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13
4 DLT ENGINE
PRELIMINARY INSPECTION OF ENGINE
B
efore 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.
M
ost 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 system
e.
Loss of engine compression
a. CLOGGED AIR CLEANER / LOSS OF CHARGE
AIR PRESSURE / CHOCKED EXHAUST
SILENCER
L
oss of power with unusual black smoke from engine
exhaust 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.
C
lean air cleaner. 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 :
D
rive 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.
D
rive 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 SYSTEM
C
heck condition of fuel filter elements, fuel
injection timing, injection nozzles and fuel
injection pump for proper functioning.
e. CHECKING ENGINE COMPRESSION
PRESSURE
-
I
f loss of power is not on account of defective fuel
system, lack of air, choked exhaust system, clutch
slipping and brake binding.
C
heck engine compression as follows.
- Warm up engine preferably by road drive to get a
temperature of about 85
o
to 95
o
C.
R
emove all injectors. Flame guard washers should
be replaced while refitting the injectors.
-
F
it adaptor 2654 5890 01 01 in place of one injector.
Tighten pressure screw using spanner 312 589 00
09 to specified torque.
-
C
onnect compression tester to adaptor and tighten
vent knob.
-
C
rank 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.
-
M
inimum compression pressure in each cylinder
should be 19 bar. Variation in compression
pressure between cylinders should not be more
than 1.5 bar.
-
L
ow compression pressure may be due to leakage
past valves / piston rings /blown cylinder head