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Hino 700 Series Workshop Manual download

Summary first: EGR (Exhaust Gas Recirculation) reduces combustion temperature and NOx by recirculating a metered amount of exhaust gas into the intake. On a Hino 700-series diesel this is usually an electronically controlled EGR valve assembly often paired with an EGR cooler, EGR pipe, sensors and actuators. Replacing the EGR valve requires basic mechanical skill, cleanliness, the right tools, caution around hot/coolant/exhaust, and following torque/manufacturer specs in the Hino workshop manual. Below is a beginner-friendly, detailed guide that explains what every component is, why the repair is needed, what can go wrong, and step‑by‑step replacement and tests. Follow safety notes. Do not skip the workshop manual for exact torque values, part numbers and wiring diagrams.

Why this repair is needed (theory, in plain terms)
- Purpose: EGR reduces NOx by returning a controlled amount of exhaust gas to the intake. Exhaust gas is mostly inert (CO2, H2O) and dilutes intake air, lowering peak combustion temperature so less NOx forms.
- Analogy: Think of the engine as a campfire. Adding some cooled exhaust gas is like dropping a wet log into the fire to lower the hottest flames. Too much or too little causes problems.
- Symptoms of a failing EGR valve:
- Check Engine Light / EGR-related diagnostic trouble codes (DTCs).
- Poor idle, stalling, loss of power or hesitation under load.
- Excessive smoke (black = too much fuel/poor air/EGR stuck open; white/grey can indicate coolant or other issues).
- Increased fuel consumption, rough running.
- Vacuum or electronic actuator not responding.
- Coolant leaks (if the EGR cooler is damaged).
- Why replacement vs cleaning: On Hino 700 trucks heavy carbon, a seized valve, failed position sensor or cracked valve housing usually means replacement. Cleaning can help if the valve moves but is gummed up; if electronics/position sensor fail, replace.

Main components (detailed descriptions)
- EGR valve (assembly): the mechanical gate that meters exhaust gas into the intake. Contains:
- Valve body and flange(s) — mounts to intake or EGR pipe.
- Pintle/plate or piston — the moving sealing element that opens/closes the passage.
- Actuator — can be vacuum, pneumatic, electric motor or stepper. Hino common setups are electronically-actuated (motor or solenoid) with a position sensor.
- Position sensor (potentiometer or Hall effect) — reports valve angle/position to the ECU.
- Mounting bolts and gasket — ensure a sealed flange joint.
- EGR cooler (if fitted): a heat exchanger using engine coolant to lower exhaust-gas temperature before it enters the intake. Components:
- Inlet/outlet coolant ports and hoses.
- Exhaust gas inlet/outlet and internal passages/tubes.
- Drain/collection features and mounting brackets.
- Gaskets and seals; corrosion-prone, can crack or clog with carbon.
- EGR pipe / crossover tube: the high-temperature exhaust pipe carrying gas from the exhaust manifold/turbo to the EGR valve/intake. Has flanged joints and gaskets.
- Exhaust manifold / EGR tap: source where EGR gas is drawn, usually a port on the exhaust manifold or near the turbo.
- Intake manifold / EGR inlet: where recirculated gases are introduced to the intake airflow.
- Electrical connectors & harness: power and feedback lines to EGR actuator and position sensor.
- Vacuum lines / solenoids (if vacuum operated): control vacuum to the actuator. Usually not on modern Hino 700s but may be on older variants.
- Sensors related:
- EGR position sensor.
- Differential pressure sensor (measures EGR flow across a restrictor or orifice) — some engines use this to confirm flow.
- Intake manifold pressure (MAP), boost sensors; EGR affects these readings.
- Engine coolant hoses and temp sensors (for EGR cooler).
- Gaskets, O‑rings, studs, bolts, heat shields.

What can go wrong (failure modes)
- Carbon build-up: restricts valve travel, clogs EGR passages, prevents sealing. Most common.
- Valve stuck open: excessive exhaust ingress -> rough idle, black smoke, loss of boost, potential soot/fouling of intake.
- Valve stuck closed: no EGR -> high NOx emissions and DTCs; engine may run hotter.
- Actuator or position sensor failure: ECU cannot control or monitor valve.
- EGR cooler leak/crack: coolant in intake (white smoke, possible hydrolock), coolant loss.
- EGR pipe leaks or broken studs: exhaust leak, loss of pressure, smoky, noisy.
- Electrical harness damage: broken wires/corroded connectors give wrong feedback or no control.
- Gasket failure: exhaust or coolant leaks.
- Turbo / intake contamination: soot can foul turbo vanes or intercooler.

Safety & prep (must read)
- Park on level, use wheel chocks, parking brake engaged.
- Let engine cool fully (EGR cooler and exhaust are very hot). Never open coolant when hot.
- Wear safety glasses, gloves, and protective clothing.
- Disconnect negative battery terminal to prevent electrical shorting when unplugging connectors.
- Have an appropriate coolant catch container and dispose of fluids legally.
- Use jack stands if lifting the cab or removing components under the truck. Support heavy components (EGR valve/cooler can be heavy).
- Keep dirt and debris out of intake and exhaust ports — cover openings with clean rags while parts are off.
- Follow local regulations for handling hazardous waste (coolant, soot).

Tools & consumables (typical)
- Basic hand tools: metric sockets (deep and shallow), ratchets, extensions, torque wrench, open-end wrenches, screwdriver set.
- Penetrating oil (PB Blaster).
- Gasket scraper and non-metallic scraper to avoid gouging faces.
- Wire brush and brass brush for carbon removal.
- Multimeter, scan tool / code reader (can command EGR and see position).
- Vacuum pump (if vacuum-actuated) or 12V bench supply / actuator test tool (for electric actuators).
- New EGR valve (OEM part), new gaskets, new bolts/studs if necessary, new EGR cooler if needed.
- Coolant, drain pan, hose clamps, zip ties, rags.
- Anti-seize (sparingly on studs if recommended), gasket sealant only if manufacturer permits.
- Torque wrench, mirror and flashlight.

Step-by-step replacement (generalized for Hino 700 series)
Important: use the Hino Workshop Manual for exact steps and torque values. The steps below are comprehensive for a beginner mechanic but must be adapted to the specific engine model (J08 or other).

1) Preparation
- Park, chock wheels, set parking brake. Let engine cool 60–90+ minutes.
- Disconnect negative battery terminal.
- Drain coolant to below the level of the EGR cooler connections (open radiator drain or lower hose into a catch pan). Do not fully drain unless needed; capture coolant for reuse if clean.
- Remove any panels or covers for access. Remove air inlet piping between air cleaner and turbo/inlet manifold that blocks access to the EGR assembly. Label hoses and connectors as you go.

2) Access and inspection
- Identify EGR valve, EGR cooler, EGR pipe, and related hoses. Take reference photos of connector and hose routing for reassembly.
- Spray penetrating oil on studs/nuts and allow to soak (especially exhaust-side bolts).
- Unplug electrical connectors to the EGR valve actuator and position sensor, and any EGR temp or EGR-related sensors.
- If there are vacuum lines, mark and remove them.

3) Remove EGR pipe (exhaust side)
- Loosen and remove bolts/studs securing the EGR pipe to the exhaust manifold / turbo outlet and to the EGR valve/cooler. Support the weight of the pipe. If studs are corroded, remove carefully; heat and penetrating oil may help.
- Remove the EGR pipe and plug both ends with shop rags to prevent debris entry.

4) Remove EGR cooler (if fitted)
- Disconnect coolant hoses feeding the EGR cooler. Have a catch pan under; plug hoses and ports quickly to avoid contamination.
- Remove mounting bolts and any brackets. Carefully lower the cooler — it can be heavy and awkward. Keep the mating surfaces covered.
- Inspect cooler: look for signs of coolant leakage, internal clogging (heavy carbon), and corrosion. If cracked or leaking, replace.

5) Remove EGR valve
- Remove bolts securing EGR valve to the intake/EGR pipe. Pull the valve straight out. Protect intake port with clean shop rag immediately.
- Inspect the valve pintle/seat for carbon deposit and the actuator for free movement. Check the position sensor connector pins.

6) Clean and inspect mating surfaces & passages
- Carefully scrape gasket material from flanges with a non-marring scraper. Do not let debris fall into intake or exhaust; vacuum or use shop rags to block ports.
- Inspect intake/exhaust ports and EGR pipe for carbon; remove loose deposits with a brass brush. Avoid aggressive grinding that can damage ports.
- Inspect turbo/intercooler and intake for excessive soot; clean as required.

7) Bench test EGR valve (recommended)
- Using a scan tool: command EGR open/close and observe position feedback.
- With a multimeter: check sensor reference/power/ground connectors per workshop manual.
- For vacuum actuators: apply vacuum with handheld pump and watch movement.
- If valve fails tests, replacement is justified.

8) Install new EGR valve (and new gaskets)
- Fit new gaskets (use OEM gaskets). Ensure mating faces are clean and dry.
- Position the EGR valve, insert bolts and finger-tighten. Torque to OEM spec in a criss-cross pattern. (Do not over-torque; if you lack the exact spec, consult the manual — typical practice on intake/exhaust flange bolts is to tighten to run-in then apply specified torque.)
- Reconnect position sensor and actuator connectors.

9) Reinstall EGR cooler & EGR pipe
- Install new gaskets at flanges and hand-start bolts. Tighten bolts progressively and torqueto the manufacturer's specs.
- Reconnect coolant hoses and clamps securely. Replace any hoses that are cracked or brittle.
- Reinstall EGR pipe between exhaust manifold and EGR valve/cooler. Use new gaskets and tighten in a cross pattern.

10) Reconnect wiring, hoses, and air/system components
- Reconnect any vacuum lines, sensors and wiring harness clips.
- Reinstall intake piping, intercooler/turbo piping, heat shields and covers.
- Ensure all clamps and connections are tight and that hoses are routed without kinks.

11) Refill and bleed coolant
- Refill cooling system with clean coolant to the proper mix and level.
- Follow Hino bleed procedure to remove air from coolant circuit (some systems require running engine to thermostat open and continuing to top up). Check EGR cooler and hose connections for leaks.

12) Reconnect battery and scan/clear codes
- Reconnect negative battery terminal.
- Use scan tool to clear stored EGR-related codes. Use the tool to command the EGR valve and monitor position to confirm operation.

13) Start-up and verification
- Start the engine and watch for coolant leaks and exhaust leaks. Idle for a few minutes; monitor temperature.
- Using a scan tool, verify EGR position feedback, EGR duty command, intake/exhaust pressures and look for DTCs.
- Observe for rough idle, smoke, or unusual noises. If the valve is commanded open and closed, you should see expected changes in MAP/DP.
- Road test under light and moderate load. Monitor for codes and performance.

14) Final checks
- After a short run, recheck coolant level and torque of accessible bolts.
- Confirm no leaks, confirm EGR operation with scan tool, ensure no limp-mode conditions.

Testing & troubleshooting after replacement
- If codes persist: scan for new DTCs (wiring, position sensor or differential pressure sensor faults).
- If EGR not moving: check power/ground to actuator, check connector continuity, test actuator directly per manual.
- If white smoke / coolant smell: suspect EGR cooler leak — stop engine and inspect immediately to avoid hydrolock damage.
- If black smoke and roughness: verify EGR is not stuck open; check boost pressure and MAF/MAP readings.
- Use a differential pressure sensor (if present) to confirm flow; compare readings to expected values in the manual.

Cleaning vs replacing
- Small carbon deposits can be cleaned with brush and approved cleaners; heavy carbon often requires replacement. Cleaning ports without removing valve sensors is tricky; if valve movement is impeded repeatedly, replacement is best.

Common beginner mistakes to avoid
- Not blocking intake/exhaust ports when parts removed — leads to debris entering engine.
- Not replacing gaskets — causes leaks.
- Over-tightening flange bolts — damages flange or threads.
- Not bleeding coolant properly — causes overheating/air lock in system.
- Failing to clear DTCs or to run diagnostic checks — leads to repeat failure or limp mode.
- Using aggressive chemicals that damage sensors.

Quick diagnostic checks before replacing
- Use a scan tool to check voltage/position feedback and DTCs.
- Check for vacuum (if applicable) or apply a commanded input to see if valve moves.
- Look for differential pressure sensor readings inconsistent with commanded EGR duty.
- Inspect turbo and intake for heavy soot; if turbo is clogged, EGR replacement alone may not fix symptoms.

Final notes
- Always use OEM or OEM-quality replacement parts and gaskets.
- Keep a clean workspace and take photos while disassembling to help reassembly.
- Respect hot liquids, exhaust components, and electrical connectors.
- If you’re unsure about torque values or wiring, use the Hino 700 Workshop Manual or Hino dealer tech support for the specific engine model and year.

This guide gives the full picture and stepwise actions a beginner mechanic needs to replace an EGR valve assembly on a Hino 700-series truck. Follow the Hino workshop manual for exact torque figures, tightening sequences and model-specific steps.
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