NANO

ENGINE 273 MPFI 83 ENGINE COMPRESSION PRESSURE CHECKING PROCEDURE • Warm up engine preferably by road drive to attend a temperature of about 75 °C to 85 °C. • Remove fuel connection to fuel rail (after relieving fuel pressure as indicated in fuel section) & suitably prevent fuel from spilling from open connection. • Remove one of the spark plug whose compression is to be check. (Refer Engine group for spark plug removal procedure) • Install Compression gauge (Range about 0 to 25 kg/cm 2 ) into one of the spark plug hole. NOTE Use adaptor if required which is commercially available to suit the size of the spark plug threads . • Press the clutch pedal to disengage clutch (to reduce starting load on engine) and depress accelerator pedal all the way to make throttle valve open fully. • Disconnect ECU. • Crank engine with fully charged battery, and read the highest pressure on compression gauge. • Carry out above steps on remaining cylinder to obtain compression pressures. The specified compression pressure is 12 to 13 bar minimum. • Variation in compression pressure between cylinders should not be more than 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 the cylinder showing low pressure and recheck compression 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 also on lower side, it may be due to blown cylinder head gasket.