Check and replacement of inserts
Even during the correct work of lubricant system and a permanent care of it, influence of friction on inserts and a cranked shaft is inevitable over time. It is shown that on necks of the crankshaft the roughness, grooves is gradually formed. Oil under pressure freely passes through such "tunnels", and the oil film is formed not as has to. As a result of friction force increase, and the crankshaft is exposed to wear more and more.
Therefore through a certain number of kilometers of run (a miscellaneous each make of the car), is required to carry out repair of the engine, replacing inserts of a cranked shaft with obligatory polishing of necks of the crankshaft (eliminating a roughness).
For various brands of cars a number of the repair sizes can be various. So, if for models their VAZ 4, then for GAS – 6, with the same step. Some producers on inserts of the crankshaft put their size. If, for example, on an insert it is written "0,25", it means that such insert has the 1st repair size.
The size of inserts which will need to be established upon termination of repair also depends on degree of a roughness which will be eliminated with boring and polishing. Can quite be that at strong wear the 1st repair size will need to be passed, at once having passed to the second.
One of ways of check of degree of wear of inserts (except direct measurement of their thickness) is use of a set of special control probes of paper or a copper foil. Probes have thickness with a step to 0,025 mm. Installing the probe between an insert and a neck of a shaft, tighten as it is necessary, all connections, and then try to turn the crankshaft. This operation is carried out until the crankshaft is not scrolled with notable effort. Value of thickness of the used probe will also correspond to gap size.
Copper probes are oiled, at the same time, and the shaft is turned no more, than by 90 degrees, in order to avoid damage of a surface of an insert.
It is the best of all to trust work on check, selection and replacement of inserts of the crankshaft to the experts who are a good judge of similar business and having considerable experience. In each case specific features and subtleties which not knowing person can not notice are possible. Namely they will affect then negatively all result of work. Be wise – entrust difficult work to professionals!