Engine Noise: Turbocharger

A Turbocharger noise can be identified by one of the following:

1. A loud whine or whistle during acceleration 
   • This condition is most often the result of a loose clamp/hose at the Turbocharger compressor outlet, charge air cooler (CAC) inlet, CAC outlet or at the Intake Manifold. Some things to look for:
     1. With the engine running at idle, the Transmission in Park or Neutral, and with the parking brake set, feel for boost air escaping at each connection between the Turbocharger compressor outlet and Intake Manifold. For limited access areas, spray soapy water on those connectors and look for bubbles.
     2. Check the Exhaust Manifold and exhaust system for leaks.
2. Exhaust howling during turbo boost 
   • This condition usually occurs over a narrow speed range and may be caused by an issue with the muffler (usually external damage) bent touching frame or bent restricting exhaust flow.
3. Loud popping, whooshing , flushing, fluttering, noise emitted during closed throttle deceleration 
   • This condition is caused by inability of the engine to intake higher boost levels that are present at the beginning of closed throttle deceleration. Pressure generated by the Turbocharger has nowhere to go, thus causing it to "stall" or "surge". The noise will sound as though it is coming through the air cleaner, however this is a normal condition.  No damage will be sustained and the Turbocharger should not be changed for this condition.
4. Low boost pressure 
   • Low boost pressure is usually a symptom of low fuel injection pump fuel delivery and is associated low power complaints. Generally Turbocharger replacement will be related to turbine shaft failures or Turbocharger housing seal leaks. To check for turbine shaft bearing damage, perform the following checks:
     1. With the engine off, remove the air cleaner to Turbocharger intake tube.
     2. Visually inspect the Turbocharger compressor fan. The fan blades should not contact the fan housing and the fan blades should not be chipped, bent or damaged in any way.
     3. Check the end play of the compressor to fan. A small amount of fore/aft play is normal. Excessive play that would cause fan distortion or fan to housing contact is not acceptable. In this case, replace the Turbocharger.
     4. While pushing the turbine shaft left, right, up and down, gently rotate the compressor wheel. The compressor fan should turn freely by hand, if it doesn't replace the turbocharger.