The material offered to the attention of readers contains a wide range of information - from practical advice on purchasing the necessary spare parts to a detailed step-by-step description of the procedure, removal, condition check, restoration repair and installation of internal engine components.
The procedure descriptions are based on the assumption that the engine is completely removed from the vehicle and installed on a mounting stand or sturdy workbench. For all information about engine repair procedures that can be performed without removing the latter from the vehicle (in situ), see Parts Engine Repair Without Removing It From The Car - Civic Models and Engine Repair Without Removing It From the Vehicle - Integra Models of this Chapter.
It is not always easy to determine the moment when a major overhaul of the power unit is necessary. A whole host of different factors must be taken into account.
High engine mileage is not necessarily a sign that the engine needs a major overhaul. On the other hand, low mileage is also not a sufficient guarantee of the serviceability of the power unit. Perhaps the main factor determining the service life of the engine is the frequency and regularity of general and routine maintenance procedures. With normal care, the engine will reliably serve for many, many thousands of kilometers, while a careless attitude to the implementation of routine maintenance procedures coupled with a careless driving style can lead to the need for a major overhaul of the power unit after a very short period of time.
Excessive engine oil consumption can be considered a signal that it is necessary to check the condition of the piston rings, valve stem seals and/or valve guides. Naturally, first of all, you should make sure that the oil loss is not associated with the development of its external leaks. Contact a qualified specialist for help to determine the general condition of your car's engine based on the results of the compression pressure test in the cylinders (see General information about settings and adjustments) and measurements of the vacuum depth at different initial parameters (see Checking fluid levels (every 400 km or weekly)).
Loss of developed power, disruption of rotation stability, excessive noise background of the valve mechanism, increased fuel consumption are usually quite characteristic signs of the need for a major overhaul of the engine, especially when all these factors appear simultaneously. If performing a full range of adjustments does not help in eliminating the problems, the only way out of the situation will be to carry out general mechanical work to restore the engine.
Major repairs of the power unit involve restoring all its operating parameters to the level typical of a new engine. During a major repair, piston rings are replaced and cylinder mirrors are restored (turning and/or honing). In case of cylinder boring, pistons of the corresponding repair size are selected. Main and connecting rod bearings are usually replaced, if necessary, crankshaft journals can be bored and restored. Valve maintenance is mandatory, the condition of which at the time of the need for a major overhaul of the engine almost certainly leaves much to be desired. In parallel with the general overhaul of the power unit, a refurbishment of such auxiliary components as the ignition distributor, starter and generator is usually also carried out. As a result of the repair, the engine returns to the parameters typical of a new unit, and it will be able to reliably serve for many, many thousands of kilometers.
Note: Critical cooling system components such as hoses, drive belts, thermostat and water pump MUST be replaced with new ones when performing a major engine overhaul. In addition, the condition of the radiator should be carefully checked (see Chapter Cooling and heating systems). If signs of developing leaks or obstruction are detected, the radiator should also be replaced.
Many branded auto service workshops do not provide a guarantee for the operation of a rebuilt engine without professional cleaning and repair of the radiator. Do not forget to check the condition of the oil pump (see the relevant Sections of Parts Engine Repair Without Removing It From The Car - Civic Models and Engine Repair Without Removing It From the Vehicle - Integra Models of this Chapter).
Before proceeding with major engine repairs, carefully read the materials in this Part of the Chapter Engine, theoretically preparing yourself for the upcoming work. Note that major engine repairs do not require high professional training from the performer, but they do take a lot of time. You should plan to stop using the car for at least two weeks, especially if you need to seek help from a mechanical workshop to perform individual repairs. Do a little marketing by checking the availability of spare parts, tools and equipment. Prepare all the necessary materials in advance. Most of the work can be done using a regular set of metalworking tools, but some of the tests to determine the suitability of certain components for further use require the use of precision equipment. In doubtful situations, seek help from specialists at the auto service workshop, who will always help you decide on the need to replace or repair any internal engine component.
Note: Before taking any parts to a car service center for refurbishment, perform a complete disassembly of the engine and all its internal components. Remember that the deciding factor in the advisability of an engine overhaul is the condition of its cylinder block. It is often cheaper and more reliable to replace a worn-out engine with a reconditioned one. Never start purchasing replacement components until you have thoroughly examined the condition of the block. Remember that time is the main cost factor in performing an engine overhaul, and therefore, there is no point in wasting it on installing worn-out or non-standard units and components.
In conclusion, we note that all efforts to perform restoration repairs of worn components will be wasted if there is a careless attitude to the requirement of careful observance of cleanliness during assembly of the unit.