ENGINE 18 PRELIMINARY INSPECTION OF ENGINE Before proceeding to carry out actual reconditioning of engine it is desirable to have a preliminary inspection of engine to ascertain whether an engine recondition is necessary and to what extent. Most common reasons for which engine is reconditioned are : 1. Loss of power 2. Excessive engine oil consumption. 3. Excessive low engine oil pressure 4. Mechanical failures To know exact reason and general condition of engine, proceed as follows : 1. LOSS OF POWER Loss of engine power may be due to : a. Clogged air cleaner / loss of charge air pressure / choked exhaust silencer b. Clutch slippage c. Brake binding d. Defective fuel injection system e. Loss of engine compression a. CLOGGED AIR CLEANER / LOSS OF CHARGE AIR PRESSURE / CHOCKED EXHAUST SILENCER Loss of power indicates lack of air or low air charging pressure to engine cylinders. Loss of charge pressure can be due to leakage of charge air from outlet of turbocharger, worn out vanes of turbocharger, compressor & leakage in the inlet manifold etc. Clean air filter. Check all joints for air leakage. If power loss with black smoke is still felt, check exhaust silencer and catalytic converter for choking. Clean and replace silencer/catalytic converter if necessary. b. CLUTCH SLIPPAGE Clutch slipping can be confirmed by any of the following two methods : Drive vehicle in 1st and 2nd gear at maximum speed corresponding to that gear. With accelerator pedal fully pressed, apply brake gradually with left foot. If the engine stalls it means that clutch does not slip. Drive loaded vehicle in 3rd gear on level ground and let the speed drop down to approximately 15 kmph. Now press accelerator pedal fully. With slipping clutch the vehicle speed will not pick up and also clutch burning smell will be noticed. If this does not occur and vehicle picks up speed, it indicates that clutch does not slip. c. BRAKE BINDING During driving apply brakes number of times and then shift gear to neutral position check brake drums/brake discs for overheating and if necessary jack up axles and check wheels for free rotation. Check hand brake position (Released or applied) d. FUEL INJECTION SYSTEM Check condition of fuel filters for clogging, low pressure fuel lines for any leakages. If check engine lamp comes ''ON'' follow the diagnostics procedure. e. CHECKING ENGINE COMPRESSION PRESSURE - If loss of power is not on account of defective fuel system, lack of air, choked exhaust system, clutch slipping and brake binding, then Check engine compression as follows. - Warm up engine preferably by road drive to get a temperature of about 85o to 95o C. Remove all injectors. Flame guard washers should be replaced while refitting the injectors. - Fit adaptor in place of one injector. - Connect compression tester to adaptor and tighten vent knob. - Crank engine with starter motor by 200-350 rpm approx. Pressure gauge needle will start rising. Continue cranking till gauge needle stops rising any further. Note down reading. Loosen vent knob to make sure the tester needle returns to zero. Repeat this operation for remaining cylinders. - Minimum compression pressure in each cylinder should be 16 bar. Variation in compression pressure between cylinders should not be more than 1.5 bar. - Low compression pressure may be due to leakage past valves / piston rings /blown cylinder head gasket. To ascertain the point of leakage, spray small quantity of clean engine oil in to cylinder showing low pressure. If it improves, wear in piston rings / cylinder bore is indicated. If it does not, leakagepast thevalves is indicated. If compression pressure of adjacent cylinder is also on lower side
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