2. High mileage is not always an indicator of the need for major repairs and, conversely, low mileage is not a guarantee that repairs are not needed. Probably the most important factor is the frequency of engine maintenance. An engine that has had its oil and oil filter changed frequently and regularly, and that has had all other maintenance procedures performed, should have a long and reliable life. Conversely, an engine that has been neglected for regular maintenance may need to be overhauled very quickly.
3. Very high oil consumption is indicative of problems with the piston rings, valve stem seals and/or valve guides. However, before deciding to replace the gauge and caps, check if the excess oil consumption is the result of ordinary leaks. To determine the true cause, perform a compression test as described in Part A of this chapter.
4. Check the oil pressure with a gauge installed in place of the oil pressure switch and compare the obtained pressure value with the specifications. If the pressure is low, it is most likely that the main and connecting rod bearings and / or the oil pump gears are worn out.
5. Reduced power, rough running, knocking or metallic noises in the engine, increased noise in the valve train and high fuel consumption may also indicate in favor of an overhaul, especially if these symptoms appear at the same time. If a full service does not correct the situation, the only solution is to repair the engine.
6. Engine overhaul includes restoring all internal parts to new engine specifications. Cylinder liners are replaced during overhaul (where they are installed), pistons and piston rings. As a rule, new main and connecting rod bearings are installed; if necessary, to restore the size of the necks, you can replace the crankshaft. Valves are also serviced, since at the time of repair they are not in the best condition. If the engine is disassembled, other parts such as distributor, starter and alternator. can also be disassembled and repaired. The end result of the repair should be an engine "like New", which will serve without problems for many kilometers.
Note: During a major overhaul, critical components of the cooling system, such as hoses, thermostat and water pump, must be replaced. It's also a good idea to add an oil pump to this list. The radiator should be carefully inspected to make sure it is not leaking or clogged.
7. Before starting an engine repair, read all of the repair procedure in its entirety to familiarize yourself with the requirements and scope of work. An engine overhaul is not a difficult job if you follow all the instructions exactly, have the necessary tools and fixtures, and meet all technical requirements. However, repair is a very time-consuming operation. Plan for it to take at least two weeks, especially if you need to work on the restoration of parts. Check the availability of engine parts and make sure you have or can borrow all the necessary tools and fixtures. Most of the work can be done using a universal hand tool, however, to check the details, you will need some high-precision measuring instruments. You may often need expert advice on repairing or replacing parts.
Note: In order to make the right decision about the necessary work to restore parts (especially cylinder block/crankcase or crankshaft), completely disassemble the engine and check all parts. The condition of these parts is a determining factor when deciding whether to assemble an engine from "relatives" parts or buying remanufactured units. Therefore, do not purchase or install parts until you have thoroughly inspected them. The basic rule is that time determines the cost of repairs, so do not install worn or non-standard parts.
8. As a final note, remember that long life with minimal care of a remanufactured engine is ensured by careful assembly in a clean environment.