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Hino FD FE FF SG FA FB Series Workshop Manual download

1) Safety & prep
- Action: Isolate batteries (both if 24V), tag/photograph wiring, wear PPE, note starter model/part numbers. Confirm system voltage.
- Theory: Prevents short circuits and protects you and the vehicle electrical system.
- How this fixes faults: Avoids introducing new electrical damage or safety incidents that can mask/complicate diagnosis.

2) On‑vehicle symptom verification and basic electrical checks
- Action: With a helper, record cranking voltage at battery and starter, measure voltage drop (battery negative to starter negative, battery positive to starter stud) and measure cranking current (clamp or shunt + ammeter).
- Theory: Voltage under load and current draw reveal whether the problem is electrical (poor connections, weak battery) or mechanical (high torque load from engine or starter internals). High current + low voltage = internal short/drag or heavy mechanical load; low current + clicking = solenoid/field/open circuit.
- How this fixes faults: Pinpoints whether to remove starter or fix wiring/battery first; prevents unnecessary bench teardown.

3) Characterize symptom to failure mode
- Action: Map symptom to probable causes: no crank (open solenoid/armature/bad brushes), slow crank (low battery, high starter internal resistance, worn brushes, bad commutator, dragging bearings), freewheel/grind (Bendix/drive failure or flywheel ring gear damage), intermittent (brush spring fatigue/dirty commutator/loose connections).
- Theory: Starter is an electromechanical device: solenoid engages drive and closes heavy contacts; armature + field create torque; brushes transfer current; bearings support rotation; Bendix transmits torque. Each symptom ties to these subsystems.
- How this fixes faults: Focuses inspection and tests to the most likely components.

4) Remove starter
- Action: Disconnect wiring, remove mounting bolts, note alignment/shims, remove starter. Keep fasteners and any shims in order.
- Theory: Mechanical removal needed for bench testing and controlled inspection.
- How this fixes faults: Enables accurate bench diagnosis and repair.

5) Bench functional test before disassembly
- Action: On bench, apply correct system voltage to solenoid and main stud briefly; observe drive engagement, armature rotation, unusual noises, excessive draw. If available, use starter test bench to measure torque and current.
- Theory: Confirms field/armature/solenoid behavior under known conditions to compare with post‑repair results.
- How this fixes faults: Establishes baseline, shows which subsystem fails under load so you don’t rebuild unnecessarily.

6) Remove external components and solenoid
- Action: Remove solenoid from housing, detach end caps, brushes/brush holder assembly, drive/Bendix if serviceable.
- Theory: Accesses internal components for inspection and testing.
- How this fixes faults: Allows isolation and replacement of faulty subsystems.

7) Inspect drive (Bendix) and pinion
- Action: Check teeth wear, freewheel mechanism, pawls/splines, circumferential play, grease condition. Clean and check for binding.
- Theory: Bendix freewheels during engine run-on; worn teeth or sticky ratchet prevents proper engagement or causes grinding.
- How this fixes faults: Replacing/cleaning Bendix restores reliable engagement and eliminates grinding or failure to engage.

8) Inspect commutator and armature
- Action: Visually inspect commutator for grooving, burning, pitting, undercut mica, evidence of arcing. Measure mica ridge height, commutator diameter, runout. Perform growler test or megger for armature shorts/insulation failure; measure inter‑coil and segment resistances.
- Theory: Commutator + brushes transfer current to armature windings; uneven surface or shorts reduce effective current transfer and produce arcing, heating, low torque. Growler detects shorted coils (rotor shorted turns).
- How this fixes faults: Resurfacing, undercutting and replacing defective armature or coils restores even current distribution and torque, curing slow/no crank and overheating.

9) Inspect brushes and springs
- Action: Measure brush length, check for proper seating, inspect for burnt surfaces, check spring force (compare to spec), inspect brush holder for movement and insulation.
- Theory: Brushes wear and springs weaken; insufficient contact area or spring force increases contact resistance causing voltage drop and heating, reducing torque.
- How this fixes faults: New brushes or springs reduce resistance and restore proper current transfer and starting torque.

10) Inspect field coils/stator and pole pieces
- Action: Check field coil insulation, measure coil resistance vs spec, inspect for burned or compressed coils, check pole shoe alignment and secure bolting.
- Theory: Field coils create stationary magnetic flux; shorted/weak coils reduce magnetic field strength, lowering torque.
- How this fixes faults: Repair or replace damaged coils to restore field strength and torque.

11) Inspect bearings/bushings and shaft
- Action: Check radial play, axial endplay, bearings for roughness, bushings for wear, inspect shaft scoring. Measure against allowable tolerances.
- Theory: Worn bearings/bushings increase friction and misalignment, causing drag, high current, and eccentric commutator wear.
- How this fixes faults: Replacing bearings/bushings and correcting shaft runout removes mechanical drag and prevents commutator/brush damage, reducing current draw and noise.

12) Inspect solenoid internals and heavy contact
- Action: Disassemble solenoid, inspect plunger, return spring, and especially the heavy main contacts for pitting, welding or high resistance. Measure coil resistance and continuity.
- Theory: Solenoid both mechanically pushes the drive and closes the heavy current path. High resistance/spattered contacts cause voltage drop and intermittent operation; weak plunger spring or worn sleeve prevents full engagement.
- How this fixes faults: Cleaning, machining or replacing contacts and restoring plunger movement ensures full battery voltage reaches the starter and that drive engages reliably.

13) Cleaning and repair decisions
- Action: Clean commutator with solvent, remove carbon dust, clean pole shoe surfaces. Decide which parts to resurface (commutator turn), replace (brushes, bearings, solenoid contacts, Bendix), or rewind/replace stator/armature.
- Theory: Contaminants and damaged surfaces produce resistance and arcing; some damage is serviceable (machining commutator) but shorts or burnt windings require replacement.
- How this fixes faults: Restores low resistance current paths and good magnetic geometry.

14) Commutator turning and mica undercut
- Action: If within spec, turn commutator on lathe to true it, remove pits/ridges, then undercut mica between bars to correct seating. Finish-lap brushes to conform.
- Theory: True, smooth, and properly profiled commutator reduces brush arcing, ensures uniform contact and current distribution across coils.
- How this fixes faults: Reduces arcing and brush wear, increases effective contact area and torque, cures intermittent/noisy/overheating issues.

15) Replace brushes, springs, bearings, bushings, contacts as needed
- Action: Fit new brushes with correct orientation and seating, install correct spring tension, press in new bearings/bushings, replace solenoid contact assembly if worn.
- Theory: Fresh contact materials and low-friction bearings restore electrical and mechanical integrity.
- How this fixes faults: Lowers internal resistance, restores field strength transfer and mechanical rotation—resulting in normal cranking speed and reliability.

16) Reassemble with correct shims and endplay
- Action: Reassemble ensuring correct armature endplay, align pole shoes, torque fasteners to spec, fit any drive retaining clips. Apply the correct type and amount of high‑temp grease only where specified (drive bearings, not commutator).
- Theory: Correct endplay prevents axial rubbing/drag; correct grease prevents binding and premature wear.
- How this fixes faults: Eliminates binding or misalignment that caused high current and mechanical noise.

17) Bench post‑repair functional test
- Action: Repeat bench test: check drive engagement, measure no‑load speed, measure torque/current under simulated load if possible, verify solenoid contact voltage drop is low.
- Theory: Confirms repairs restored electrical continuity, magnetic field, and mechanical freedom.
- How this fixes faults: Validates the repair eliminated original failure modes before reinstalling.

18) Reinstall and final vehicle electrical checks
- Action: Reinstall starter using original shims/alignment, torque bolts, connect cables with clean terminals. Repeat voltage drop tests during cranking and measure cranking current/engine rpm.
- Theory: On‑vehicle tests ensure starter takes current and produces torque under real load; voltage drop confirms cable/terminal integrity.
- How this fixes faults: Confirms both starter and vehicle wiring are sound; if voltage drop persists, addresses wiring rather than starter.

19) Symptom verification and run‑in
- Action: Start engine several times, listen for engagement/grinding, inspect for heat or smoke. Check starter mounting and electrical connections after a short run.
- Theory: Early operation will reveal residual issues like intermittent engagement or overheating.
- How this fixes faults: Ensures durability of repair and that no secondary faults exist.

20) Common fault-to-repair mapping (quick reference)
- Slow cranking, high current: worn brushes, high- resistance solenoid contacts, shorted armature coils, dragging bearings — repair: replace brushes/springs, resurface or replace commutator/armature, replace bearings, clean/replace solenoid contacts.
- No crank, single click: solenoid coil open, bad solenoid contacts, or open armature/field — repair: test/replace solenoid contacts or coil, repair wiring.
- Freewheeling/no engagement: Bendix drive or pinion engagement parts worn or sprung — repair: replace Bendix/pinion assembly, check flywheel ring gear.
- Intermittent start: weak brush springs, dirty commutator, loose wiring — repair: replace springs/brushes, clean commutator, tighten connections.
- Grinding during engagement: damaged Bendix or flywheel gear teeth or misaligned drive — repair: replace Bendix and/or resurface or replace flywheel ring gear, check starter alignment.

21) Notes on parts & tolerances
- Action: Use OEM or approved reman parts for heavy‑duty starters; check Hino workshop specs for resistance, brush length, spring force, commutator dimensions and torque values.
- Theory: Starters are designed to tight tolerances; mixing improper parts degrades life/performance.
- How this fixes faults: Correct parts prevent premature recurrence.

End — follow Hino workshop manual specs for exact resistances, torques and part numbers.
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