Cause of malfunction | Remedy |
The engine will not start | |
No fuel pressure in the rail: clogged fuel lines fuel pump faulty clogged fuel filter faulty fuel pressure regulator Faulty ignition system | Flush and blow out the fuel tank and fuel lines Replace fuel pump Replace fuel filter Replace fuel pressure regulator Cm. «ECM (electronic engine management system (fuel injection system))» |
Engine runs erratically or stalls at idle | |
Insufficient pressure in the fuel rail Faulty idle speed controller Air leakage through the crankcase ventilation hoses and the hose connecting the intake pipe to the vacuum brake booster Violated gaps in the valve drive mechanism Faulty ignition system | See above «The engine will not start» Replace idle speed control Tighten the fastening clamps, replace damaged hoses Perform valve clearance adjustment (see «Valve clearance adjustment») Cm. «ECM (electronic engine management system (fuel injection system))» |
The engine does not develop full power and is not throttled enough | |
Incomplete throttle opening Faulty throttle position sensor Insufficient pressure in the fuel rail Air filter dirty Faulty ignition system Violated gaps in the valve drive mechanism Insufficient compression - below 1.0 MPa (10 kgf/cm2): blown cylinder head gasket burnt pistons, breakage or occurrence of piston rings poor fit of valves to the seats excessive wear of cylinders and piston rings | Adjust throttle actuator (see «Throttle cable adjustment and replacement») Replace Throttle Position Sensor See above «The engine will not start» Replace air filter Cm. «ECM (electronic engine management system (fuel injection system))» Perform valve clearance adjustment (see «Valve clearance adjustment») Replace cylinder head gasket Clean the rings and grooves of the pistons from carbon deposits, replace the damaged rings and piston Replace damaged valves, grind valve seats Replace pistons, bore and honing cylinders |
Insufficient oil pressure in a warm engine | |
Using the wrong brand of oil Thinning or foaming of oil due to fuel or coolant entering the oil sump Contamination of the working cavity or wear of the oil pump parts Clogged oil filter Loose or clogged oil pickup Excessive reduction of the gap between the oil receiver and the bottom of the oil pan or damage to the oil receiver caused by hitting a road obstacle Increased clearance between main and connecting rod bearing shells and crankshaft journals Cracks, pores in the walls of the oil channels of the cylinder block or clogging of the oil lines Loose installation of oil channel plugs or their absence | Change oil to recommended Eliminate the cause of fuel or coolant intrusion. Change engine oil Flush or repair the oil pump Change oil filter Fix the oil receiver, wash its filter Straighten the deformed oil sump, if necessary, replace the damaged oil receiver Grind the crankshaft journals and replace the liners Repair the cylinder block. If it is impossible to eliminate the defect, replace the cylinder block Restore the tightness of the plugs, install the missing plugs |
Knocking crankshaft bearings | |
Usually the knock of the main bearings of the crankshaft is dull, metallic. Detected when the throttle is suddenly opened at idle. Its frequency increases with an increase in the frequency of rotation of the crankshaft. Excessive axial clearance of the crankshaft causes a sharper knock, with uneven intervals, especially noticeable with a smooth increase and decrease in the crankshaft speed | |
Insufficient oil pressure Loose flywheel bolts Increased clearance between journals and main bearing shells Increased clearance between thrust washers and crankshaft | See above «Insufficient oil pressure in a warm engine» Tighten the flywheel mounting bolts to the recommended torque Grind the necks of the main bearings and replace the liners Replace thrust washers with new or increased thickness, check clearance |
Knocking rod bearings | |
Usually the knock of the connecting rod bearings is sharper than the knock of the main bearings. It is heard at idle speed of the engine with a sharp opening of the throttle. The place of knocking is easy to determine by turning off the spark plugs one by one | |
Insufficient oil pressure Excessive clearance between crankshaft journals and bearings | See above «Insufficient oil pressure in a warm engine» Replace bearings and grind crankshaft journals |
The knock of pistons | |
The knock of the pistons is usually unvoiced, muffled; called «beating» piston in the cylinder. It is best heard at low engine speeds and under load | |
Increased clearance between pistons and cylinders Excessive clearance between piston rings and piston grooves Piston installed incorrectly (Piston pin bore offset towards left side of engine) | Replace pistons, bore and honing cylinders Replace rings or pistons with rings Install the correct piston |
Increased noise of the gas distribution mechanism | |
Reduced oil pressure in the lubrication system Valve spring failure Excessive clearance between valve stem and guide bushing due to wear Camshaft lobes wear | See above «Insufficient oil pressure in a warm engine» Replace valve spring Replace the guide bushing with a repair one by reaming the hole in it accordingly Replace camshaft |
Knocking on a cold engine, audible for two to three minutes after starting and increasing with increasing engine speed | |
Increased clearance between pistons and cylinders Loose crankshaft pulley | Piston knocking that disappears after the engine warms up is not a sign of a malfunction. With constant knocking, replace the pistons, bore and honing the cylinders Tighten the crankshaft pulley |
Intermittent knocking immediately after starting the engine | |
Using the wrong brand of oil (reduced viscosity) Increased axial clearance of the crankshaft Increased clearance in the front main bearing | Change the oil to the recommended one Replace crankshaft thrust washers Replace front main bearing shells |
Knocking in a warm engine at idle | |
Loose or worn alternator drive belt Noise of parts of the gas distribution mechanism Using the wrong brand of engine oil Increased clearances between piston pins and bores in piston bosses Increased clearances between the connecting rod journals of the crankshaft and liners The axes of the upper and lower connecting rod heads are not parallel Piston installed incorrectly (Piston pin bore offset towards left side of engine) | Adjust alternator belt tension or replace See above «Increased noise of the gas distribution mechanism» Change engine oil to recommended Replace pistons and piston pins Replace bearings and grind crankshaft journals Replace connecting rod Install the correct piston |
Strong knocking in a warm engine with an increase in the crankshaft speed | |
Vibration damper failure in the crankshaft pulley hub Excessive tension of the alternator drive belt or the appearance of cracks and breaks on it Loose flywheel Excessive increase in clearances between the shells of the connecting rod and main bearings of the crankshaft | Replace crankshaft pulley Adjust alternator belt tension, replace damaged alternator belt Tighten the flywheel mounting bolts to the required torque Regrind the crankshaft journals to the repair size and replace the liners |
Increased engine vibration | |
Crankshaft imbalance Installed pistons of different weights Valve clearances broken Unequal compression values in the cylinders Powertrain suspension pads severely worn or hardened Loose crankshaft pulley | Remove and balance the crankshaft Disassemble the connecting rod and piston group, select the pistons by weight Adjust valve clearances (see «Valve clearance adjustment») Cm. «Cylinder compression check» Replace engine mounts Tighten the crankshaft pulley |
Engine knock noises when under load | |
Using low octane gasoline Faulty knock sensor Faulty ECU (electronic control unit) engine | Fill with gasoline with the correct octane rating Replace knock sensor Replace ECU (electronic control unit) engine |
Increased oil consumption | |
Oil leakage through engine seals Clogged crankcase ventilation system Worn piston rings or engine cylinders Breakage of piston rings Coking of oil scraper rings or grooves in the piston grooves due to the use of non-recommended oil Worn or damaged valve stem seals Increased wear on valve stems or guide bushings | Tighten fasteners or replace gaskets and seals Flush the parts of the crankcase ventilation system Rebore cylinders and replace pistons and rings Replace piston rings Clean the rings and grooves from carbon deposits, replace the engine oil with the recommended Annex 3 Replace 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 soiled Faulty thermostat Faulty engine cooling fan Expansion tank plug valve defective (permanently open, causing the system to be at 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 components Replace expansion tank cap Fill with gasoline with the correct octane rating |
Rapid drop in fluid level in expansion tank | |
Damaged radiator Damage to hoses or gaskets in pipe connections, loose clamps Fluid leakage through the water pump seal Damaged cylinder head gasket Fluid leakage through microcracks in the block or cylinder head | Repair or replace radiator Replace damaged hoses or gaskets, tighten hose clamps Replace water pump Replace cylinder head gasket Check the tightness of the block and cylinder head, if cracks are found, replace damaged parts |