| Cause of malfunction | Method of elimination |
| The engine will not start | |
| No fuel pressure in the rail: fuel lines are clogged the fuel pump is faulty the fuel filter is clogged the fuel pressure regulator is faulty The ignition system is faulty | Flush and blow out the fuel tank and fuel lines Replace the fuel pump Replace the fuel filter Replace the fuel pressure regulator Cm. "ECM (Electronic Engine Management System(fuel injection system))" |
| Engine runs rough or stalls at idle | |
| Insufficient pressure in the fuel rail The idle speed control valve is faulty Air leakage through the engine crankcase ventilation hoses and the hose connecting the intake pipe to the brake booster Clearances in the valve drive mechanism are damaged The ignition system is faulty | See above "Engine won't start" Replace the idle air control valve Tighten the mounting clamps, replace damaged hoses Perform valve clearance adjustment (see "Adjusting valve clearances") Cm. "ECM (Electronic Engine Management System(fuel injection system))" |
| The engine does not develop full power and is not responsive enough | |
| Incomplete throttle opening Throttle position sensor is faulty Insufficient pressure in the fuel rail The air filter is dirty The ignition system is faulty Clearances in the valve drive mechanism are damaged Insufficient compression - below 1.0 MPa (10 kgf/cm.sq.): the cylinder head gasket is blown burnt pistons, broken or stuck piston rings poor valve seat fit excessive wear of cylinders and piston rings | Adjust the throttle actuator (see "Adjusting and replacing the throttle cable") Replace the throttle position sensor See above "Engine won't start" Replace the air filter Cm. "ECM (Electronic Engine Management System(fuel injection system))" Perform valve clearance adjustment (see "Adjusting valve clearances") Replace the cylinder head gasket Clean the rings and piston grooves from carbon deposits, replace damaged rings and pistons Replace damaged valves, polish valve seats Replace pistons, bore and hone cylinders |
| Insufficient oil pressure in a warm engine | |
| Using the wrong grade of oil Dilution or foaming of oil due to penetration of fuel or coolant into the oil pan Contamination of the working cavity or wear of the oil pump parts Clogged oil filter Loose or clogged oil receiver Excessive reduction in clearance between the oil receiver and the bottom of the oil pan or damage to the oil receiver caused by impact with a road obstacle Increased clearance between main and connecting rod bearing shells and crankshaft journals Cracks, pores in the walls of the cylinder block oil channels or clogged oil lines Loose or missing oil channel plugs | Replace the oil with the recommended one Eliminate causes of fuel or coolant leakage. Change the engine oil Flush or repair the oil pump Replace the oil filter Secure the oil receiver, wash its filter Straighten the deformed oil pan, replace the damaged oil receiver if necessary Grind the crankshaft journals and replace the bearings Repair the cylinder block. If the defect cannot be eliminated, replace the cylinder block Restore the tightness of the plugs, install missing plugs |
| Knocking of crankshaft main bearings | |
| Typically, the knocking sound of the crankshaft main bearings is dull and metallic. Detected when the throttle valve is opened sharply at idle speed. Its frequency increases with increasing crankshaft rotation speed. Excessive axial clearance of the crankshaft causes a knock that is sharper, with uneven intervals, especially noticeable with a smooth increase and decrease in crankshaft speed | |
| Insufficient oil pressure The flywheel mounting bolts are loose Increased clearance between journals and main bearing shells Increased clearance between thrust half rings and crankshaft | See above "Insufficient oil pressure in a warm engine" Tighten the flywheel mounting bolts to the recommended torque Grind the main bearing journals and replace the liners Replace the thrust half rings with new ones or thicker ones, check the clearance |
| Knocking of connecting rod bearings | |
| Usually the knock of connecting rod bearings is sharper than the knock of main bearings. It can be heard when the engine is idling and when the throttle valve is opened sharply. The location of the knock can be easily determined by disconnecting the spark plugs one by one | |
| Insufficient oil pressure Excessive clearance between the crankshaft journals and the bearings | See above "Insufficient oil pressure in a warm engine" Replace the bearings and grind the crankshaft journals |
| Knocking of pistons | |
| The knock of the pistons is usually muffled and dull; caused by the piston "beating" in the cylinder. It is best heard at low crankshaft speed and under load | |
| Increased clearance between pistons and cylinders Excessive clearance between piston rings and piston grooves The piston is not installed correctly (the piston pin hole is offset towards the left side of the engine) | Replace pistons, bore and hone cylinders Replace rings or pistons with rings Install the piston correctly |
| Increased noise from the valve timing mechanism | |
| Low oil pressure in the lubrication system Valve spring failure Excessive clearance between the valve stem and the guide bushing caused by wear Camshaft cam wear | See above "Insufficient oil pressure in a warm engine" Replace the valve spring Replace the guide bushing with a repair one, having reamed the hole in it accordingly Replace the camshaft |
| A knock on a cold engine, audible for two to three minutes after starting and increasing in intensity as the crankshaft speed increases | |
| Increased clearance between pistons and cylinders Loose crankshaft pulley fastening | A piston knock that disappears after the engine warms up is not a sign of a malfunction. If knocking is constant, replace pistons, bore and hone cylinders Tighten the crankshaft pulley mount |
| Brief knocking sounds immediately after starting the engine | |
| Using the wrong grade of oil (low viscosity) Increased crankshaft axial clearance Increased clearance in the front main bearing | Replace the oil with the recommended one Replace the crankshaft thrust washers Replace the front main bearing shells |
| Knocking in a warm engine at idle speed | |
| Loose or worn alternator drive belt Noise from the valve timing mechanism parts Using the wrong grade of engine oil Increased clearances between piston pins and piston boss holes Increased clearances between the crankshaft journals and the bearings The axes of the upper and lower connecting rod heads are not parallel The piston is not installed correctly (the piston pin hole is offset towards the left side of the engine) | Adjust the alternator belt tension or replace it See above "Increased noise from the valve timing mechanism" Replace engine oil with recommended one Replace pistons and piston pins Replace the bearings and grind the crankshaft journals Replace the connecting rod Install the piston correctly |
| Loud knocking in a warm engine when the crankshaft speed increases | |
| Torsional vibration damper failure in the crankshaft pulley hub Excessive tension of the alternator drive belt or the appearance of cracks and breaks on it The flywheel mount is loose Excessive increase in clearances between the connecting rod and main bearing shells of the crankshaft | Replace the crankshaft pulley Adjust the alternator belt tension, replace the damaged alternator belt Tighten the flywheel mounting bolts to the specified torque Regrind the crankshaft journals to the repair size and replace the bearings |
| Increased engine vibration | |
| Crankshaft imbalance Pistons of different weights are installed Valve drive clearances are damaged Uneven compression values in cylinders The powertrain suspension mounts are severely worn or hardened The crankshaft pulley mount is loose | Remove and balance the crankshaft Disassemble the connecting rod and piston group, select pistons by weight Adjust the valve clearances (see "Adjusting valve clearances") Cm. "Checking the compression in the cylinders" Replace engine mounts Tighten the crankshaft pulley mount |
| Engine detonation knocks when operating under load | |
| Using low octane gasoline The knock sensor is faulty The ECU is faulty (electronic control unit) engine | Fill with gasoline of the appropriate octane rating Replace the knock sensor Replace the ECU (electronic control unit) engine |
| Increased oil consumption | |
| Oil leaking through engine seals The crankcase ventilation system is clogged Wear of piston rings or engine cylinders Broken piston rings Coking of oil scraper rings or grooves in piston grooves due to the use of non-recommended oil Worn or damaged valve stem seals Increased wear of valve stems or guide bushings | Tighten the fasteners or replace the gaskets and seals Flush the crankcase ventilation system components Rebore the cylinders and replace the pistons and rings Replace piston rings Clean the rings and grooves from carbon deposits, replace the engine oil with the recommended one appendix 3 Replace the valve stem seals Replace valves or guide bushings |
| Engine overheating | |
| Insufficient amount of fluid in the engine cooling system The outer surface of the radiator is heavily contaminated Thermostat is faulty The electric fan of the engine cooling system is faulty The expansion tank cap valve is faulty (is constantly open, which is why the system is under atmospheric pressure) Using low octane gasoline | Add coolant to the engine cooling system Clean the outer surface of the radiator with a jet of water Replace Thermostat Check the fan motor and its relay, replace faulty units Replace the expansion tank cap Fill with gasoline of the appropriate octane rating |
| Rapid drop in fluid level in expansion tank | |
| The radiator is damaged Damage to hoses or gaskets in pipeline connections, loose clamps Fluid leaking through the water pump seal The cylinder head gasket is damaged Fluid leakage through microcracks in the block or cylinder head | Repair the radiator or replace it Replace damaged hoses or gaskets, tighten hose clamps Replace the water pump Replace the cylinder head gasket Check the tightness of the block and cylinder head; if cracks are found, replace damaged parts |
[Original text can be found on the website: ladaman.ru]