NANO

ENGINE 273 MPFI

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

) 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.