2. We inspect the engine from above and on the inspection ditch or overpass from below. Oil leaks may indicate worn oil seals or seals.
3. We start the engine, while the emergency oil pressure warning lamp should go out. If the control lamp lights up at idle after the engine warms up and goes out after increasing the crankshaft speed, then the following may be worn: oil pump gears, crankshaft journals, main and connecting rod bearing shells. If the lamp is constantly on, then the lubrication system or the emergency oil pressure sensor may be faulty. We check the oil pressure in the engine lubrication system using a pressure gauge (see «Oil pressure»).
Warning! Operating the vehicle with insufficient oil pressure in the lubrication system will result in severe engine damage.
4. After warming up the engine, we listen to its work.
Attention! To avoid personal injury, do not touch the moving parts of the engine when performing the following operation (pulleys, belt) and do not touch hot parts of the engine.
5. If an extraneous sound appears with a stethoscope, we determine the area where this sound is most audible.
By the nature of the sound and the place of sound emission, we determine the possible source of the sound and the possible malfunction.
Comment. A clattering ringing sound under the cylinder head cover, as a rule, indicates a malfunction of the hydraulic lifters in the valve drive (see «Hydropushers - removal and installation»), uniform noise in the timing belt area may indicate wear on the idler and idler roller bearings or the coolant pump bearing. Knocks at the bottom of the cylinder block and from the sump side, which increase with increasing engine speed, are caused by a malfunction of the main bearings. In this case, as a rule, the oil pressure in the lubrication system is low. At idle, this sound is low-pitched, and as the speed increases, its tone rises. When you sharply press the gas pedal, the engine emits something similar to a growl - such as «gyr-r-r». Ringing knocks in the middle of the cylinder block are caused by a malfunction of the connecting rod bearings. Rhythmic metallic knocking in the upper part of the cylinder block, audible at all engine operating modes and intensifying under load, is caused by a malfunction of the piston pins. A muffled knock at the top of the cylinder block on a cold engine that subsides and disappears when warmed up can be caused by worn pistons and cylinders. Operating the vehicle with defective bearings and pins will result in engine failure.
6. If oil consumption has increased, and no leaks are found:
- A) warm up the engine to operating temperature.
- b) Disconnect the crankcase ventilation hose from the throttle body.
- V) bring a sheet of paper to the hose. If oil stains appear on the paper, then the cylinder-piston group is worn out. The degree of wear is determined by compression in the cylinders (see «Compression in the engine cylinders»).
- G) if oil mist does not come from the ventilation system, then the cause of increased oil consumption may be wear on the valve stem seals (see «Oil seals - replacement»). In this case, the car will have a smoky exhaust.
Warning! The operation of the engine with a worn-out cylinder-piston group, faulty valve stem seals or low-quality fuel leads to failure of the catalytic converter and oxygen concentration sensor.
Recommendation. During the operation of the car, the engine compartment is intensively polluted, but unlike the body and interior of the car, it is usually deprived of attention when visiting car washes. Therefore, periodically it is necessary to clean the engine and engine compartment (see below).