Engine overhaul is a necessity (Chevrolet Lumina 1)

Determining if and when an engine overhaul is needed is not always easy, as there are a number of factors to consider when making this decision.

High mileage of a car does not necessarily mean the need for major repairs, just as low mileage does not exclude it. Perhaps the deciding factor here is the frequency of maintenance. An engine that has had its oil and filters changed frequently and has had the required adjustments performed will not give you any problems at high mileage. On the contrary, a running engine may very quickly require major repairs.

Excessive oil consumption indicates the need to pay attention to the piston rings, valve seats and/or valve guides. But before you suspect the rings and/or guide bushings, check for oil leaks. To determine the amount of repair work required, perform a compression pressure test (compressions) in cylinders (see section 3).

Remove the oil pressure sensor and measure the pressure using a test pressure gauge installed in its place (see illustrations). Compare the results with the specifications given in this chapter. A general rule of thumb is to increase engine oil pressure by 10 psi for every 1000 rpm increase in engine speed. Oil pressure that is too low may be due to worn bearings and/or oil pump.









Loss of power, rough running, knocking and metallic noises in the engine, valve knocking and high fuel consumption may also indicate the need for a major overhaul, especially if they occur simultaneously. If all possible adjustments do not correct the situation, the only way out is to carry out repair work.

An engine overhaul involves restoring the internal parts to a condition that matches the specifications of a new engine. During a major overhaul, piston rings are replaced and cylinder walls are treated (reboring and honing). If reboring is performed in a workshop, new pistons of larger (repair) dimensions are installed. Main bearings, connecting rod bearings and camshaft bearings are usually replaced and, if necessary, the crankshaft may be reground to restore the condition of the journals. As a rule, the valves are also serviced, since their condition at the time of repair is usually far from ideal.

Note: Cooling system components such as hoses, drive belts, thermostat and coolant pump must be replaced with new ones during engine overhaul. The radiator should be carefully inspected for possible leaks and blockages (see chapter 3, section 5). It is not recommended to repair the oil pump on an engine with a working volume of 3.1 liters - when repairing the engine, always install a new pump.

Before you begin a major engine overhaul, review all planned operations to become familiar with the scope of work and existing requirements. Engine repairs are not too difficult if you follow the instructions carefully, have all the tools and equipment, and pay close attention to the specifications. Check the availability of required spare parts and prepare the necessary tools and equipment in advance. Most of the work can be done with standard hand tools, although some precision measuring equipment will be required to check the condition of parts to determine if they need to be replaced.

Note: Do not rush to make decisions about what service and repair operations will be performed at an auto repair shop until you have completely disassembled the engine and inspected all its parts, especially the cylinder block. Since the condition of the engine block is a deciding factor in deciding whether to rebuild or remanufacture an engine, do not purchase replacement parts or repair other components until the block has been thoroughly inspected. Don't try to save money by installing worn out or non-standard parts.

Finally, to ensure maximum service life of the remanufactured engine with minimum problems, all assembly work must be carried out carefully and in impeccably clean conditions.