If increased noise or knocks are heard during engine operation, then their probable cause may be wear of the connecting rod or main bearing shells. Unscrew the pressure sensor and measure the oil pressure with a manometer, compare the value obtained with that indicated in the technical data. If the pressure is low, the cause may be wear on the thrust bearings or the oil pump. Loss of power, engine dips, increased noise from the gas distribution mechanism, increased fuel consumption indicate the need for a major overhaul, especially if all of these symptoms appear at the same time. If all adjustments do not lead to improvement, then repair is most appropriate.
An overhaul consists in restoring engine parts to the condition specified in the technical data for a new engine. During the overhaul, piston rings are replaced, and the cylinder walls are bored (or honed) to repair size. After the repair of the cylinders, the installation of new pistons will be required. The connecting rod and main bearings must also be replaced; if necessary, the crankshaft should be ground to restore clearances with the connecting rod and main bearings. As a rule, the valve mechanism is not replaced, since its condition at the time of repair is usually satisfactory. During the overhaul of the engine, the carburetor, ignition distributor, starter and generator are also repaired. As a result, the engine should have the qualities of an almost new unit and serve without fail for a long time. Before starting an engine overhaul, review the repair work description to determine the extent of the work to be done. Major repairs are simple, but time consuming. Approximately it will take at least two weeks, especially if for repair and restoration of parts (grinding, boring) will have to go to a specialized workshop. Check the availability of spare parts and take care of purchasing the necessary special tools and equipment in advance.
Almost all work can be done with a standard set of tools, although precise measuring instruments will be needed to check and determine the suitability of certain parts. Often, the condition of parts is checked in specialized workshops, in which they receive recommendations for replacing or restoring parts.
Since the condition of the cylinder block is a determining factor, a decision on its further repair or on the purchase of a new repair cylinder block should be made only after a thorough check of its technical condition. Make it a rule that the true cost of repair is time, then you won't have to pay for the installation of worn or repaired parts.
In conclusion, we note that the assembly of any units should be carried out very carefully, in a clean room, in order to avoid further failures of the repaired engine.
Attention! You should contact the car service workshops only after completely disassembling the engine and checking all the parts, especially the cylinder block, in order to decide which maintenance and repair operations will be performed in the workshops.