Turbocharger Toyota 4Runner I

DESCRIPTION

The Toyota turbocharger unit consists of turbine and compressor impellers, impeller shaft, bearings and impeller housings. The turbocharger is equipped with a wastegate to prevent engine damage from excessive boost pressure. The wastegate opens to prevent excessive intake boost pressure.

The turbine impeller of the turbocharger is driven by the exhaust gases expelled from the cylinder combustion chambers. At idle speeds the engine operates like a normally aspirated engine. As engine speed increases with opening of the throttle valve, the amount of exhaust gas increases. This leads to an increase in the rotational speed of the turbine. The turbocharger is lubricated by engine oil. Lubricating oil is essential in cooling the turbocharger to prevent bearing failure.

Exploded View of Turbocharging System Camry turbocharging system is shown, Pickup system is similar. Scheme 94

PRESSURE CHECK

1. Connect a 3-way union to boost compensator pressure hose and install a pressure gauge to it. While driving with engine running at 2500 RPM or more (accelerator pedal fully depressed in first gear), check the turbocharging pressure. Standard pressure is 7.7-9.7 psi (.54-.68 kg/cm 2 ) for Camry and 5.8-7.7 psi (.41-.54 kg/cm 2 ) for Pickup.
2. If pressure is less than specification, first check intake air and exhaust systems and relief valve for leakage. If there is no leakage, replace turbocharger assembly. If pressure is above specification, first check if the actuator hose is disconnected or cracked. If not, replace turbocharger assembly.

INTAKE AIR SYSTEM

Check for leakage or clogging between the air cleaner and turbocharger inlet and between turbocharger outlet and cylinder head. If air cleaner is clogged, clean or replace element. Repair or replace any collapsed or deformed hoses. Check and repair any leaking connections. Check and replace cracked components.

EXHAUST SYSTEM

Check for leakage or clogging between the cylinder head and turbocharger inlet and between the turbocharger outlet and exhaust pipe. Repair or replace deformed components. Remove foreign material in passages. Repair or replace leaking and cracked components.

ACTUATOR & WASTEGATE

Disconnect actuator hose. Using a pressure gauge, apply 8.2-8.7 psi (.58-.61 kg/cm 2 ) of pressure to actuator hose and check that rod moves .0098" (.25 mm) or more. If less, replace turbocharger assembly.

IMPELLER WHEEL ROTATION

Disconnect air cleaner hose. Grasp edge of impeller wheel and turn it. Verify that it turns smoothly. If it does not turn or if it turns with drag, replace turbocharger assembly.

RELIEF VALVE

Check outside of relief valve for excessive oil oozing. If no oil oozing is found, the relief valve is okay. If oil oozing is found, replace the relief valve and check the performance. If there is no change in performance, the relief valve is okay.

Insufficient Turbocharging Pressure

Check turbocharging pressure as outlined in PRESSURE CHECK in this article. If not within standard 7.7-9.7 psi (.54-.68 kg/cm 2 ), begin diagnosis starting with INTAKE AIR SYSTEM.

Unbalanced Air Intake System

Visually inspect air intake system. Ensure all hose and wire connections are clean and tight. Repair or replace parts as necessary.

Unbalanced Exhaust System

Inspect the exhaust system and note damaged or deteriorated sections. Check for leaks by restricting end of tailpipe and listening for leaks along the exhaust system. Repair or replace parts as necessary.

Relief Valve Leaking

Check for oil oozing around outside of relief valve. If not, relief valve is okay. If oil is present, check performance of relief valve and replace if necessary.

Check rotation of impeller wheel. If it does not turn or turns with heavy drag, replace turbocharger assembly. Check axial play of bearing shaft. If not within .0051" (.13 mm), replace turbocharger assembly.

Check for loose, improperly installed or deformed insulator mount bolts, and repair or replace as necessary.

Exhaust Pipe Leaking or Vibrating

Check for deformed exhaust pipe, loose mount bolts or damaged gasket, and repair as necessary.

Check rotation of impeller wheel. If it does not turn or turns with heavy drag, replace turbocharger assembly. Check axial play of bearing shaft. If not .0051" (.13 mm), replace turbocharger assembly.

Check for oil leakage in exhaust system. Remove turbine elbow from turbocharger and check for excessive carbon deposits on turbine wheel. Excessive carbon deposits would indicate a faulty turbocharger. Check for oil leakage in intake air system. Check for axial play in impeller wheel, and replace turbocharger if necessary.

Indicator Light & Warning Light Operation

1. Verify that Green indicator light and Amber warning light illuminate when ignition is turned on. If not, check 7.5A "GAUGE", "CHG" and "IGN" fuses. If fuses are blown, check for short and repair as necessary. If the fuses are okay, check to see if discharge warning light is out. If it is okay, the charging system is faulty. If the light is out, the combination meter is faulty.
2. If Green indicator and Amber warning lights illuminate when ignition is turned on, check to see if indicator and warning lights are out during engine idle. If both lights and discharge warning light are on, the charging system is faulty. If both lights stay on and discharge warning light is off, go to step 4).
3. If Green light stays on, check for open circuit in wire harness between low pressure switch and combination meter. If circuit is okay, replace faulty low pressure switch. If Amber light comes on, check for open circuit in wire harness between high pressure switch and combination meter and check for ground connection of switch. Repair either circuit as necessary.
4. If both indicator and warning lights are out during engine idle, check to see if Green indicator light comes on when 2 psi (.14 kg/cm 2 )) pressure is applied to both pressure switches. If Green indicator does not come on, check for short circuit in wiring harness between low pressure switch and combination meter. If circuit is okay, replace faulty low pressure switch.
5. If Amber light comes on, see if Green indicator light comes on when 11.9 psi (.84 kg/cm 2 ) pressure is applied to both switches. If not, replace faulty high pressure switch. If it does come on, combination meter is faulty.
6. If the Green indicator light does come on when the pressure in step 4) is applied, check to see if Amber indicator light comes on when 11.9 psi (.84 kg/cm 2 ) is applied to both switches.
7. If not, check for short circuit in wire harness between high pressure switch and combination meter. If no short circuit is present, replace faulty high pressure switch. If Amber light does light when pressure is applied, turbocharger indicator and warning light operation are okay.

Removal

1. Disconnect negative battery cable. Drain coolant. Disconnect oxygen sensor wire and connector. Disconnect PCV hose from cylinder head cover. Loosen clamp and disconnect air cleaner hose from turbocharger.
2. Remove 4 clips and remove air cleaner hose with air cleaner case cover. Disconnect turbocharger pressure hose to compressor elbow. Loosen clamp and disconnect air intake hose from intake manifold.
3. Remove bolt holding elbow stay to engine. Remove 2 bolts and compressor elbow with relief valve and air intake hose. Remove compressor elbow gasket. Remove turbocharger heat insulators. Remove 3 nuts from flange. Disconnect exhaust pipe from manifold and remove gasket.
4. Remove turbocharger oil pipe flange nuts. Remove 4 nuts and remove turbocharger, turbocharger gasket and flange gasket from exhaust manifold. Remove 4 nuts, washers, turbine elbow and gasket. Remove relief valve from compressor elbow.

Inspection

1. To inspect impeller wheel rotation, grasp edge of turbine wheel and turn it. Check that impeller wheel turns smoothly. If impeller wheel does not turn or if it turns with a drag, replace turbocharger assembly.
2. To inspect axial play of shaft bearing, insert a dial gauge into intake side, hold turbine wheel edge by hand and check axial play. Standard clearance is .0051" (.13 mm). If not within specification, replace turbocharger assembly.

Installation

Note. After replacing a turbocharger assembly, pour 20 cc of new oil through oil inlet while turning impeller wheel to splash oil on bearing.

1. Install relief valve to compressor elbow and tighten nuts to 27 ft. lbs. (37 N.m). Install gasket and turbine elbow with 4 nuts and washers and tighten nuts to 18 ft. lbs. (25 N.m). Place a new gasket with protrusion on opposite side of cylinder head.
2. Install turbocharger, with a new oil pipe gasket, to exhaust manifold and oil pipe. Install nuts and tighten to 38 ft. lbs. (52 N.m). Install turbocharger oil pipe flange nuts and tighten to 13 ft. lbs. (18 N.m). Place a new gasket on exhaust pipe.
3. Connect exhaust pipe and install flange nuts. Tighten to 9 ft. lbs. (13 N.m). Install turbocharger heat insulators. Install compressor elbow with relief valve and air intake hose with 2 bolts and new gasket. Tighten bolts to 9 ft. lbs. (13 N.m).
4. Connect elbow stay to engine. Connect air intake hose to intake manifold with clamp. Connect turbocharger pressure hose to compressor elbow. Install air cleaner case cover and air cleaner hose with 4 clips. Connect air cleaner hose to turbocharger with clamp. Connect PCV hose to cylinder head cover.