a normal state), bearings of a cranked shaft or the oil pump, possibly, are worn-out. On engines M10 and М30 the sensor of pressure of oil is located at the top of the left back wall of a head of cylinders. On M20 engines the sensor will screw in a lateral wall of the block of cylinders, below the oil filter. On M40 engines the sensor will screw in a back wall of the case of the oil filter.
Capacity losses, not smooth rotation, knocks or metal sounds in the engine, also can indicate excessive noise of a drive of valves and high consumption of fuel need of major maintenance, especially if these signs are present at the same time. If complete adjustment does not correct a situation, the unique exit are considerable mechanical works.
Major maintenance of the engine includes restoration of internal elements to a condition of the new engine. At major maintenance new piston rings are established and surfaces of walls of cylinders (are ground and/or хонингуются) are restored. If grinding is carried out in a mechanical workshop, new pistons of the increased size are established. Radical bearings and bearings of rods are usually replaced on new and, if necessary, the cranked shaft for restoration of necks is ground. Usually valves also are served, as by this time they are not in perfect tune. At major maintenance of the engine also components as the ignition distributor, the starter and the generator, also can be restored. As a result the engine should become similar new and provide many thousands kilometers of trouble-free run.
At major maintenance of the engine surely it is necessary to replace critical components of system, also as hoses, driving belts, the thermostat and water the pump It is necessary to check carefully a radiator to be convinced that it is not littered and does not proceed (look Heads Routine maintenance of the car and cooling System). Besides, it is not recommended to make repair of the oil pump - always at restoration of the engine establish the new.
Before the beginning of major maintenance of the engine read descriptions of operations to familiarize with amount of works and requirements to them.
Major maintenance is not difficult if carefully to follow instructions, to have necessary tools and the equipment and to pay close attention to all specifications, however, all this demands time. Plan works from calculation that the car will be under repair, at least, two weeks, especially, if for repair or restoration it is necessary for detail to send in automobile repair shop.
Check availability of spare parts and in advance be convinced that any necessary tools and the equipment can be received. The most part of works can be executed by means of ordinary manual tools though check of a condition of details for the purpose of determination of need of their replacement will need some precision measuring tools. Often in automobile repair shop check of a condition of parts is made and recommendations about their restoration and replacement are made.
Before making the decision, what service and repair should be executed by automobile repair shop, make complete dismantling of the engine and check of a condition of all components, especially, the block of cylinders. As the condition of the block of cylinders is the main factor at making decision on major maintenance of the former engine or on acquisition restored, never get parts and do not make stanochny processing of other components before do not execute careful check of a condition of the block of cylinders. Generally, time makes the main cost of major maintenance therefore it is not necessary to establish worn-out or non-standard parts.
In summary we will notice that for providing the greatest service life and the smallest problems with the restored engine, all works should be made carefully, in faultlessly pure situation.