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Inspection, Disassembly, Assembly, Adjustment, and Repair

Automobile Maintenance · 自動車整備分野 · Written by Tokutei Pass based on the official study texts; not copied verbatim.

Daily Inspection (15 Items) and Periodic Inspection Basics

To ensure safe driving and prevent pollution, the Road Transport Vehicle Act mandates Daily Inspection and Periodic Inspection. Daily inspection for private passenger cars consists of 15 items, carried out at appropriate times judged from mileage and operating conditions, such as before a long drive (commercial vehicles and rental cars must be inspected once every day before operation).

(1) The 5 items inspected by looking inside the engine compartment are: Window washer fluid level, Brake fluid level, Battery electrolyte level, Coolant level (in the reservoir tank), and Engine oil level.

Pull out the engine oil dipstick (oil level gauge) once, wipe it clean with a rag, insert it all the way back in, and pull it out again to check that the oil level is between the upper limit (F/MAX) and lower limit (L/MIN).

(2) The 4 items inspected by walking around the vehicle are: Tire inflation pressure, Presence of tire cracks or damage, Tire tread depth (abnormal wear), and Lighting / flashing, dirt, or damage of lamps.

(3) The 6 items inspected while sitting in the driver's seat are: Brake pedal clearance when depressed and braking effectiveness, Parking brake lever pull (or pedal) stroke, Window washer spray condition, Wiper wiping condition, Engine starting condition and abnormal noise, and Engine low-speed and acceleration condition.

Furthermore, periodic inspections for private passenger cars include the 1-year inspection (12-month inspection) and the 2-year inspection (24-month inspection).

Daily Inspection (15 Items) and Periodic Inspection Basics

Key points


  • The 15 daily inspection items consist of 5 engine room items (fluid levels), 4 walk-around items (3 tire items + lamps), and 6 driver's seat items (brakes, visibility, engine condition)

  • Check engine oil level with the engine stopped by wiping the dipstick once, inserting it fully, and verifying the level is between the upper and lower marks

  • Periodic inspections for private passenger cars are conducted every 1 year (12 months) and every 2 years (24 months)
WordMeaning
Daily inspection (15 items) (Mandatory pre-operation / routine check covering 5 engine room, 4 exterior, and 6 cabin items)
Periodic inspection (12-month and 24-month inspection) (Statutory regular maintenance inspections conducted every 1 and 2 years)
Oil level gauge (dipstick) (Rod used to check that engine oil level sits between L/MIN and F/MAX)
Reservoir tank (Translucent tank allowing visual inspection of coolant or brake fluid level)

Basic Rules of Disassembly / Assembly and Non-Reusable Parts

When disassembling engine or chassis parts, check existing mating marks (alignment marks) or make new ones before disassembly so that original positions, orientations, and rotational balance are not lost during reassembly. Also, arrange removed pistons, valves, and bearings in cylinder-number order so they do not get mixed up.

Parts that must never be reused once disassembled and removed—and must always be replaced with new ones even if they look undamaged—are called non-reusable parts. Typical examples include sealing parts such as gaskets, packings, O-rings, and oil seals, as well as locking parts such as cotter pins (split pins) and clawed lock washers.

When installing a new O-ring or oil seal, apply a thin coat of engine oil or specified grease to the lip (sealing edge) and press it in straight so the lip is not twisted or damaged.

Furthermore, when inserting a new cotter pin into a castle nut (slotted nut), after tightening to the specified torque, if the pin slots do not align with the bolt hole, turn the nut further in the tightening direction to align them (never back it off in the loosening direction).

Before assembly, clean all parts, blow out dust from oil passages with compressed air (air blow), and always apply fresh engine oil to sliding surfaces—such as pistons, cylinders, and bearings—before assembly to prevent initial scuffing or seizure.

Key points


  • Before disassembly, place mating marks so installation position and balance are preserved, and organize removed parts in cylinder order

  • Gaskets, packings, O-rings, oil seals, and cotter pins are non-reusable parts and must always be replaced with new ones upon disassembly

  • Apply oil or grease to sliding parts and the lips of O-rings and oil seals before assembly to prevent damage and initial seizure
WordMeaning
Mating mark (alignment mark) (Reference mark placed prior to disassembly to ensure exact reassembly alignment)
Non-reusable parts (gaskets, O-rings, cotter pins) (Single-use components that must always be replaced with new parts when removed)
Oil seal (Rotary shaft seal whose lip must be lubricated before installation)
Castle nut (slotted nut) (Nut with slots secured against loosening by passing a new cotter pin through)

Tightening Sequence of Critical Bolts and Nuts (Cylinder Head / Wheels)

For components where a wide surface is fastened by many bolts, such as a cylinder head, using the wrong loosening or tightening sequence causes cylinder head warpage (distortion), resulting in gas or water leaks.

When tightening cylinder head bolts (during assembly), always work from the center (inside) toward the outside in a diagonal criss-cross pattern, tightening evenly a little at a time in 2 to 3 stages, and finish to the specified torque with a torque wrench (or angle tightening).

Conversely, when loosening cylinder head bolts (during disassembly), work in the opposite order—from the outside toward the inside (center)—loosening gradually in several stages. Never loosen one bolt completely at a time or loosen from the inside out.

Additionally, when mounting a tire (disc wheel), orient the wheel nuts so the tapered (cone-shaped) seat faces inward (toward the wheel).

Rather than tightening adjacent nuts in a circle, snug-tighten them in 2 to 3 stages in a diagonal (star) pattern, lower the tire to the ground, and perform final tightening to the specified torque with a torque wrench (in principle, do not apply oil or grease to the threads as it causes over-torquing).

Tightening Sequence of Critical Bolts and Nuts (Cylinder Head / Wheels)

Key points


  • When tightening cylinder head bolts, tighten evenly in 2 to 3 stages in order from the center (inside) toward the outside

  • When loosening cylinder head bolts (disassembly), work in reverse from the outside toward the inside (center) in several stages

  • Orient wheel nuts with the tapered portion facing inward (wheel side), tighten in a diagonal (star) sequence, and finish to specified torque with a torque wrench
WordMeaning
Cylinder head bolt (Tighten from center outward; loosen from outside inward)
Warpage (distortion) prevention (Reason for multi-stage symmetrical loosening and tightening sequences)
Wheel nut (tapered seat) (Conical seat of the lug nut that centers the wheel; must face inward)
Diagonal (star) sequence (Criss-cross tightening order used on wheels and multi-bolt flanges)

Adjustment Work, Brake Air Bleeding, and Oil Change Procedures

When adjusting engine valve clearance, first turn the crankshaft pulley to set the #1 cylinder piston at top dead center (TDC) on the compression stroke, and use a thickness gauge to measure and adjust the valves whose rocker arms are free at that position.

Next, rotate the crankshaft 1 full turn (360 degrees) to set the #4 cylinder (in a 4-cylinder engine) at compression TDC, and adjust the remaining valves.

When changing engine oil and the oil filter, after draining old oil from the drain plug, replace the drain gasket (washer) with a new one and tighten the drain plug.

When installing a new oil filter, apply a thin coat of clean engine oil to the O-ring, screw the filter in by hand until the seal contacts the mounting surface, and then tighten it by the specified number of turns (or specified torque).

After disassembling hydraulic brake lines or cylinders, air bleeding (bleeding the brakes) is always required to expel air that entered the lines. Top up brake fluid in the reservoir tank, and in principle start from the bleeder plug of the wheel cylinder farthest from the master cylinder.

Air bleeding is performed by a two-person team. While one person pumps the brake pedal several times and holds it firmly depressed, the other person loosens the bleeder plug to let bubbly brake fluid escape through a vinyl hose, then tightens the bleeder plug while the pedal is still held down before letting the pedal return. Repeat this until no air bubbles appear.

Adjustment Work, Brake Air Bleeding, and Oil Change Procedures

Key points


  • To adjust valve clearance on a 4-cylinder engine, set cylinder #1 to compression TDC to adjust half the valves, then turn the crankshaft 1 revolution (360 degrees) to adjust the rest

  • When replacing the oil filter, coat the new filter's O-ring with engine oil before installation, and check for oil leaks after starting the engine

  • During brake air bleeding, watch the reservoir fluid level so it does not run dry, loosen the bleeder plug with the pedal held down, and tighten the plug before releasing the pedal until bubbles stop
WordMeaning
Top dead center (TDC) on compression stroke (Piston position where both intake and exhaust valves are closed for valve adjustment)
Drain gasket (Sealing washer on the oil pan drain plug that should be replaced at oil changes)
Air bleeding (brake bleeding) (Procedure for purging trapped air bubbles from hydraulic brake lines)
Bleeder plug (bleeder screw) (Valve on a wheel cylinder or caliper opened to expel air and fluid)

Pass / Fail Judgment and Calculations Using Standard Values and Service Limits

In the judgment and planning sections of the practical exam, questions always require comparing a measured value against the service manual's standard value and service limit (limit value) to determine whether a part is Good (Pass: reusable as-is) or Defective (Fail: requires repair or replacement).

Pattern 1 covers parts whose thickness or depth decreases (gets smaller) as they wear.

For brake pad thickness, brake shoe lining thickness, brake disc rotor thickness, tire tread depth, engine compression pressure, and battery specific gravity, the service limit is defined as a lower limit (minimum allowable value). Therefore, if Measured value < Service limit, the part is judged Defective (replace).

Pattern 2 covers parts whose clearance or runout increases (gets larger) due to wear or deformation.

For cylinder bore diameter, piston ring end gap, oil clearance, shaft bend, disc rotor runout, cylinder head warpage, and brake drum inside diameter, the service limit is defined as an upper limit (maximum allowable value). Therefore, if Measured value > Service limit, the part is judged Defective (replace).

Furthermore, for items specified by a standard value range (e.g., 0.15~0.25 mm) such as valve clearance, fan belt deflection, pedal free play, toe-in, and idling speed, if the measured value falls outside the range, judge that adjustment is required.

Key points


  • Because brake pad thickness, disc thickness, and tire tread depth decrease with wear, judge Replace (Defective) when Measured value < Service limit (lower limit)

  • For brake drum inside diameter, shaft bend, disc runout, head warpage, and oil clearance, judge Replace (Defective) when Measured value > Service limit (upper limit)

  • Example: When brake pad standard thickness is 10.0 mm and the service limit is 2.0 mm, a vernier caliper reading of 1.5 mm is below the service limit (2.0 mm), so judge Defective (replace pad)

  • Example: When the shaft bend service limit is 0.03 mm and dial gauge runout over 1 turn on V-blocks is 0.08 mm, bend = 0.08 / 2 = 0.04 mm, which exceeds the limit (0.03 mm), so judge Defective (replace)
WordMeaning
Standard value (Nominal specification of a new or properly adjusted component)
Service limit (wear limit) (Maximum or minimum permissible threshold before repair or replacement is required)
Wear amount (Difference between the original standard dimension and the measured dimension)
Pass / fail judgment (Evaluating whether a measured value satisfies the service limit)

Fundamentals of Troubleshooting (Fault Diagnosis)

In the practical exam and shop troubleshooting, possible causes are narrowed down systematically from symptoms. For example, if the starter does not crank at all, inspect for a dead battery (low terminal voltage or specific gravity), loose or corroded battery terminals, the AT inhibitor switch (shift lever not in P or N), or a faulty starter motor.

If the starter cranks briskly but the engine does not start, check the three essential elements of an engine in order: Good air-fuel mixture (fuel), Good compression, and Good spark (ignition). Check for an empty fuel tank, inoperative fuel pump, spark plug firing, or loss of compression due to a broken timing belt.

If the engine overheats, check for coolant (LLC) leakage or shortage, loose or broken fan belt, thermostat stuck closed, inoperative electric cooling fan, clogged radiator core, or faulty radiator cap pressure valve.

If braking is poor or the brake pedal goes down too far, suspect brake fluid leakage, air trapped in the brake lines, worn brake pads or linings, or fade / vapor lock on a long downgrade.

In addition, connecting an external diagnostic tester (scan tool) to the on-board diagnostic system (OBD) allows reading diagnostic trouble codes (DTCs) stored in the ECU.

Key points


  • If the starter does not crank, check battery voltage, loose terminals, and the inhibitor switch; if it cranks but will not start, check the 3 elements: Fuel, Ignition, and Compression

  • Major causes of overheating include insufficient coolant, loose or broken fan belt, thermostat stuck closed, and faulty electric fan

  • Connecting a scan tool (external diagnostic tester) to the vehicle's DLC (data link connector) enables reading and clearing diagnostic trouble codes (DTCs) detected by the ECU
WordMeaning
Inhibitor switch (Safety switch on AT vehicles that permits starter operation only in P or N)
Overheat (Abnormal rise in engine temperature caused by cooling system failure)
Scan tool (external diagnostic tester) (Handheld tester plugged into the DLC to read ECU fault codes and live data)
Diagnostic trouble code (DTC) (Malfunction code recorded by the ECU when a sensor or actuator fault occurs)

Structure and Passing Criteria of the Specified Skilled Worker (i) Auto Maintenance Exam

The Automobile Repair and Maintenance Specified Skilled Worker (i) Evaluation Exam verifies whether candidates possess the foundational knowledge and skills (equivalent to Japan's Class 3 Automotive Mechanic) to independently and properly perform daily inspections, periodic inspections, and disassembly maintenance assistance in Japanese automotive repair shops.

The exam consists of both a Written Exam and a Practical Exam, held consecutively on the same day for a total of 80 minutes (via CBT computer testing or paper testing). As a rule, exam questions are written in Japanese with furigana readings provided on all kanji.

(1) Written Exam: Consists of 30 questions, all in True / False format. Testing time is 60 minutes, and the passing score is 65% or higher (at least 20 correct answers out of 30). Questions cover the entire syllabus evenly: structure, function, tools, materials, and inspection/maintenance.

(2) Practical Exam (Judgment Test and Planning Test): A two-choice paper (or CBT) practical test answered by inspecting illustrations and photographs.

It consists of 3 major sections × 3 questions each = 9 questions in total, with a testing time of 20 minutes and a passing score of 60% or higher (guideline: 6 or more correct answers). Note that individuals who have passed the Class 3 or higher Automotive Mechanic Skills Certification or satisfactorily completed Technical Intern Training (ii) in automobile maintenance are exempt from this evaluation exam.

Key points


  • The Specified Skilled Worker (i) Evaluation Exam takes 80 minutes in total—Written Exam (60 min) plus Practical Exam (20 min)—and is given in Japanese with furigana

  • The Written Exam has 30 True/False questions (passing standard: 65% or higher = 20+ correct), and the Practical Exam has 9 two-choice questions using diagrams/tables (passing standard: 60% or higher)

  • Holders of a Class 3 Automotive Mechanic certificate or graduates of Technical Intern Training (ii) in auto maintenance are exempt from the evaluation exam

  • Example: Because the passing score for the 30-question written exam is 65% or higher, 30 × 0.65 = 19.5 questions -> 20 or more correct answers are required to pass
WordMeaning
Specified Skilled Worker (i) Evaluation Exam (Qualification exam for Tokutei Ginou 1 status in the automotive maintenance field)
Written exam and practical exam (30 True/False written questions (60 min) and 9 two-choice practical questions (20 min))
Class 3 Automotive Mechanic (Japanese national mechanic qualification level on which this exam is based)

High-Frequency Exam Points and How to Remember Them

In inspection and disassembly/assembly, non-reusable parts (parts that must always be replaced with new ones once removed) = gaskets, packings, O-rings, oil seals, and cotter pins are tested almost every time. Always mark False on trick questions stating that O-rings or cotter pins may be reused if they show no visual defects.

For bolt and nut sequences, memorize this trio: Tightening cylinder head bolts = from center (inside) to outside; Loosening = from outside to inside (center); Wheel nuts = tapered face inward, tightened in a diagonal (star) sequence.

For brake air bleeding, releasing the brake pedal while the bleeder plug is still loose sucks air back into the line; therefore, exams frequently test the mandatory sequence: tighten the bleeder plug while holding the pedal depressed, and only then release the pedal.

In the Practical Exam (9 questions, 20 minutes), the three standard patterns are: (1) Names and scale readings of tools and measuring instruments, (2) Pass/fail judgment by comparing measurements with service limits, and (3) Selecting proper work procedures and safety rules. Pace your time carefully and solve calmly.

Key points


  • Gaskets, packings, O-rings, oil seals, and cotter pins are non-reusable parts and must always be replaced with new ones even if they look good

  • Cylinder head bolts: Tighten = inside to outside, Loosen = outside to inside / Wheel nuts: Tapered side inward, diagonal sequence

  • Brake air bleeding: Loosen the bleeder plug to expel fluid while holding the pedal down, and tighten the plug before releasing the pedal

  • Parts that get smaller with wear (pad thickness, etc.) are replaced when Measured < Limit; items that increase (bend, bore diameter, etc.) are replaced when Measured > Limit

  • SSW (i) Exam: Written is 30 True/False questions (60 min, 65% = 20 correct to pass); Practical is 9 two-choice questions (20 min, 60% to pass)
WordMeaning
Non-reusable (single-use only) (Must be replaced upon disassembly regardless of visual appearance)
Good / bad (pass / fail) judgment (Determining part serviceability by comparing measured values against limits)
Judgment test and planning test (The two components of the practical evaluation exam)

Inspection, Disassembly, Assembly, Adjustment & Repair

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