Tools & supplies
- Metric socket set (8–14 mm), ratchet, extensions
- Flathead & Phillips screwdrivers
- Needle-nose pliers
- 10–12 mm open wrench (for fittings)
- Multimeter (DC ohms & volts)
- Hand-held vacuum pump with gauge (for vacuum-type valves)
- 12 V power supply / jumper leads with fused inline lead (for bench-actuation)
- Small soft-bristle brush, carb cleaner or electrical contact cleaner
- Clean rags, disposable gloves, eye protection
- Replacement auxiliary air valve (AAV) and O‑ring/gasket kit (OEM recommended)
- Small container for bolts, hose clamps, etc.; dielectric grease
- Anti-seize (optional for threads), torque wrench (if you have torque specs)

Safety precautions
- Work on a cool engine. Hot intake manifold or turbo components will burn.
- Disconnect negative battery terminal before disconnecting electrical connectors or removing components.
- Work in a well-ventilated area; avoid inhaling cleaners.
- Use eye protection when spraying cleaners or testing with vacuum/12 V.
- If you raise the vehicle, use jack stands — never rely on the jack only.

What the job is and where to find the part
- The auxiliary air valve (AAV) on older Toyota B / 2B engines is mounted on or near the throttle body/intake manifold. It provides bypass air during cold start or is vacuum/thermally controlled to stabilize idle. Confirm by visual inspection: a small cylindrical valve with 1–2 vacuum hoses or an electrical connector.

Step-by-step removal
1. Prepare
- Park on level ground, engine cold. Disconnect negative battery.
- Label and photograph hose routing and electrical connector to ensure correct reassembly.

2. Access & clear working area
- Remove air cleaner assembly or ducting that blocks access to the throttle body and AAV.
- Loosen clamps and hoses as needed to move the air box without disconnecting mass airflow sensor.

3. Disconnect vacuum hoses/electrical connector
- Use needle-nose pliers to remove spring clamps, then twist and pull vacuum hoses off. Replace brittle hoses.
- Depress tab and unplug the electrical connector. If frozen, gently pry with a small screwdriver, protecting the plastic.

4. Remove mounting fasteners
- Remove the bolts holding the AAV to the throttle body/intake (usually 2–3 bolts, 8–12 mm).
- Keep bolts and any spacers/studs in your parts container. Remove the valve straight out to avoid tearing the O‑ring.

5. Inspect
- Check O‑ring/gasket and mating surfaces. If O‑ring is flattened, cracked or hard, replace it.

Bench testing (identify which type you have first)
A) Electrical/thermostatic AAV (has 2 wires)
- Measure coil resistance with multimeter across the two pins. Typical value varies by design (often 20–100 ohms). If open/infinite, coil is bad.
- With AAV cold: apply 12 V through a fused jumper to the connector (ground to valve body). Many thermostatic AAVs are heat-activated and will change state with temperature — on bench you may not see movement unless you heat the valve (hot water bath) to simulate engine temp. Do not immerse electrical connector; mask it and only submerge the cast body if safe.
- Expected: valve should actuate or change resistance with temperature (consult manual for exact behavior). If it does not, replace.

B) Vacuum-operated AAV
- Attach hand vacuum pump to the port and apply vacuum. The valve should hold vacuum (no leaks) and either open or close flow as specified (you can blow through while applying vacuum to check passage).
- If it won't hold vacuum or actuate, replace.

Cleaning (only when mild carbon/soot is present)
- Use carb/air intake cleaner and soft brush to remove deposits from valve mating face and internal visible areas. Do not spray high-pressure into electronic parts.
- Replace O‑ring/gasket. Lightly coat new O‑ring with clean engine oil or dielectric grease.

Reinstallation
1. Fit new O‑ring/gasket into groove. Ensure mating surface is clean and flat.
2. Install AAV onto manifold, align, and start bolts by hand. Tighten evenly to snug. If torque spec is unknown, tighten to light torque — snug + 1/8–1/4 turn. Avoid over-torquing (aluminum threads strip easily).
3. Reconnect vacuum hoses (replace damaged hoses/clamps) and electrical connector. Apply a small smear of dielectric grease to electrical terminals.
4. Reinstall air cleaner and ducting.
5. Reconnect negative battery terminal.

Verification & final checks
- Start engine cold. Observe idle behavior and listen for hissing leaks. On thermostatic AAV, idle should be higher when cold and settle as engine warms. On vacuum AAV, verify vacuum hoses are not collapsing and system holds vacuum.
- Scan for engine codes if vehicle has ECU; clear codes if needed and check for reoccurrence.
- Road test and recheck for leaks or loose fittings.

Common pitfalls & how to avoid them
- Tearing brittle vacuum hoses: always inspect and replace old vacuum lines when removing. Use correct diameter hoses.
- Losing O‑ring or reusing a damaged seal: always replace O‑ring/gasket.
- Damaging electrical connector pins: depress tabs fully and pull straight; use small pick to release locks if needed.
- Over-torquing fasteners into aluminum: tighten snug, do not force; use torque wrench if you have spec.
- Misrouting vacuum hoses on reassembly: mark or photograph original routing before removal.
- Misdiagnosing: test valve on bench — replacement is often needed if electrical coil is open or vacuum diaphragm leaks. Don’t replace spare parts without testing.
- Using 12 V on an electronic thermally-controlled AAV without fused lead: always fuse jumper to avoid burning out coil.

Replacement parts required
- Auxiliary air valve assembly (OEM or quality aftermarket) if valve fails bench tests or is physically damaged.
- O‑ring/gasket kit for AAV mounting (recommended every time you remove).
- Vacuum hose(s) and clamps if brittle, cracked, or collapsed.
- Electrical connector or terminals if corroded/damaged.

Tool usage details
- Multimeter: set to ohms to check coil continuity; set to DC volts to check for 12 V at connector with ignition on (engine cold). Back-probe connector carefully with ignition on, respecting safety.
- Vacuum pump: connect to valve port, pump to specified vacuum (hand pump gauge shows vacuum). Watch whether valve holds vacuum and actuates. A leaking diaphragm indicates replacement.
- 12 V power supply/jumper: use fused lead (1–3 A fuse inline) to bench-actuate coil briefly. Never apply continuous power for long periods; heat may be part of its operation so bench test may require heating per manufacturer notes.

Closing
- Replace the valve and O‑ring if bench tests show open coil, stuck mechanism, or vacuum leak. Re-test after installation. If idle or emissions problems persist after a functional AAV, inspect intake leaks, throttle body, and idle control systems.

End.
rteeqp73

How to Toyota b2 diesel engine start, Toyota b3 engine How to Toyota b2 diesel engine start, Toyota b3 engine.

Comparison of diesel engines 3C and 3L In this video, we will try to compare two diesel engines from Toyota #3L #3C #2c The Toyota 3C and 3L diesel engines are both ...

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