Tools & consumables
- Hand tools: metric socket set (6–19 mm), 1/4" and 3/8" ratchets, extensions, universal joint/swivel.
- Torx/hex set (if used on your model).
- Torque wrench (0–150 Nm range; low-range accuracy down to ~5–10 Nm).
- Transmission jack or floor jack + wood block (to support transmission).
- Drain pan (large), funnel.
- Clean lint‑free rags, solvent/brake cleaner, parts tray/magnetic tray.
- Gasket scraper, plastic/or brass pick set (for seals and check balls).
- Snap‑ring pliers (if needed by your transmission).
- Seal driver or appropriate sized socket (if fitting seals).
- New transmission filter & pan gasket, valve body gasket(s)/O‑rings, new valve body assembly (or rebuild kit), replacement bolts if specified, new pan bolts (if single‑use), new ATF (OEM spec).
- Gloves, eye protection, wheel chocks, jack stands, shop manual or OEM torque/spec sheet.

Safety first (non‑negotiable)
- Work on level surface. Chock wheels. Block the vehicle so it cannot roll.
- Disconnect negative battery terminal to avoid shorts when disconnecting solenoids.
- Support vehicle securely on jack stands. Never rely on a jack alone.
- Use a transmission jack or stable support under the transmission — the transmission will be supported while valve body removed.
- Wear gloves and eye protection. Keep solvent/ATF away from hot surfaces and ignition sources.
- Keep small parts separate and clean; contamination kills transmissions.

Preliminary checks / preparation
1. Verify exact transmission model and get the factory service manual for torque specs, bolt lengths, valve body disassembly drawings, check‑ball and spring locations, and ATF type and capacity. Valve body layouts differ by transmission—do not proceed without the correct diagram.
2. Acquire a new valve body or a correct rebuild kit (with new gaskets, check balls if included, springs, seals, filter). Replace filter and pan gasket as a minimum.
3. Warm the transmission slightly (drive briefly) to reduce viscosity, then park, apply parking brake, and block wheels. Warm fluid drains faster and is cleaner.

Step‑by‑step procedure
1. Drain transmission fluid
- Raise vehicle, support on jack stands.
- Place drain pan under transmission pan.
- Remove pan bolts slowly to let fluid run out; drop pan. Save bolts/magnets location. Inspect magnets for metal debris.
- Remove old pan gasket and clean pan and mating surfaces with solvent. Put parts in a clean area.

2. Remove transmission pan and filter
- Remove transmission filter: it may be held by screws or press fit. Note orientation.
- Inspect for heavy debris/metal. Photograph magnet patterns and pad locations for reference.

3. Support transmission & prepare to remove valve body
- Support transmission with a transmission jack or floor jack under case with wood block to distribute load. You’re not removing the transmission — just supporting it while the valve body is removed.
- Disconnect all electrical connectors on the valve body/solenoids carefully—release tabs, do not pull on wires. Label connectors if needed.
- Remove any linkages, speedometer drives, or brackets blocking access.

4. Remove valve body bolts and lower valve body
- Loosen valve body bolts in a cross pattern to relieve stress; remove them gradually rather than removing one completely first (prevents warping).
- Be aware: different bolt lengths exist. Keep bolts organized in a tray in the pattern you remove them (or photograph).
- Lower valve body carefully — it is heavy and contains springs/check balls. Keep it level.
- If valve body is attached to an intermediate plate, remove both, keeping track of thin separator plates, shims, or check balls. Some transmissions have small captive balls/springs between body and separator plate — note their exact positions.

5. Inspect and clean
- Inspect mating surfaces, separator plate, and bores for scoring, wear, or broken components.
- Clean surrounding area with lint‑free cloth and solvent; do not let debris fall into transmission.
- Clean valve body exterior and new parts if reusing. Do not disassemble valve body unless you are using the correct manual and parts kit; internal spools are delicate and require clean environment.

6. Replace filter, gaskets, seals and install new valve body
- Fit new filter and pan gasket.
- If replacing valve body: compare new to old, ensure all ports and bolts align, transfer any necessary brackets or sensors.
- Replace any rubber O‑rings, seals, and check balls as per kit manual; install any new spring/ball kits exactly to spec.
- Install valve body making sure separator plate and springs/check balls are correctly seated. Pay strict attention to orientation and placement of check balls (common failure point).
- Hand‑start bolts in their original positions. Torque in the manufacturer’s sequence and to the specified torque. (Typical valve body bolt torques are low — often in the 7–15 Nm range — but verify factory values. Tighten in stages and follow the sequence.)

7. Reconnect solenoids and wiring, reinstall pan
- Reconnect all electrical connectors and any brackets or linkages.
- Install pan with new gasket and torque pan bolts to spec in a crisscross pattern.
- Reinstall any removed crossmember or heat shields.

8. Refill ATF
- Lower vehicle enough to access fill/dipstick but keep safe on stands.
- Refill with the correct ATF type (consult shop manual — many Toyota automatics require Toyota Type T-IV or Dexron III/VI equivalents; older units may use Dexron II). Use a funnel and pump if needed.
- Start with the recommended initial quantity (consult manual) — if unknown, add enough for the transmission to be slightly below full cold level, then adjust after running.

9. Bleed and check operation
- Reconnect battery.
- With parking brake on and engine idling, cycle the shifter through all gears, pausing a few seconds in each to circulate fluid and seating clutch packs.
- Check for leaks around pan and connectors.
- With engine warm and on a level surface, check fluid level per OEM procedure (usually with engine idling in Park or Neutral, shift into each gear and back to Park, then check dipstick hot). Top up to proper level.

10. Road test & final check
- Test drive: full range of shifts, under load. Monitor for harsh shifts, slipping, or leaks.
- After cool down, re‑check torque of pan and valve body bolts after a few hundred miles if manufacturer recommends.

How specific tools are used
- Torque wrench: tighten valve body bolts in stages and in the specified sequence to prevent distortion. Use the correct low‑range setting for small bolts and recheck.
- Transmission jack/floor jack + wood block: supports the transmission housing to remove load on valve body fasteners and prevents movement while working.
- Plastic/brass picks: remove O‑rings and seals without nicking bore surfaces.
- Gasket scraper: remove old gasket material (use plastic or brass end if aluminum mating surfaces).
- Solvent & lint‑free rags: clean mating surfaces and ensure no debris enters fluid paths.
- Parts tray/magnetic tray: keep bolts and small parts in order; label for original location.

Common pitfalls — avoid these
- Reusing old gaskets/filters: leads to leaks and contamination. Always replace filter and pan gasket; replace valve body gasket and O‑rings.
- Losing or misplacing check balls/springs: many transmissions have very small check balls under the valve body; incorrect placement causes major hydraulic faults. Refer to manual diagram and keep parts ordered.
- Mixing up bolt lengths: installing a long bolt where a short bolt should be can damage valve body or internal passages.
- Over‑torquing bolts: warps valve body or crushes gaskets. Use factory torque sequence and values.
- Contamination: do not allow dirt or lint into valve body or transmission. Work in as clean an environment as possible.
- Wrong ATF: using incorrect fluid can cause shift problems and shorten life. Confirm correct specification.
- Not supporting transmission: removing bolts without support can bend housings or shift gearsets.
- Electrical connector damage: pull on plastic tab, not the wires.
- Not verifying bolt torque/sequence: causes leaks, warping, and erratic shifts.

Replacement parts (typical)
- Complete valve body assembly OR valve body rebuild kit (spools, springs, seals, check balls if available).
- Transmission filter and pan gasket.
- Pan bolts (if specified as single‑use) and valve body bolts (inspect for stretch; replace if damaged).
- O‑rings, separator plate gaskets.
- ATF — correct OEM type and quantity.

Final note
Follow the factory service manual for your exact transmission model for bolt torque values, bolt-length locations, check‑ball locations, and ATF type/capacity. Small errors (bolt placement, check‑ball position, contamination) are the leading causes of failure after valve body work — work methodically, keep parts organized, and don’t rush.
rteeqp73

Land Cruiser 12HT testi Testing rebuilt Toyota Land Cruiser HJ61 12H-T engine.

This Week at Mr Landcruiser #11 - LS3 Extra Cab Ute, 12HT swaps and new wrecks! Join Paul for a quick spin around the Mr Landcruiser yard as he guides you through whats happening this week at Mr Landcruiser!

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Short answer up front: Toyota 2H and 12H‑T are diesel engines — they do NOT have an ignition coil. If you're troubleshooting what people often call “ignition” on these engines, you want the glow plugs / glow relay (preheat system) or the injection pump electrics. Below is a step‑by‑step procedure to replace glow plugs (and how to check/replace the glow relay), with tools, safety steps, how each tool is used, and common pitfalls.

What you need (tools & parts)
- Tools:
- Socket set (6–19 mm), deep sockets including the correct size deep socket for glow plugs (commonly 8–10 mm hex or 10–12 mm hex style depending on glow plug)
- 1/4" and 3/8" ratchets, extensions (3–6 in.), universal joint
- Torque wrench (0–100 Nm) — for final torque of glow plugs and connectors
- Multimeter (DC volts/ohms)
- Penetrating oil (PB Blaster or equivalent)
- Small wire brush, contact cleaner
- Heat source (propane torch or heat gun) — only if glow plugs are seized (use with caution)
- Insulated pliers, pick set
- Antiseize compound or copper paste (small amount)
- Replacement glow plugs (OEM or equivalent), new copper crush washers/seals if used
- Replacement glow plug relay/module if faulty
- Small funnel, rags, safety glasses, nitrile gloves
- If a glow plug breaks: extractor/EZ‑out set, helicoil kit (for thread repair)
- Parts:
- Correct model glow plugs for 2H / 12H‑T (one per cylinder) — buy OEM or reputable aftermarket
- Glow relay/module (if diagnostics show failure)
- New seals/washers and possibly new wiring boots or connector ends
- Antiseize compound (small tube)

Safety precautions
- Disconnect negative battery terminal before starting to avoid shorts and accidental cranking.
- Work with engine cold unless using heat intentionally to free seized plugs; wear gloves and eye protection.
- If heating the head to free a plug, keep flame away from fuel lines, hoses, wiring — remove close combustible items.
- Use a current‑limiting method when bench‑testing glow plugs (fuse or multimeter) to avoid short/high current hazards.
- If a glow plug snaps off in the head, stop and assess: thread repair often required — avoid further damage by over‑torquing.

Step‑by‑step: Remove & replace glow plugs
1) Preparation
- Park vehicle on level, engine cold, parking brake on.
- Disconnect negative battery terminal.
- Remove any obstructing components to access glow plugs: intake snorkel, air cleaner, rocker cover or manifold pieces as needed. Use hand tools and label connectors.

2) Identify glow plugs
- Glow plugs are threaded into the cylinder head; each has a single electrical lead (boot) or connector.
- Clean area around each plug with brush and cloth to avoid debris falling into ports.

3) Test (optional but recommended)
- Before removal test each glow plug with a multimeter: measure resistance between terminal and body — typical diesel glow plugs are low resistance (often 0.2–5 ohms). Open circuit or very high resistance = bad. Alternatively, measure 12V at plug while activating preheat (with battery connected and key to preheat position) — use caution.
- Test relay: check for 12V at relay feed and output when preheat switched on. If none, relay may be bad.

4) Loosen & remove glow plug
- Spray penetrating oil around each plug base, allow 10–15 minutes.
- Use the correct deep socket on the glow plug terminal: put socket straight and square to avoid rounding the hex/hexagon.
- Use short extension and ratchet; break torque carefully. Glow plugs seize easily — apply steady gradual force.
- If a plug won’t budge, apply penetrating oil again and gently heat area around plug (NOT the plug itself) for a minute, then try again. Do NOT apply excessive impact force — avoid snapping the plug.
- Remove plug by hand once free. Keep wiring boots/terminals intact.

5) Prepare new plug & install
- Compare new plug to old for length/threads.
- Lightly coat threads with anti‑seize (very small amount) if manufacturer allows — some OEMs say do NOT use anti‑seize; check parts instructions. Better: use a small dab of copper paste if allowed.
- Fit any new crush washers/seals.
- Thread new glow plug in by hand to avoid cross‑threading. Use socket and torque wrench to final torque.
- Typical torque: approx 8–15 Nm (6–11 ft‑lb) depending on plug design — check the service manual for exact spec for your engine. Tighten to spec gently.

6) Reconnect electrical connections
- Clean contact surfaces with contact cleaner and wire brush.
- Reattach boots/connector; apply a small amount of dielectric grease to boots to prevent corrosion.
- Reconnect battery negative after all plugs installed.

7) Final checks
- Turn key to glow/preheat position and check that glow indicator behaves normally. Use multimeter to confirm 12V at plugs during preheat if desired.
- Start engine and check for smooth idle and no smoke abnormalities. Inspect for any fuel/water leaks or loose wiring.

Step‑by‑step: Replace glow relay/module (if required)
1) Locate relay — typically in engine bay fuse/relay box or near firewall. Consult manual or follow harness from glow plug circuit.
2) Test relay: with multimeter check for 12V on supply terminal, and activation output when preheat is switched. If supply present but no output, relay is faulty.
3) Remove relay: disconnect battery negative, pull connectors, unscrew mounting screws if any, swap in new part.
4) Reconnect and test: with battery connected, turn preheat on and verify output to glow plug harness (12V) and proper glow indicator operation.

Common pitfalls and how to avoid them
- Breaking a glow plug in the head: most common and costly. Avoid by using penetrating oil, heating the head, and slow controlled torque. If seized, do not use excessive impact.
- Cross‑threading new plug: always start by hand.
- Over‑torquing: use torque wrench; glow plugs are relatively light torque.
- Using wrong replacement plugs: match part by engine code and physical length/heat rating.
- Using too much anti‑seize: can alter torque; follow OEM guidance.
- Ignoring wiring/connectors: corroded connectors cause intermittent faults — clean or replace harness ends.
- Not testing relay: replacing plugs when relay is faulty wastes parts — test the relay first.

If a glow plug snaps and the tip remains in the head
- Stop; remove head if necessary for proper extract and thread repair.
- Attempt extraction only if you have the right extractor and experience; otherwise strip head and send to machine shop for drilling and helicoil/thread repair.

Quick diagnostic tips
- Dead cylinder/no start + amber glow light not lighting = suspect relay/fuse or wiring.
- Very rough cold start with white smoke from exhaust = failing glow plugs.
- One cylinder misfire/rough idle after glow plug change may indicate a damaged plug or connector.

Parts to order
- Correct glow plugs × number of cylinders (6 for 2H/12H‑T inline‑6)
- Glow relay/module (part number from parts catalog)
- Seals/washers, possibly new wiring boots

That’s it — follow steps in order, use the right socket and torque wrench, and don’t force seized plugs. If a plug breaks in the head or you’re uncomfortable extracting, stop and consult a machine shop.
rteeqp73