Troubleshooting on the exhaust turbocharger

INTRODUCTION: 

For charged engines, exhaust turbochargers are of significant importance to the power development. The turbochargers deliver the charging pressure that is required by the engines. Depending on the system (one-phase or multi-phase), one or more turbochargers are installed. However, the function of the turbocharger greatly depends on the proper function of other components in the periphery.

This document describes the sources of fault on the actual exhaust turbocharger as well as the factors influencing and causing faults in the periphery.

The following pictures show examples for the schematic structure of one-phase or multi-phase systems with the subsequently required actuators.

Courtesy of BMW OF NORTH AMERICA, INC.

Courtesy of BMW OF NORTH AMERICA, INC.

Courtesy of BMW OF NORTH AMERICA, INC.

GENERAL NOTES ON TROUBLESHOOTING: 

The following notes must be observed in order to find the root cause of faults when problems are reported, and to prevent the unauthorized, i.e. inappropriate, replacement of the exhaust turbocharger:

1. Tracking down and verifying the complaint 

   If possible, any problem reported ('complaint') should be tracked down and verified on the vehicle. The parameters or marginal conditions prevailing at the time the problem was reported need to be noted down.

2. Diagnosis 

   As a first procedural step, diagnosis must be performed using the diagnosis system.

   Faults on sensors and actuators may be responsible for 'complaints', i.e. reported problems, which may also be associated with the exhaust turbocharger in some way. For this reason, faults on sensors and actuators must first be remedied if these are stored in the fault memory. In addition, the engine ventilation is important for the oil supply to the exhaust turbocharger. If the pressure in the crankcase is too high, the oil supply to the exhaust turbocharger is endangered, and oil leakage may occur at the exhaust turbocharger.

   After that, the charge pressure faults saved must be investigated, or troubleshooting must take place on the exhaust turbocharger.

3. Repair history 

   If possible, check to find out whether repairs have already been made on or near the exhaust turbocharger following similar reported problems.

   • With any repeated complaint with different fault patterns, the problem could have arisen during the last repair. Problems could have arisen in conjunction with installation, connections or the ingress of foreign bodies.
   • In the event of identical complaints, it is highly probable that the actual cause of the fault has not been remedied.

CAUSES: 

1. Leaks
2. Noise
3. Lack of power

NOTES ON THE INSTALLATION OF AN EXHAUST TURBOCHARGER: 

Before installation: 

• Prior to the installation of an exhaust turbocharger, fill engine oil in the oil inlet in the exhaust turbocharger. At the same time, rotate the shaft on the exhaust turbocharger.
• Check the oil supply to the turbocharger and the oil return from the turbocharger for foreign bodies and oil sludging, clean if necessary.
• Ensure that no dirt and no foreign bodies enter the openings.
• Clean the charging air system.
  NOTE: Do not leave any oil residue or foreign bodies in the charging air duct.
• Replace gaskets, and ensure that the gaskets are installed correctly.
• Observe tightening torques.

After installation: 

• Start up engine and run it at idle speed for at least one minute to ensure that the exhaust turbocharger is receiving a proper oil supply. When the engine is cold and the ambient temperature is low, let the engine idle for approximately 2 minutes.
• Check 'tightness', i.e. seal integrity, of the engine oil pipes.
• Shut down the engine and check the oil level.