Note: 1HZ, 1PZ and 1HD‑T are Toyota diesel engines — they use glow plugs, not spark plugs. Below are technician-level, step‑by‑step instructions for removing, testing and replacing glow plugs on these engines.

Tools & supplies
- New glow plugs (OEM or exact spec replacements) — replace all cylinders if possible. Also get new sealing washers/O‑rings if used.
- Metric hand tools: ratchet (3/8" drive), short and long extensions, universal joint.
- Deep glow‑plug socket sized to fit the glow plug hex (use the correct size; DO NOT use an open wrench). If unsure, measure the plug hex or check parts catalog.
- Torque wrench capable of low torque (0–25 N·m).
- Small combination wrenches (for terminal nuts/lead nuts).
- Multimeter (for resistance/voltage checks).
- Penetrating oil (e.g., PB Blaster), small brush, clean rags.
- Compressed air or blower to clean around plugs.
- Dielectric grease (for electrical contacts).
- Anti‑seize only if manufacturer permits (many OEMs advise against when plugs are coated).
- Safety glasses, gloves.
- Left‑hand extractor set and thread repair kit / helicoil or time‑sert (only if a plug snaps).

Safety precautions
- Work on a cold engine. Hot diesel heads and plugs are easy to break.
- Disconnect the negative battery terminal before beginning.
- Work in a well‑ventilated area; diesel fuel/solvents can be harmful.
- Keep metal tools clear of the battery and glow plug control module connectors to avoid shorts.
- Do not use an impact wrench on glow plugs — they shear easily.
- If a plug is seized, use penetrating oil and patience; heat near fuel/lines is dangerous.

Step‑by‑step procedure
1. Prepare
- Park on level ground, set handbrake, let engine cool completely.
- Disconnect negative battery terminal.
- Remove engine covers, air intake snorkel, intercooler/ducting or any components blocking access to the cylinder head top. Label hoses/connectors if you remove them.

2. Locate glow plugs
- On these Toyota diesels the glow plugs live in the cylinder head (top). Identify electrical leads and terminal nuts for each plug.

3. Clean area
- Blow out any dirt/debris around each glow plug with compressed air. Prevent any debris from falling into the combustion chamber.

4. Disconnect electricals
- Remove the terminal nut or unplug the electrical connector from each glow plug. Keep track of small nuts/washers.

5. Soak with penetrating oil
- Spray penetrating oil around the base of each glow plug thread. Let soak 30–60 minutes (longer if heavily corroded).

6. Loosen and remove plugs
- Fit the correct deep glow‑plug socket onto the plug, use an extension and a universal joint if needed to get a straight pull. Ensure socket seats fully and squarely to avoid rounding the hex.
- Turn slowly and steadily counter‑clockwise. If it resists, apply more penetrating oil and let sit. Do small back‑and‑forth motions to break the seal.
- Once loose, remove by hand or with socket. Keep plugs straight as they come out to avoid damaging threads.

7. Inspect old plugs
- Check for carbon build‑up, cracking, or melting. Record resistance with a multimeter (between tip and terminal). Typical glow plug resistance is very low (often <5 Ω); consult parts specs. Mark any that are open circuit or high resistance.

8. Prepare new plugs
- Fit new sealing washers/O‑rings (use supplied hardware). If manufacturer allows anti‑seize, apply a very light smear to threads — otherwise leave as OEM coated and install dry.
- Thread glow plugs in by hand to avoid cross‑threading.

9. Torque to spec
- Tighten new glow plugs with a torque wrench to the correct torque — typical range is about 8–14 N·m (7–10 lb·ft). Consult the specific service manual for each engine model and use that value. Do not over‑torque.

10. Reconnect electricals
- Reattach the terminal nut or connector. Apply a tiny amount of dielectric grease to the contact to reduce corrosion and ensure a good connection.

11. Reassemble and test
- Refit any removed intake/intercooler/plastic covers.
- Reconnect negative battery terminal.
- Turn ignition on and verify glow plug indicator (if present) and that glow plug relay clicks. Start engine — should start more easily.
- Optionally, measure voltage at each glow plug connector with ignition on to confirm supply (should be battery voltage when activated).

Testing glow plugs (bench and in‑car)
- Bench: measure resistance between terminal and body — typical low ohm value; an open circuit is bad.
- In‑car: with the glow control activated, check for battery voltage at each terminal. If resistance is very high or there’s no voltage, check wiring, relay and fuse.

Common pitfalls & how to avoid them
- Using the wrong socket or impact tools: leads to rounded hexes or snapped plugs. Use the correct deep socket and hand tools only.
- Not cleaning before removal: dirt falls into cylinder — blow out area first.
- Removing electrical connection last or pulling on wires: always disconnect the terminals before trying to loosen plugs.
- Cross‑threading or over‑torquing new plugs: always start by hand and use a torque wrench with the correct low torque.
- Breaking a glow plug in the head: if seized, soak longer, use careful gradual force, and do not use an impact. If it breaks, extraction and thread repair (helicoil/time‑sert or re‑tap) are required — head repair can be expensive.
- Neglecting washers/seals: fuel/oil leaks or poor sealing. Replace sealing washers/O‑rings with new ones.
- Mixing old and new glow plugs: different heatups cause uneven starting — replace the whole set if possible.

If a plug snaps or threads are damaged
- Stop. Remove surrounding components to access area.
- Use left‑hand extractors carefully, or drill and install a helicoil/time‑sert repair for the thread (recommended by machine shop).
- If the head is damaged, consult a machine shop — do not drive the bolts/attempt aggressive extraction without experience.

Replacement parts required
- Glow plugs (correct part number for your engine model).
- Sealing washers or O‑rings (as required).
- Optional: replacement terminal nuts/connectors if corroded.
- If plug(s) fail: thread repair kit (helicoil/time‑sert) or head repair service.

Final notes
- Always consult the specific factory service manual for exact torque specs, plug part numbers and any engine‑specific access steps (e.g., 1HD‑T may require removal of some intercooler piping or intake components for access).
- Replace all glow plugs as a set for even performance and starting.

End.
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2011 Toyota Land Cruiser 76 LX 0-80 km/h 1HZ acceleration Short acceleration video on my cruiser 1HZ Altitude 1440m Non turbo Snorkel.

1990 Toyota Land Cruiser Turbo Diesel Right Hand Drive HDJ81 1HDT driving RPM 1990 Toyota Land Cruiser Turbo Diesel Right Hand Drive HDJ81 1HDT driving RPM.

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