ENGINE 24 2.1.2 MAINTENANCE, INSPECTION AND TESTS: 2.1.2.1 PRELIMINARY INSPECTION: NOTE It is always advisable to first use the diagnostic tool and rectify the electrical faults, before commencing with mechanical repairs/ troubleshooting. Refer EMS section in this group for procedure. GENERAL • Check for leakage of Oil, fuel, and Coolant. • Check for overheating of engine. • Check for unusual smoke. • If there is any fault in the Engine Management system (EMS) then the MIL indicator in the instrument cluster will come ON. In such a case connect the diagnostic tester. (For procedure refer EMS section). Before proceeding to carry out actual reconditioning of engine, it is desirable to have a preliminary inspection of engine to ascertain whether an engine reconditioning is necessary and if so, to what extent. Most common reasons for which engine is reconditioned are 1. Loss of power. 2. Excessive engine oil consumption. 3. Extremely 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. EMS is in limp-home mode due to some critical fault. b. Clogged air filter / clogged intercooler fins /loss of charge air pressure / choked exhaust passage / catalytic converter. c. Loss of engine compression d. Defective fuel system e. Clutch slippage f. Brake binding A. EMS is in limp-home mode If the EMS detects some major fault in the system it switches to limp-home mode, where it runs at a reduced torque. Connect the diagnostic tester and check if any faults are present in the Engine EMS, if found rectify them. (For details refer Engine Management Section) B. Clogged Air filter/Loss of Charge Air Pressure/ Choked exhaust system. Loss of power indicates lack of air or low air charging pressure to engine cylinders. Clean air filter & inter cooler fins. Check all joints for air leakage. If power loss still felt, check exhaust system for choking, rectify if ON as per procedure mentioned in owner’s manual. Clean and replace silencer if necessary. Check for kink formation in exhaust piping. C. 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, check engine compression as follows. • Warm up engine preferably by road drive to get a coolant temperature of about 90ºC. Stop the engine. • Remove the air filter. • Remove the injector back-leak pipes and high pressure pipes from rail to injector .Disconnect rail pressure sensor. • Plug the common rail outlet with suitable caps. • Remove all injectors. • Fit adapter (Part no 2868 5890 07 01) in place of one injector. • Connect compression tester to adapter and tighten vent knob. • Crank the engine with starter motor by 200-350 rpm approximately. Pressure gauge needle will start rising. Continue cranking till gauge needle stops rising any further. Note down the 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 23 ± 1 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, leakage past the valves is indicated. If compression pressure of adjacent cylinder is al-
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