2.2.2. General information about capital repairs of the engine
Question of whether it is necessary to make complete capital repairs of the engine and when not always just to solve as it is necessary to consider several circumstances.
The considerable run is not an obligatory sign of need of capital repairs, at that time the small run does not cancel such need. The most important reason is frequency of maintenance. The engine in which oil and the filter was regularly and often replaced also as other categories of maintenance were carried out, will most possibly reliably serve many thousands of kilometers. And, on the contrary, the unattended engine can demand capital repairs very much early.
The raised consumption of oil is a sign that piston rings, oil scraper caps and/or guides of valves are worn-out. Make check of extent of compression in cylinders for determination of necessary amount of works (see the Section Check of Extent of Compression).
Check oil pressure: Unscrew the sensor of pressure of oil and on its place attach the oil pressure measuring instrument. Measure oil pressure at a normal working temperature of the engine. Compare your indications of oil pressure with provided in the Size table and adjusting data at the end of the Management. If indications considerably below given (and if oil and an oil filter are in the normal state), then bearings of a bent shaft or the oil pump are probably worn-out. On M10 and M30 engines 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 is screwed in a sidewall of the block of cylinders, below an oil filter. On M40 engines the sensor is screwed in a back wall of the case of an oil filter.
Losses of power, not smooth rotation, knocks or metal sounds in the engine, excessive noise of the drive of valves and high consumption of fuel can also indicate the need of capital repairs, especially if these signs are present at the same time. If full adjustment does not correct a situation, then the only exit are considerable mechanical works.
Capital repairs of the engine include restoration of internal elements to a condition of the new engine. At capital repairs new piston rings are established and surfaces of walls of cylinders are restored (are ground and/or honingutsya). If grinding is carried out in a mechanical workshop, then new pistons of the increased size are installed. Radical bearings and bearings of rods are usually replaced on new and, if necessary, the bent shaft for restoration of necks is ground. Usually valves are also served as by this time they are not in perfect tune. At capital repairs of the engine also components as the ignition distributor, a starter and the generator, can be also restored. As a result the engine has to become similar new and provide many thousands of kilometers of a trouble-free run.
At capital repairs 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 (watch Chapters Routine maintenance of the car and the Cooling system). Besides, it is not recommended to make repair of the oil pump - always at restoration of the engine establish new.
Before capital repairs of the engine read descriptions of operations to get acquainted with the amount of works and requirements to them.
Capital repairs are not difficult if carefully to follow instructions, to have necessary tools and the equipment and all this demands to draw close attention to all specifications, however, time. Plan works from calculation that the car will be under repair, at least, two weeks, especially, if the detail for repair or restoration needs to be sent to 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 performed by means of usual hand tools though check of a condition of details for the purpose of definition of need of their replacement will require some precision measuring tools. Often in automobile repair shop check of a condition of parts is made and recommendations of their restoration and replacement are made.
Before making the decision what service and repair have to be executed by automobile repair shop, you make full dismantling of the engine and check of a condition of all components, especially, of the block of cylinders. As the condition of the block of cylinders is the main factor at making decision on capital repairs of the former engine or on acquisition restored, never get parts and you do not make machine 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 capital repairs therefore it is not necessary to establish worn-out or non-standard parts.
In conclusion we will notice that for providing the greatest service life and the smallest problems with the restored engine, all works have to be performed carefully, in faultlessly pure situation.