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Hino Truck FG17 and FG19 Workshop Manual download

Summary first (so you can jump to steps): this guide explains what main bearings are, why they fail, every part involved, the measuring and inspection work, and step‑by‑step removal/fitment and testing for main bearings on a Hino FG17/FG19 class truck engine. I do not give engine‑specific torque or clearance numbers — those must come from the Hino service manual or bearing supplier for your exact engine code — but I explain exactly what to measure, how to select bearings, how to install them, and all failure modes to watch.

Why this repair is done (theory, in plain terms)
- Function: main bearings support the crankshaft and let it spin smoothly inside the block. They create and maintain an oil film that carries the crankshaft load so metal never touches metal under normal running.
- Hydrodynamic lubrication analogy: imagine a speed skater (crankshaft journal) gliding on a thin, pressurized cushion of water (engine oil) created by the shape and motion. The bearing shells form the skate blade channels that squeeze and pressurize oil into a wedge to carry the load.
- If the bearings are worn, damaged, or clearance is wrong, the oil film collapses. That produces metal‑to‑metal contact, knocking, heat, low oil pressure, metal flakes in oil, and quickly leads to catastrophic failure (seizure, broken crank, destroyed block).
- Common reasons to replace mains: low oil pressure from bearing wear, audible knocking that changes with rpm/load, metal in oil filter or pan, scored journals, or during a rebuild.

All components you will encounter (what each one is and what it does)
- Crankshaft: the rotating shaft converting piston motion to rotational output. Journals (main journals where bearings ride, and rod journals) must be smooth and round.
- Main bearing shells (upper and lower halves): stamped steel backing with a babbitt or tri‑metal bearing layer; they fit into block saddles (upper) and main caps (lower). They have a locating tang and an oil hole/slot that must align with block oil holes.
- Main bearing caps: heavy cast pieces bolted to the block that clamp the lower bearing half around the crank. Caps are usually numbered and must be returned to their original position/orientation.
- Main cap bolts or studs: fasteners that clamp the caps. Many modern engines use torque‑to‑yield bolts that must be replaced every time; some use reusable studs/nuts.
- Dowel pins / alignment dowels: locate caps to block to maintain alignment.
- Thrust bearings (thrust washers): control crankshaft axial (end) play; usually located at one main (mid or rear main depending on engine).
- Rear main seal / front seal: seal oil at crank ends. Usually replaced when you disturb mains/rear cover.
- Oil galleries and oil pump: supply pressurized oil through holes in mains/rods to bearings.
- Bearing tangs / oil holes / oil grooves: ensure oil flow and shell retention.
- Assembly lube: heavy lube applied during assembly to protect bearings on first start.
- Plastigauge, micrometer, dial bore gauge, dial indicator: measuring tools to check clearances, journal diameter, block bore, and crank endplay/runout.
- Oil pump pickup, pan, oil filter: removed during disassembly; inspect and clean.

What can go wrong mechanically (and why)
- Wrong bearing clearance: too tight → insufficient oil film → seizure; too loose → low oil pressure, knock, fatigue failure.
- Installed shells backwards/out of position or oil holes misaligned → no oil supply to the bearing.
- Dirt/metal debris trapped when assembling → scoring and immediate failure.
- Reused torque‑to‑yield bolts or stretched bolts → cap movement, loss of clamp, bearing damage.
- Incorrect bearing size selection (normal vs undersize) — wrong clearances.
- Bent/cracked crank or damaged journals not recognized → repeated failures even with new bearings.
- Cap mislocation or cap bolt pattern changes → misalignment, uneven loading.
- Improperly installed thrust washers → incorrect endplay, gear misalignment, transmission issues.
- Poor cleaning, insufficient assembly lube, or damaged seals → risk of instant wear or leaks.
- Not checking crank runout or block alignment → early bearing failure.

Safety and prep (must do)
- Work on level surface, disconnect battery, support vehicle/engine safely. Use an engine hoist or stand if removing engine.
- Drain oil and coolant.
- Label and bag bolts/parts, take photos for reassembly.
- Clean workspace; bearings are extremely sensitive to contamination.
- Use gloves, eye protection, and proper lifting gear.

High‑level job options
- Option A: Replace bearing shells with crank in block (common when journals are within spec and only bearings are worn).
- Option B: Remove crankshaft and replace bearings and/or refinish crank (polish/grind) or fit undersize bearings (required if journals are scored beyond spec). This is more involved and preferred if journals are damaged.

Tools & consumables (practical list)
- Service manual (torque specs and clearances) — required.
- Engine hoist/stand (if pulling engine or crank).
- Socket set, breaker bar, extensions, impact gun (careful with torque).
- Torque wrench (capable of required torque).
- Micrometer (0.01 mm resolution) for journal diameter.
- Dial bore gauge or inside micrometer for main bore diameter.
- Plastigauge (quick clearance check), feeler gauges.
- Dial indicator with magnetic base (for crank endplay/runout).
- Shop press or arbor (if removing/installing crank).
- Engine assembly lube, clean solvent (degreaser), lint‑free rags.
- New main bearings (correct size), new thrust washers, new main bolts if required.
- New rear/main seals, gasket sets.
- Engine degreaser, compressed air (blow oil galleries clean).
- Torque angle gauge if bolts require angle tightening.
- Bearing puller/driver set if needed.

Step‑by‑step procedure (detailed)
I will give a combined flow covering both in‑block bearing replacement and full crank removal steps where appropriate.

1) Preparation
- Get the exact engine code from the engine tag — use the Hino manual and a bearing catalog to obtain journal sizes and torque specs.
- Drain oil and coolant. Remove oil pan, oil pickup, front timing cover (or timing gear cover), front pulley/harmonic balancer, possibly the timing gear/belt as needed to access the crank snout.
- Remove valve cover and timing components as required to rotate and lock the engine at TDC if needed.
- Remove connecting rod caps and/or pistons if removing crank. If doing in‑block mains only, you still often remove rod caps to make crank rotation easier.

2) Mark and document
- Number main caps and rod caps: stamp or mark #1, #2... and orientation. Caps are matched to their location and orientation; do not invert or swap.
- Photograph and label oil galleries, plug locations, and bolt configurations.

3) Remove main caps and inspect
- Loosen main cap bolts in a crisscross pattern, in stages — don’t suddenly remove all load on caps that may free up debris.
- Remove caps and lower bearing halves. Keep caps in order on a clean bench in the orientation they came off.
- Inspect bearing shells and journals for scoring, discoloration, and metal transfer. Note wear pattern: uniform or localized, presence of embedded debris, etching or pitting.

4) Measure journals and bores
- Clean journals and block thoroughly with solvent and rag; blow out galleries.
- Measure each main journal diameter at multiple points (two axial positions and 90° around) with a micrometer. Record.
- Use a dial bore gauge to measure the main bore internal diameter (or compare shell ID if you have reference). The bearing clearance spec is journal dia vs bearing ID — consult manual/bearing catalog to compute required bearing shell thickness.
- Measure crank journal roundness and taper; measure runout with a dial indicator on the crank (with crank installed or on a fixture). If runout or taper exceeds spec, the crank must be machined or replaced.
- Check main bores for out‑of‑round and alignment (line‑bore). Significant misalignment requires block machining.

5) Decide bearing size
- From journal measurements, choose standard or undersize bearings that give specified clearance. Bearing manufacturers provide shell thickness for standard and undersize bearings and recommended oil clearances. Do not guess — calculate.
- If journals are damaged beyond undersize machining limits, crank needs grinding or replacement.

6) Check thrust and endplay
- Inspect thrust faces and thrust washers. Measure crankshaft endplay with dial indicator: lock sprocket or flange, push crank forward/back and read movement. Replace thrust bearing/washer if worn; set new endplay to factory spec.

7) Clean everything
- Clean block saddles, cap faces, oil passages. Remove any burrs. Keep everything free of grit. Blow oil passages with compressed air while blocking open ends to avoid getting debris inside.

8) Fit new bearings (dry fit, then final)
- Check new shells into caps and saddles dry. Confirm tangs and locator fit. Ensure oil holes and slots align with the block oil holes.
- Check clearance with plastigauge as a first quick check:
- Install upper and lower shells, lightly coat bearing with a single strip of plastigauge along journal centerline, assemble cap and torque to spec in steps, rotate crank 360° by hand, then remove cap and measure width of crushed plastigauge compared to gauge chart to get clearance.
- Do not roll crank while plastigauge is installed beyond the recommended few degrees; follow plastigauge instructions.
- For precise check, calculate clearance from journal diameter and bearing ID or measure with dial bore gauge. Use multiple measurement points axially and circumferentially.

9) Replace or prepare bolts/dowels
- If bolts are torque‑to‑yield (TTY), replace them. Clean/replace dowels if worn/damaged.
- If using reusable studs, ensure they are clean and not stretched.

10) Final assembly of bearings (lubed)
- Apply assembly lube (not engine oil) to bearing surfaces.
- Insert upper shells in block, lower shells in caps. Align oil holes.
- Install caps in correct order and orientation. Tighten in stages following the factory torque sequence and values.
- If bolts require angle tightening, use specified angle and a new bolt if required.
- After final torque, rotate crank by hand; it should turn freely with a light drag from assembly lube but no tight spots or binding.

11) Re‑check clearances and endplay
- After torquing caps, check main clearance again (if you used plastigauge only before final torque, you must trust the final fit or measure again).
- Recheck crank endplay and ensure it's within spec. Adjust thrust washers if applicable.

12) Reinstall other components
- Reinstall oil pump pickup, oil pan (with new gasket and clean mating surfaces), timing cover/harmonic balancer, pistons/rods (if removed), front/rear seals (replace rear seal), and all accessories.
- Clean oil pan and check pickup screen for metal. If metal flakes present, clean thoroughly and consider replacing bearings/inspecting crank more thoroughly.

13) Pre‑start measures
- Prime the oil pump if possible (an auxiliary drill priming tool or filling oil galleries by hand) so bearings see oil before starting.
- Refill engine with correct oil and new oil filter.
- Turn the engine by hand many times to ensure free rotation; then crank (not start) to build oil pressure and check for leaks.
- On first start, watch oil pressure and listen for knocks. Idle at moderate RPM for warm‑up and then change oil after a short break‑in interval to remove any small metal debris.

Break‑in and testing
- Drive gently for the first 500–1,000 km (or as manual suggests). Monitor oil pressure, engine temperature, and listen for abnormal noise.
- Change oil and filter after break‑in sooner than normal to remove any bedding wear material.

Common inspection tips and failure signs during disassembly
- Coppery or shiny metal flakes in oil pan means bearing material in the sump — serious.
- Scored journals with deep grooves > machining allowance = crank grinding or replacement.
- Overheated (blueing) bearings indicate oil starvation/overheat.
- Bearing imprint patterns: full contact vs edge wear tells you whether alignment/cap torque or load distribution is wrong.

Troubleshooting and what to do if things are out of spec
- If journal taper/diameter out of spec: grind crank to undersize and select undersize bearings, or replace crank.
- If main bore is out of line: line‑bore the block or replace block (machine shop job).
- If crank endplay out of spec: replace or machine thrust washers, or fit new thrust bearings to correct endplay.
- If oil pressure stays low after correct clearances: inspect oil pump wear/clearances, relief valve, clogged pick up, or oil passages for blockage.

Analogy recap (quick)
- Bearings = the thin ice and skate blade: too thin oil film (thin ice) = skater scrapes the ice; too much gap = skater wobbles. Proper thickness and perfect smooth surface is essential.
- Main caps = the saddle that holds the axle on a wagon: if not seated or fastened correctly the axle moves and breaks the wagon.

Final cautions (short, critical)
- Never reuse TTY bolts. Always follow factory torque sequence and values.
- Always verify clearance with correct measuring tools; don’t guess.
- Keep parts and work area spotless — contamination kills bearings.
- If you are unsure about journal condition or block alignment, consult a machine shop. Bearing replacement without fixing a bad crank or block is temporary and can destroy a new set of bearings quickly.

This is a complete working overview and procedural guide. For the Hino FG17/FG19 you must use the model/engine‑specific service manual to get the exact torque values, bearing size chart, endplay and oil clearance specifications, and any model‑specific steps (e.g., special locking tools, cap numbering system, or service limits). Follow those numbers exactly during assembly.
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