2. High mileage does not necessarily mean that an overhaul is necessary, and conversely, low mileage does not eliminate the need for one. Regularity of maintenance is the most important factor to consider. An engine that has had its oil and filter changed regularly, and other required maintenance performed, will provide many thousands of kilometers of trouble-free service. Conversely, a poorly maintained engine may require an overhaul at very low mileage.
3. Excessive oil consumption indicates that the piston rings, valve stem seals and/or their guide bushings are damaged (however, the possibility of leaks should first be ruled out). Perform a compression test and leak test as described in Section 1A, to determine the cause of excessive lubricant consumption.
4. Insert a measuring device into the oil pressure sensor hole, check the pressure and compare the result with the data given in the Specifications. If the pressure is low, the main and connecting rod bearings and/or the oil pump are probably worn.
5. Loss of power, rough running, engine or valve train noise and high fuel consumption may also indicate that the engine needs to be overhauled, especially if all of these factors are present at the same time. If a full service does not resolve the problem, regrinding/replacing worn components is the only solution.
6. A complete engine overhaul involves restoring all internal parts, as well as replacing pistons and piston rings. As a rule, new main and connecting rod bearing shells are installed; if necessary, the crankshaft can be replaced; in addition, the valves are serviced. It is also necessary to carefully inspect the oil pump and replace it if there is any doubt about its condition. When overhauling the engine, it is possible to overhaul the starter and generator as well.
Note: When rebuilding the engine, the coolant hoses, thermostat and water pump should be replaced. Carefully inspect the radiator to ensure that it is not clogged or leaking.
7. Before you begin overhauling the engine, read the description of all procedures and prepare everything you need. If you carefully follow all the instructions and prepare the necessary tools and equipment, the work will not cause any particular difficulties, although it may take a lot of time. Check the availability of the necessary spare parts. The main work can be done with ordinary tools, but precise measuring tools are needed to inspect the parts and determine whether they need to be replaced.
Note: Before deciding what repairs need to be performed, it is necessary to completely disassemble the engine and inspect all components (especially the cylinder block and crankshaft). The condition of these components is the main factor that determines whether the engine can be rebuilt or replaced with a remanufactured unit. Do not purchase parts or repair any components until you have made this decision.
8. To ensure maximum service life of the rebuilt engine, ensure impeccable cleanliness when assembling it.
(Read the original source on the website Audimanual.ru)