Toyota started the production of 3.0 liter 3VZ-FE engine in 1987 as the new engine for Toyota 4Runner. This engine was installed in other off-road Toyota models in the future. The engine is similar to its predecessor the 2VZ engine, but the more significant displacement is not the one difference.The cast iron cylinder block looks the same, but it is taller by 20 mm (the height is 223 mm). The angle between cylinders in V-shape configuration of the block is 60 deg. Inside the block, there is new forged crankshaft with nine counterweights and 82 mm stroke.The early version of this engine 3VZ-E has SOHC aluminum cylinder heads and original pistons. The compression ratio of these engines is only 9.0:1. The redeveloped version and more performance engine the 3VZ-FE was produced from 1992 to 1997. The 3VZ-FE got aluminum DOHC heads with the increased diameter of the intake valves to 34 mm from 33 mm. The engine doesn't have hydraulic lifters. The shape of intake valves also was changed. 27.3 mm is the diameter of the exhaust valves. There are numbers for adjusting valve gaps: 0.25-0.35 mm intake, 0.15-0.25 mm exhaust.3VZ camshaft specs: duration - 230 intake 230 exhaust, 12 deg overlap, 7.85 mm intake lift (or .31"), 7.6 mm exhaust lift (or .30"). Timing belt drives the intake cams. The exhaust cam is driven by intake camshaft through gear in the middle of the cylinder head. The engine has variable geometry intake manifold called ACIS by Toyota. The exhaust system also was tuned and optimized.The engine was designed to be installed with 15 deg angle to use it in many applications. The manufacturer slowly replaced 3VZ-FE engine since 1994 by 1MZ-FE, but 3VZ got new life as the 3.4 liter 5VZ-FE in 1995.

Tools & supplies
- Spin wheel balancer (static/dynamic balancer) with correct shaft/adapters/cones (cone set, collets, hub-centric adapters).
- Tire changer & bead breaker (if tire removal required).
- Weight hammer, weight pliers (for clip-on), adhesive weight applicator or heavy roller.
- Wheel weight assortment (clip-on and stick-on/lead-free adhesive), cleaning solvent (isopropyl alcohol).
- Dial indicator with magnetic base (for radial/lateral runout checks).
- Torque wrench, lug wrench, jack and jackstands or 2-post lift, wheel chocks.
- Air compressor, tire gauge, valve core tool, replacement valve stems/cores, TPMS tool (if equipped).
- Gloves, safety glasses, shop rags.

Safety precautions
- Work on level surface. Chock opposing wheels. Use jackstands or a lift — never rely on jack only.
- Wear eye protection. Keep hands clear when machine is spinning.
- Verify vehicle wheel torque spec before reinstallation and use calibrated torque wrench.
- If wheel has TPMS, disable/protect sensor and use proper procedures to avoid damage.
- Check balancer speed limits and do not exceed recommended RPM.

Overview of process
You’re going to remove the wheel, inspect it, mount it correctly on the balancer (centered), enter wheel data, spin, apply weights where the balancer indicates, re-spin to confirm, and reinstall. If runout or tire damage is present, repair/replace before balancing.

Step-by-step

1) Prep and remove wheel
- Loosen lug nuts slightly with vehicle on ground.
- Raise vehicle with jack or lift and support with jackstands.
- Remove wheel. Note valve stem location (reference for weight placement if needed).

2) Inspect tire & rim
- Visual: bulges, cuts, tread separation, missing cord or belt separation; replace tire if damaged.
- Rim: bent, cracked, severe corrosion at mounting face — replace or repair rim if damaged.
- Check valve stem and TPMS. Replace leaking valve stem or faulty TPMS sensor before balancing.
- Clean wheel mounting surface and hub face of rust/paint/debris.

3) Decide on on-car vs off-car and dismount tire if necessary
- Off-car balancing (recommended): remove wheel assembly from vehicle and balance on spin balancer.
- If tire needs dismounting (repair or replacement), use tire changer, bead lubricant and follow safety for bead breaking. Replace valve stem if you remove tire.

4) Mount wheel to balancer correctly
- Choose the proper centering adapter (cone or hub-centric ring). For hub-centric wheels use hub ring to center on balancer to mimic car hub.
- Slide wheel onto balancer shaft and seat it with the cone or centering device. Hand-tighten nut to draw wheel firmly to the adapter. Then torque the balancer nut per balancer manual — wheel must be perfectly centered and tight.
- If wheel is lug-centered only, use appropriate adapters/pins or the balancer’s lug studs to ensure centering.

5) Enter wheel parameters into balancer
- Enter rim diameter and width, and select measurement unit (grams/ounces). Select alloy or steel if prompted (some machines change weight type/location).
- If machine has “static only” or “dynamic” options, use dynamic for modern tires/wheels.

6) First spin and readout
- Close hood/guard and start balancer spin.
- Read the machine’s display — it will usually show inner and outer weight locations and the quantity (e.g., Inner 20 g at 3 o’clock, Outer 10 g at 11 o’clock).
- Note any machine prompts about runout or high residual that suggest tire/wheel issues.

7) Prepare rim surfaces and apply weights
- Clean weight areas with alcohol to remove grease/dirt (especially for adhesive weights).
- For alloy wheels use adhesive stick-on weights: remove backing, position at indicated location on inner or outer barrel flat areas or the inner well. Press and roll firmly; use wheel weight roller if available.
- For steel rims use clip-on weights: position on outer bead seat location (machine will show location); use weight pliers/hammer to seat clip-on securely. Do not clip onto thin painted lips of some alloys (will damage and can slip).
- If the machine gives offset positions (e.g., between inner and outer), follow machine’s instructions for weight stacking.

8) Re-spin and confirm
- Re-tighten or re-seat wheel on balancer if needed, then re-spin.
- Machine should now show residual imbalance within tolerance (usually small, e.g., <4–6 g or <0.1 oz depending on machine). If still out, remove weights and repeat or check for runout.

9) Check runout if balance won’t settle
- If repeated spins don’t reach tolerance, mount dial indicator: measure radial (vertical) and lateral (side) runout of rim/tire assembly.
- Typical acceptance: radial & lateral runout <0.060" (1.5 mm) — if larger, wheel or tire may be bent/out-of-round. Options: replace wheel or tire, or try rotating tire on rim to a different position that minimizes runout and then rebalance.

10) Final steps and reinstall
- Remove wheel from balancer, torque wheel nut on balancer if required, remove adapters.
- Reinstall wheel on vehicle. Torque lug nuts in star pattern to OEM spec (consult service manual; typical truck torque ~80–100 ft-lb — verify exact spec).
- Re-check lug torque after initial road test (10–20 miles).
- If TPMS present, check sensor status and tire pressure.

How the balancer tool is used (practical details)
- Centering: The cone (or hub-ring) forces concentric seating so the wheel’s centerline aligns with the balancer shaft. A mis-centered wheel gives false readings.
- Nut/clamping: A draw nut pulls the wheel tight to the cone/hub. Hand-start, then snug to seat; finish to specified clamp torque on machine.
- Data input: Diameter and width change the machine’s calculation of balance point; entering wrong values produces wrong weight locations.
- Static vs dynamic unbalance: The balancer measures both—the display typically shows two numbers/locations: static (single-plane) and dynamic (dual-plane). Place indicated weights on inner and outer planes as directed.
- Readout orientation: Most machines show weight positions relative to valve stem (valve at 12 o’clock baseline) — know whether the graphic uses valve stem as 12 o’clock or 6 o’clock and apply weights accordingly.
- Adhesive weights: press and roll to ensure full contact; poor adhesion = weights falling off later.

Replacement parts commonly required
- Wheel weights (clip-on and stick-on).
- Valve cores or valve stems (rubber stems on older wheels often replaced).
- TPMS sensors (if damaged or old).
- Wheels or tires if bent, cracked, or belts exposed.
- Hub-centric rings for aftermarket wheels (if needed to center).

Common pitfalls to avoid
- Dirty hub/rim or paint between mounting surfaces — causes runout and false imbalance.
- Using wrong centering method (lug-centric vs hub-centric) — produces incorrect readings.
- Applying clip-on weights to delicate alloy lips — damages finish and can slip off.
- Forgetting to replace leaking valve stems or damaged TPMS sensors before balancing.
- Not checking runout when imbalance won’t correct — chasing weights on a bent rim wastes time.
- Overrelying on adhesive weights on high-corrosion rims — they fall off if surface not prepped.
- Improper lug torque and not re-torquing after road test — safety hazard.

Quick acceptance criteria
- Final residual imbalance within machine tolerance (typically a few grams/0.1 oz).
- No vibration at highway speeds on a road test.
- No missing/broken rim, no cord/exposed belts on tire.

If you want, tell me whether you’ll be using an off-car spin balancer or a bubble/on-car balancer and whether the vehicle has TPMS; I’ll give exact torque spec and any vehicle-specific notes.
rteeqp73

Short version: overdrive (OD) in your Toyota with the 3VZ‑FE is a high gear in the automatic transmission used for low RPM highway cruising. Typical OD problems are caused by bad solenoids, clogged/low fluid, a sticking valve body, or worn OD clutch/band. Below I explain how the system works, every major component you’ll encounter, what commonly goes wrong, and step‑by‑step procedures for the usual DIY repairs (solenoid/valve body/filter/fluid) and notes on deeper clutch/band rebuilds. Read everything before you start. No nonsense.

Why repair overdrive? What it does and why it fails
- Purpose: Overdrive is the highest gear (lowest engine RPM for a given road speed). It reduces engine rpm for fuel economy and less wear on the engine at highway speeds.
- Why it fails: OD operation is controlled hydraulically and electrically. Problems show as no OD (vehicle won’t upshift into OD), harsh or late OD engagement, slipping in OD, or transmission stuck in limp mode. Common causes: bad OD solenoid(s), contaminated/clogged fluid/filter, sticking valve body passages, worn OD clutch plates or band, bad speed/shift sensors, wiring or control module faults.

Analogy: The valve body is a busy traffic cop directing hydraulic flow (cars) into gears (lanes). Solenoids are electric gates the cop opens and closes. If gates stick or the cop’s map is dirty (contaminated fluid), cars end up in the wrong lane (wrong gear).

Major components you’ll deal with (what they are and what they do)
- Torque converter: fluid coupling between engine and transmission; multiplies torque at low speed. Contains lock‑up clutch used at cruising speeds. Problems here can mimic OD trouble (slipping, shudder).
- Planetary gearset (includes OD gear): the mechanical gears that provide different ratios, including overdrive. Engaged by clutches/bands.
- Overdrive clutch pack / OD band: steel plates and friction plates that lock the planetary gears into OD. If worn they slip or won’t hold.
- Valve body: hydraulic control center — contains many small passages and spool valves directing pressurized fluid to clutches. If spools stick, the transmission won’t shift correctly.
- Shift solenoids / OD solenoid: electrically‑operated valves that the transmission control (TCM/ECU) uses to activate specific hydraulic circuits (including OD). On many Toyota units the OD solenoid can be part of a solenoid pack mounted to/near the valve body.
- Governor (older designs) / vehicle speed sensors: measure vehicle speed and provide feedback. Faults here affect shift timing.
- Throttle Valve (TV) linkage / cable or kickdown cable: sets hydraulic line pressure/shift points based on throttle. Incorrect adjustment affects OD engagement and shifting.
- Transmission Control Module (TCM) / ECU: sends signals to solenoids based on speed, throttle position, temp. Faulty outputs or bad wiring can prevent OD.
- Fluid (ATF) & filter: fluid lubricates, cools, and transmits hydraulic pressure. Dirty or low fluid causes many faults.
- Wiring and connectors: power and ground to solenoids, sensor signals. Chafed wire or corroded connector = intermittent or total loss of OD command.

Symptoms mapped to likely causes
- No OD (won’t upshift to highest gear): bad OD solenoid, electrical fault, stuck valve, low/dirty fluid, worn OD clutch.
- Harsh or delayed OD engagement: low fluid, pressure loss, bad solenoid, valve sticking.
- Slipping only in OD: worn OD clutch/band, burnt fluid, low pressure.
- OD light on or transmission in limp mode: scan codes; could be solenoid failure/sensor/TCM.

Tools and parts you’ll need (basic)
- Service/repair manual for your exact vehicle/year (use factory manual for torque specs, fluid type, wiring diagrams)
- Basic hand tools, metric socket set, ratchet, torque wrench
- Jack, jack stands, wheel chocks (safety)
- Drain pan, funnel, rags
- Transmission fluid (use Toyota specified ATF — check manual; older Toyotas often use ATF Type T, newer use Type T‑IV)
- New transmission oil pan gasket (or RTV as specified), new filter, new pan bolts if needed
- Replacement solenoid or solenoid pack / valve body gasket(s) if you’re removing valve body
- Multimeter for electrical tests
- Transmission pressure gauge (for advanced diagnostics)
- Optional: OBD‑II scanner capable of reading transmission codes, vacuum gauges, parts cleaner, magnet pickup

Safety first
- Work on a level surface, use jack stands; never rely on a jack alone.
- Drain fluid carefully (hot), dispose/clean properly.
- Disconnect the battery before doing electrical work.
- When applying 12V to solenoids for bench testing, observe polarity and do brief pulses only.

Diagnose before you tear it apart — stepwise troubleshooting
1) Note symptoms precisely: when does it happen (cold, hot, only under load)? Any check engine/transmission light?
2) Scan for codes: use a scan tool and note any transmission or speed sensor codes. Write them down.
3) Check fluid: level and color/smell. Healthy ATF is red and transparent; brown/black or burnt smell = overheating/contamination. Low fluid = many shifting problems.
4) Visual inspection: wiring and connectors at the transmission, solenoid connectors, speed sensor connectors, and ground straps.
5) Basic electrical checks:
- With ignition ON, check voltage at solenoid connector (should have battery voltage on the feed). Use service manual for pinouts.
- Measure solenoid resistance across terminals with multimeter — compare to service manual. If wildly open or shorted, solenoid bad.
6) Functional test: with scanner, command OD solenoid on/off (if scanner supports it) and observe behavior or multimeter output.
7) Road test with scan tool connected: watch vehicle speed, engine RPM, commanded vs actual gear, solenoid activation. This shows if the TCM is commanding OD but it’s not responding (mechanical/hydraulic), or if TCM isn’t commanding it (electrical/control).

Simple fixes (most beginner-friendly)
A) Fluid and filter + pan gasket change (start here)
- Why: removes contaminants, replaces clogged filter, cures many valve sticking/low pressure problems.
- Steps:
1. Warm vehicle to operating temp (fluid flows better), park on level surface, set parking brake, chock wheels.
2. Lift with jack and support with stands.
3. Place drain pan. Remove bolts partway from transmission pan to let fluid drain from one corner (or remove pan depending on design).
4. Remove pan and clean magnet(s) inside pan (inspect for metal debris).
5. Remove old filter (usually held by bolts or just pressed in); inspect for excessive metal or burnt fragments.
6. Replace filter with new one and gasket/seal as required.
7. Clean pan and mating surfaces, install new pan gasket (or apply RTV per manual), torque bolts to spec.
8. Refill with specified ATF to correct level through dipstick or fill plug.
9. Start engine, cycle through gears with brake on, recheck level hot, road test.
- Result: many OD problems caused by grime/clog are fixed.

B) Replace OD/shift solenoid or solenoid pack (moderate)
- Why: solenoid fails electrically or mechanically, preventing OD engagement.
- Steps:
1. After doing A (fluid/filter), locate solenoid pack — often accessible with pan removed (on many Toyota transmissions the solenoid pack bolts to the valve body and is reachable without removing the transmission).
2. Disconnect battery, then unplug solenoid electrical connector(s).
3. Note and mark any wire locations; take pictures.
4. Remove bolts securing solenoid pack; carefully pull unit free. Be ready for some residual fluid to drip.
5. Install replacement solenoid or pack, new gasket/seals as required. Torque bolts to spec.
6. Reinstall pan/filter, refill fluid, reconnect battery.
7. Clear codes, start engine, test operation and road test.
- Electrical bench checks: measure resistance; if the solenoid has correct resistance in spec (check manual) but doesn’t operate when driven by vehicle, suspect wiring or TCM.

Valve body repair/cleaning (advanced for a beginner; moderate if you’re careful)
- Why: Valve body spools can get contaminated and stick, causing OD shift problems. Cleaning or replacing valve body can fix it.
- Steps (overview — follow service manual exactly; many small springs, balls, and parts):
1. Remove pan and valve body (valve body is typically held by bolts to the transmission case).
2. Keep track of bolt lengths and the order — take photos/label.
3. Carefully separate valve body; clean with solvent and compressed air. Do NOT damage valve bores or spool surfaces.
4. Inspect gaskets and replace all gaskets and seals.
5. Reassemble with new gaskets; bolt in place to proper torque pattern/spec.
6. Reinstall pan, refill fluid, test.
- Note: Valve bodies are delicate and precise; consider cleaning first and replace complete valve body or use a rebuilt unit if uncertain.

Deep repair: OD clutch/band replacement or full transmission rebuild (complex)
- Why: If OD still slips after fluid/filter/solenoid/valve body checks, clutch friction material may be worn or the band stretched; hydraulic pressure loss due to worn pump or internal seals may be present.
- Reality: This requires dropping the transmission, disassembling planetary sets, replacing clutches/bands, seals, and often the pump. It’s a multi‑day job and often better to send to a transmission shop or install a rebuilt transmission unless you have experience, proper tools (presses, snap ring tools) and service manual.
- Steps (high level): remove transmission, disassemble per manual, replace clutch plates, band, seals, inspect pump wear, measure clearances, reassemble with new gaskets and seals, torque everything to spec, adjust bands if required, refill fluid, test.

Diagnostic tests for deeper issues (pressure tests etc.)
- Line pressure test: attach pressure gauge to test port to confirm hydraulic pressure at idle and during shift. Low pressure indicates pump/wear or valve/pressure regulator problems.
- Solenoid activation test: with key on and engine running, command or observe solenoid activation with scanner while measuring voltage at harness.
- Oscilloscope or advanced scan data: check TCM commands vs actual solenoid state.

Common mistakes to avoid
- Assuming electrical is fine without checking voltage/ground at connector.
- Replacing solenoids without changing fluid/filter — contamination will ruin new solenoids.
- Using wrong ATF type — can affect friction materials and shift quality (check manual).
- Improperly torquing valve body/pan bolts or missing bolts — can cause leaks or internal damage.
- Not noting bolt locations — valve body bolts are often different lengths.

Post‑repair checks and break‑in
- After any fluid/pan/solenoid work: start engine, check for leaks, verify proper fluid level hot, cycle through gears with brake, and road test.
- If clutch packages were replaced: follow break‑in procedure (gentle driving, avoid full throttle for first few hundred miles) per manual.
- Clear codes and monitor with scan tool for hard codes or pending faults.

When to take it to a pro
- You don’t have the proper tools (pressure gauge, torque wrench, lift).
- Replacement requires removing the transmission or replacing clutch packs — unless you have transmission experience, a shop is advisable.
- If line pressure is low indicating pump wear — often a rebuild or replacement transmission is best.

Quick troubleshooting flow (do this in order)
1. Check fluid level/condition.
2. Scan for codes.
3. Visual/wiring check at solenoid harness and speed/throttle sensors.
4. Replace fluid and filter.
5. If problem persists, bench/measure solenoid resistance and connector voltage, then replace solenoid(s) if faulty.
6. If still a problem, inspect/clean valve body or replace valve body/solenoid pack.
7. If still unresolved or if slipping persists in OD only, plan for transmission removal/rebuild or replacement.

Final notes
- Get the factory service manual for your exact year/model — it contains pinouts, resistance specs, torque values, fluid capacity/type and step-by-step exploded views. Follow it.
- Keep records and take photos during disassembly — reassembly is much easier with photos.
- If you need a specific electrical pinout, solenoid resistance spec, or torque number, refer to the factory manual for that model/year — those are specific and must be exact.

That’s the full practical guide: how OD works, each component, what goes wrong, and how to repair common faults from easiest (fluid/filter) to hardest (clutch/band rebuild). Follow the checklist, use the manual, and don’t rush the valve body or internal work.
rteeqp73