Turbocharger: Testing and Inspection

TURBOCHARGER - PHYSICAL INSPECTION

Checking Turbocharger Turbine/Impeller Wheel:

1. Be sure engine and exhaust are cool enough to touch.
2. Remove air inlet hose from turbocharger.
3. Spin impeller by hand and check that wheel assembly turns smoothly and freely and that impeller and turbine do not touch housings. If there is any bearing noise or friction, or if impeller or turbine contact housings, replace turbocharger.
4. Remove oil return line from turbo bearing housing.
5. Check that oil passage is not blocked by carbonized oil deposits. Replace turbo and oil return pipe if necessary.

TURBOCHARGER - BOOST PRESSURE CHECK

Method 1 - Stationary Vehicle

1. Disconnect vacuum/pressure hose from wastegate solenoid and connect to vacuum/pressure gauge.
2. Start engine and warm to operating temperature.
3. Slowly increase engine speed to 4000 rpm and note boost pressure on gauge.
4. Gauge should show slight positive pressure. If not, physically inspect turbocharger and wastegate. Also check intake and exhaust system for restrictions or leaks.

Method 2 - Test While Driving

1. Connect pressure/vacuum gauge to wastegate solenoid vacuum/pressure hose using a "tee" coupling, and an extra piece of hose long enough to reach to the passenger compartment. Make sure hose connections are secure so they will not separate under boost pressure.
2. Close hood and test drive vehicle (do not pinch gauge hose when closing hood). Accelerate hard from approximately 2500 rpm to approximately 4500 rpm in a middle gear. Have an assistant observe gauge pressure. Gauge should show positive pressure beginning at about 3000 rpm. Pressure should never exceed 8.7 psi (60 kPa).
3. If boost pressure is late, excessively low, or not present, check for the following:
^ Turbocharger bearing failure or turbine/impeller failure or damage.
^ Wastegate stuck open.
^ Air bypass valve stuck open.
^ Clogged air cleaner, or other intake restriction.
^ Restricted exhaust system or catalytic converter.
^ Exhaust leak at manifold or turbocharger.
^ Intake air leak between turbocharger and throttle body.

4. If boost pressure exceeds the maximum, check wastegate operation (wastegate may be stuck closed).


TURBOCHARGER - WASTEGATE OPERATIONAL CHECK

Checking Wastegate Operation:

1. Be sure engine and turbocharger are cool enough to touch.
2. Remove insulator covers to gain access to turbocharger.
3. Connect pressure regulator/gauge and apply air pressure regulated to 8.5 psi/60 kPa.

CAUTION: Do not apply air pressure greater than 14 psi (98kPa). Actuator diaphragm damage will result.

4. Check that wastegate lever and actuator rod (linkage rod) moves when connecting and disconnecting air pressure. If wastegate lever is rusty or sticking, a small shot of penetrating oil may free it.
5. Reconnect manifold pressure hose and recheck boost pressure if necessary.