Turbocharger: Testing and Inspection
TURBOCHARGER - PHYSICAL INSPECTION
Checking Turbocharger Turbine/Impeller Wheel:
1. Be sure the engine and exhaust are cool enough to touch.
2. Remove the air inlet hose from the turbocharger.
3. Spin the impeller by hand and check that wheel assembly turns smoothly and freely and that impeller and turbine do not touch the housings. If there is any noise or friction from the bearings, or if either the impeller or turbine contact the housings, replace turbocharger.
4. Remove the 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 up to normal operating temperature.
3. Slowly increase engine speed to 4,000 rpm and note boost pressure on gauge.
^ 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 "blow" apart under boost pressure.
2. Close the hood and test drive vehicle (careful not to pinch the hose to the gauge when closing the hood). Accelerate hard from approx. 2,500 rpm to approx. 4,500 rpm in a middle gear, while a passenger/partner observes the pressure on the gauge.
^ Gauge should show positive pressure beginning at approx. 3,000 rpm and pressure should never exceed 8.7 psi (60 kPa).
If boost pressure is late, excessively low, or not present, check for the following:
a. Turbocharger bearing failure or turbine/impeller failure or damage.
b. Wastegate stuck open.
c. Air bypass valve stuck open.
d. Clogged air cleaner, or other intake restriction.
e. Restricted exhaust system or catalytic converter.
f. Exhaust leak at manifold or turbocharger.
g. Intake air leak between turbocharger and throttle body.
If boost pressure exceeds the maximum, check wastegate operation (wastegate may be stuck closed).
TURBOCHARGER - WASTEGATE OPERATIONAL CHECK
1. Be sure the engine and turbocharger are cool enough to touch.
2. Remove the insulator covers to gain access to the turbocharger.
3. Connect pressure regulator/gauge to the wastgate actuator diaphragm, and apply air pressure regulated to between 7.0 - 8.5 psi/48 - 59 kPa.
CAUTION: Do not apply air pressure greater than 14 psi (98kPa). Damage to the actuator diaphragm will result.
4. Check that wastegate lever and actuator rod (linkage rod) move 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.