1. Every turbo has its own noise level when operating. If the noise level changes, suspect a problem.
If the sound of the turbo goes up and down in pitch:
a) Check for heavy dirt build up in the compressor housing and on the compressor wheel.
b) Check for an air inlet restriction.
If the noise level is a high pitch or whistling:
c) Look for an inlet air or exhaust gas leak.

2. With the engine off and the turbo stopped, make a visual inspection of the turbo and components.
3. Check for loose duct connections from the air cleaner to the turbocharger.
4. Be sure the duct from the turbo to intake system is not loose.
5. Visually check the wheels of the turbo for damage from foreign objects.
6. Look for evidence of wheel-to-housing contact.
7. Be sure the shaft rotates freely. Rotating stiffness could indicate the presence of sludged oil or coking (hardened oil deposits) from overheating.
8. Push in on one of the shaft wheels while turning it. Be sure the wheels turn freely without contacting the housings,
9. Be sure the exhaust manifold has no loose connections or cracks.
10. Check the oil drain line for any restrictions.
11. Visually inspect the actuator and wastegate linkage for damage.
12. Check the hose to the wastegate.