Automotive Servicing NC I cheat sheet

OHS hierarchy of control, most to least effective: elimination, substitution, engineering controls, administrative controls, then PPE.

PPE is the last line of defence; it does not remove the hazard and requires training, fit checks, and maintenance records.

Near-miss reporting is a leading indicator; incidents without injury are recorded and investigated the same way as injury cases.

Manual handling rule: keep the load close to the body, bend knees not the back, and get help above roughly 25 kg or when the load is awkward.

Job hazard analysis (JHA) breaks a task into steps, identifies hazards per step, and assigns controls before work starts.

Emergency response sequence: raise the alarm, secure the area and isolate energy, give first aid within training limits, then report and document.

Workplace communication uses the 5W1H structure for reports: what, where, when, who, why, how; verbal instructions are confirmed by repeat-back.

Hazardous waste such as used oil, coolant, and batteries is segregated, labelled, and turned over to an authorised collector; never to drains or general refuse.

Fire classes decide the extinguisher: A solid combustibles, B flammable liquids, C flammable gases, D metals, E electrical (in some classifications), K cooking oils.

Vernier caliper reading: main scale value plus (coinciding vernier division multiplied by least count); a 0.02 mm caliper has 50 vernier divisions.

Micrometer reading: sleeve reading plus thimble reading; a 0.01 mm metric micrometer advances 0.5 mm per revolution of the spindle.

Torque wrench: set to the specified value, apply force smoothly to the handle, never use it to loosen fasteners, and recalibrate periodically.

Feeler gauge measures clearance by the blade that fits with slight drag; the next size up must not enter.

Dial indicator and magnetic base measure runout, end play, and backlash; the plunger must be perpendicular to the measured surface.

A micrometer zero check uses the spindle and anvil closed on each other; any error is noted and the instrument is recalibrated or replaced.

Tool safety rules: pull a wrench, never push; use the correct size to avoid rounding; keep cutting edges sharp; never extend a wrench with a pipe.

Precision instruments are stored clean and lightly oiled, away from moisture and magnetic fields, and are not used as hammers or pry bars.

Workshop equipment such as a hydraulic press or bench grinder requires guarding, a pre-use inspection, and a clearance zone before operation.

PMS intervals follow the manufacturer schedule, typically by distance or time, whichever comes first; severe-duty use shortens the interval.

Engine oil level check: engine off and level ground, wipe the dipstick, reinsert fully, read between the low and full marks.

Tyre pressure is checked cold; a difference of about 1 psi per 10 degrees F change is expected, and the spare is included in the check.

Tread depth limit is 1.6 mm; measure in the main grooves at several points and check for uneven wear indicating alignment or inflation faults.

Battery check: open-circuit voltage around 12.6 V for a fully charged 12 V battery; a load test confirms cranking capacity.

Coolant level is checked at the reservoir when cold; never open a hot pressurised radiator cap.

Brake fluid is hygroscopic; dark colour and a moisture test above roughly 3 percent indicate replacement is due.

Belt tension and condition: check for glazing, cracks, and fraying; a deflection specification or tension gauge is used, not guesswork.

Road test inspection covers steering free play, brake response, unusual noise, vibration, and instrument warning lamps.

Four-stroke cycle order: intake, compression, power, exhaust; the crankshaft completes two revolutions per full cycle.

Firing order and valve timing are set by marks on the crankshaft pulley and camshaft sprocket; align marks before removing a timing belt.

Compression test: throttle wide open, all plugs removed, engine cranked a set number of strokes; a low cylinder is rechecked wet with oil to distinguish rings from valves.

Valve clearance (tappet) is measured cold with a feeler gauge between the cam and follower and adjusted to the manufacturer specification.

Engine oil pressure low causes: low oil level, worn pump, blocked pickup, incorrect viscosity, faulty relief valve, or worn bearings.

Overheating causes: low coolant, faulty thermostat, failed water pump, blocked radiator, inoperative cooling fan, or a blown head gasket.

Serpentine belt routing is recorded before removal and matched to the under-bonnet diagram; tension is set by an automatic tensioner.

Engine mounts are checked for cracked rubber and separation; excessive movement shows as clunking on acceleration or deceleration.

Timing belt replacement follows distance or age; a broken belt on an interference engine causes valve and piston contact.

Ohm's law: V equals I times R; power in watts equals volts times amps; use these to size fuses and diagnose voltage drop.

Series circuit: current is the same everywhere, voltage divides; parallel circuit: voltage is the same, current divides.

Battery voltage of 12.6 V indicates full charge; below 12.4 V is partially discharged; charging voltage from the alternator is typically 13.5 to 14.5 V.

Voltage drop testing locates resistance: measure across the circuit under load; more than about 0.5 V on a main cable indicates a fault.

A fuse protects the circuit; replace with the same rating, never higher; a blown fuse points to a short or overload to be found.

Relays and solenoids use a small control current to switch a large load current; test coil resistance and contact continuity separately.

Starter circuit: battery, cables, solenoid, and starter motor; slow crank with dim lights suggests cable or battery, rapid clicking suggests low battery or solenoid.

Alternator charging test: engine running, measure battery terminal voltage and check for AC ripple, which indicates a failed diode.

Electronic control units read sensors and drive actuators; diagnosis starts with the fault code, then a wiring and connector check before part replacement.

Brake pedal free play is adjusted at the pushrod; excessive free play causes a low pedal, too little causes brake drag and overheating.

Brake bleeding order removes air, usually starting at the wheel farthest from the master cylinder; the reservoir must not run dry.

Brake pad minimum thickness is typically around 2 mm of friction material; discs are measured for thickness and runout against specification.

Steering wheel free play of roughly 25 to 50 mm at the rim is normal; more indicates wear in the box, linkages, or tie-rod ends.

Toe setting is measured in mm or degrees; positive toe is toe-in, negative is toe-out; incorrect toe causes rapid or feathered tyre wear.

Caster affects straight-line stability, camber affects tyre wear and grip, and both are checked after suspension repair.

Shock absorber test: bounce the corner and release; more than one rebound indicates a worn damper; check for leaks and loose mounts.

Wheel bearing play is checked by rocking the wheel at 12 and 6 o'clock; noise that changes with cornering load indicates a bearing fault.

Hydraulic brake system components: master cylinder, lines, proportioning valve, caliper or wheel cylinder, and the bleeding points.

Clutch operation: pedal releases the pressure plate, the disc disengages, and drive is interrupted; free play is set at the release mechanism.

Clutch slip shows as engine speed rising without vehicle speed; judder indicates a warped or contaminated disc; noise on pedal press points to the release bearing.

Manual gearbox oil is checked at the filler or level plug with the vehicle level; the oil should be at the bottom edge of the hole.

Automatic transmission fluid is checked per manufacturer procedure, often with the engine running at operating temperature in the specified range.

CV joint diagnosis: a clicking noise on full lock indicates a worn outer joint; vibration under acceleration suggests an inner joint or shaft imbalance.

Differential backlash and tooth contact pattern are checked with marking compound after reassembly; incorrect backlash causes whine and rapid wear.

Driveshaft universal joints are checked for play and grease fittings serviced; a seized joint causes vibration and can damage the yoke.

Final drive ratio equals ring gear teeth divided by pinion teeth; a change in ratio affects speedometer accuracy and acceleration.

Gear selection faults: hard shifting with the engine off points to linkage; with the engine running, suspect the clutch or synchronisers.