Odisha CHSE VOC-ITV Four Wheeler Service Technician common mistakes
Odisha CHSE VOC-ITV Four Wheeler Service Technician · Understand the traps and how to avoid them.
On a cylinder-head or wheel-nut question, the candidate specifies tightening fasteners in a circle and judges tightness by feel or by using an open-end spanner with a pipe extension instead of stating a calibrated torque wrench and the manufacturer's sequence.
Workshop habit treats 'tight' as a single sensation, and candidates memorise component names without memorising torque values, sequences, or the fact that a torque wrench must be zeroed and within calibration.
What to do instead
For every bolted joint you revise, write down three things together: torque value with unit (N·m), tightening sequence (spiral/star from centre outward for a head; alternate opposite nuts for a wheel), and the tool (calibrated torque wrench, correct socket). Practise stating that a torque wrench is checked against its calibration certificate and returned to zero after use.
When asked to set valve clearance, the candidate rotates the engine to TDC but does not confirm the compression stroke, then sets clearance on a cylinder whose valves are on overlap; or applies a hot-engine clearance figure to a cold engine.
TDC marks on the crank pulley are seen as 'the' setting position, and candidates do not connect the four-stroke cycle to which rocker arms should be free. Cold/hot specifications get mixed because both numbers appear in the manual.
What to do instead
Always state the check: with the engine at TDC on the firing stroke for cylinder 1, both pushrods should spin freely and both rockers should have clearance. Use the feeler gauge of the specified thickness, note whether the manual gives cold or hot clearance, and adjust with the rocker screw and locknut while holding the feeler gauge with a slight drag. Recheck after rotating two full turns.
Faced with a diesel hard-start or rough-running complaint, the candidate immediately writes 'replace injectors' or 'overhaul injection pump' without first checking fuel filter restriction, air in the fuel line, glow-plug operation, battery cranking voltage, and rail pressure or injector leak-off.
Injectors and pumps are the visible, expensive parts, so they attract blame. Candidates also skip the cheap upstream checks because those require a test sequence rather than a parts swap.
What to do instead
Answer in a fixed order: battery and cranking speed, fuel quality and filter, air ingress at the filter housing and primer, glow plugs (if fitted), then rail pressure during cranking and injector leak-off/back-leak test. Only after these are normal should injector replacement be considered. Write the sequence as a numbered list in your revision notes so it becomes automatic.
The candidate describes filling the cooling system with plain water or topping up to the brim, and describes filling engine oil until it reads above the maximum mark 'to be safe', without mentioning bleeding air or checking the dipstick after running.
Coolant and oil are treated as 'just fluids', and overfilling is assumed to be harmless. Air pockets and the difference between the dipstick marks and total capacity are not linked to overheating or seal failure.
What to do instead
State the correct practice: use the specified coolant mixed to the manufacturer's ratio with clean water, fill slowly, run the engine with the heater on and the radiator cap off until the thermostat opens and the level stabilises, then top up to the mark. For oil, fill to the dipstick range, run, stop, wait, and recheck; overfill causes aeration and seal leakage, underfill causes starvation.
When refitting a clutch, the candidate fits the disc without checking the 'flywheel side' marking and without a clutch alignment tool, then forces the gearbox back with the bell-housing bolts. On propeller shafts, the candidate refits the shaft without matching the yoke phase or marks.
The disc looks symmetrical, and alignment tools are often missing in the workshop, so force replaces alignment. Propeller-shaft phasing is invisible once the shaft is bolted up, so it is forgotten.
What to do instead
Before assembly, identify the disc marking and place that side toward the flywheel; use a pilot shaft or alignment tool and tighten the pressure plate evenly and progressively. Mark the shaft and flange before removal, refit in the same spline position, and ensure universal-joint yokes are in phase. After fitting, rotate by hand and confirm the disc is centred before bolting the gearbox.
The candidate tightens wheel nuts in a continuous circle and with a wheel brace, and confuses wheel alignment with wheel balancing, stating that a shimmy at speed is cured by 'alignment'.
Wheel nuts are treated as a simple 'tighten all round' task, and alignment and balancing both sound like 'wheel work'. The symptom pattern (shimmy at a road speed versus pull or off-centre steering) is not learned.
What to do instead
Tighten wheel nuts in a star or alternate pattern in two stages, finishing with a torque wrench at the specified value. Separate the diagnoses clearly: balancing corrects vibration or shimmy at a particular speed and is done on a balancing machine; alignment corrects pull, off-centre steering wheel, or uneven tyre wear and is set with camber, caster, and toe figures. State this distinction in one sentence in your notes.
When bleeding brakes, the candidate holds the pedal down while the bleeder is opened and then releases the pedal before closing the bleeder, drawing air back into the system; or tops up with an unknown brake fluid and mixes DOT grades.
The pumping action is copied by observation rather than understood as a pressure-and-close sequence, and brake fluid containers are not checked because 'brake fluid is brake fluid'.
What to do instead
Describe the correct sequence: fill the reservoir, start at the wheel farthest from the master cylinder, attach a clear tube to the bleeder into a container, have an assistant press and hold the pedal, open the bleeder, close it before the pedal is released, and repeat while checking the reservoir level. Use only the fluid grade specified on the cap, from a sealed container, and never reuse drained fluid.
To test the charging system, the candidate disconnects a battery terminal with the engine running to see whether the engine keeps running; or uses a low-impedance test lamp or ohmmeter across electronic circuits instead of a voltmeter and voltage-drop test.
This is a widely repeated roadside trick, and it appears to give a quick yes/no answer. The damage it causes to the alternator and electronic control units is not visible during the test.
What to do instead
State that the battery stays connected. Test charging with a multimeter across the battery: about 12.6 V engine off, 13.5–14.5 V at fast idle with loads on. Use a carbon-pile load tester if specified. For circuit faults, measure voltage drop with the circuit loaded rather than resistance with the circuit off, and use a high-impedance digital multimeter.
The candidate treats a stored diagnostic trouble code as a direct component verdict, for example replacing spark plugs because P0300 is stored, or replacing an oxygen sensor because a mixture code appears, without checking freeze-frame data, live data, or the enabling conditions.
Codes are easy to read and are memorised as fault names. The difference between a code that reports a symptom and a test that confirms a failed part is not reinforced.
What to do instead
Use a three-step answer: record the code and freeze-frame, verify the complaint and reproduce it, then test the circuit or component the code points to. For a random misfire, check ignition, fuel trim, intake leaks, and compression before parts. State clearly that a code is a starting point, not a diagnosis.
In a servicing or inspection question, the candidate jacks the vehicle under the floor pan, side sill, or suspension arm instead of the designated jacking points, and starts work without a pre-service road test, without recording the customer's complaint, and without fitting fender covers.
Jacking points are assumed to be 'anywhere strong', and the service routine is remembered as an oil change rather than a documented sequence with a road test and customer concern.
What to do instead
Learn the jacking and axle-stand points for the vehicle layout and state that stands are placed under the axle or chassis before anyone goes underneath. Use a standard routine: record the complaint, road-test and note symptoms, protect the vehicle, inspect, service, recheck, and road-test again. State the purpose of each step, not just its name.