300 Diesel Technology Copyright Goodheart-Willcox Co., Inc. ❑ Blue smoke. ❑ Excessive engine oil consumption. ❑ Noisy turbocharger operation. A lack of engine power and black smoke can both result from insufficient air reaching the engine and can be caused by restrictions in the air intake or air leaks in the exhaust system or the induction system. The first step in troubleshooting a turbocharger on a modern diesel engine is to look for a check engine (CEL) or stop engine light (SEL). If either light is on, connect the appropriate diagnostic scan tool to the unit and check the fault codes. Repair all defects related to the fault codes prior to trou- bleshooting the turbocharger. Once all fault codes are repaired or if there are no faults, start the engine and listen to the sound the turbocharging system makes. As a technician becomes more familiar with this characteristic sound, he or she will be able to identify an air leak between an engine and a turbocharger by a higher pitched sound. If the turbo sound cycles, or changes in intensity, a plugged air cleaner, loose material in the com- pressor inlet ducts, or dirt buildup on the compressor wheel and housing may be the cause. After listening to the system, check the air cleaner for a dirty element. If in doubt, measure for restrictions according to the engine manufacturer’s recommendations. The next step is to stop the engine and remove the ducting between the air cleaner and the turbocharger in order to look for dirt buildup or damage. Also, check for loose clamps on the compressor outlet connections and inspect the engine intake system for loose bolts, leaking gaskets, etc. Disconnect the exhaust pipe and look for restrictions or loose material. Examine the engine exhaust system for cracks, loose nuts, or blown gaskets. Checking the Turbocharger Rotate the turbo shaft assembly. It should rotate freely without signs of rubbing or wheel impact damage. There is normally radial shaft play in the turbo shaft assembly. However, if either of the wheels touches the housing when the shaft is rotated by hand, excessive play is indicated. If none of these symptoms are present, the low power com- plaint is probably not being caused by the turbocharger. Consult engine manufacturer’s troubleshooting procedures in this case. Checking for Oil Consumption Blue smoke is an indication of oil consumption and can be caused by either turbocharger seal leakage or internal engine problems. First, check the air cleaner for restrictions per the engine manufacturer’s instructions. Excessive air cleaner restriction can cause compressor oil seal leakage. Next, stop the engine, remove the turbo ducts, and check the shaft assembly for free rotation, rub- bing, and damage. Inspect the oil drain line for restrictions or damage, which can cause seal flooding and leakage. Also, check for high crankcase pressure. If in doubt, mea- sure the crankcase pressure. It must be within the engine manufacturer’s specifications. Finally, loosen the exhaust manifold duct and check for oil in the engine exhaust. If oil is present, refer to the engine manual for appropriate repair procedures. If there is excessive oil consumption without smoke, check the air cleaner for restrictions. Inspect the com- pressor discharge duct for loose connections, check the crankcase pressure, and examine the turbo shaft assembly for free rotation. Also, look for evidence of the wheels rub- bing on the housing walls. If no fault is found, consult the engine manual for further troubleshooting procedures. In the case of a noisy turbocharger, inspect all pres- sure connections for tightness—compressor discharge ducting, exhaust manifold, etc. Check the turbocharger shaft for looseness, look for evidence of wheel rubbing, and inspect the blade for impact damage caused by foreign material. If evidence of rubbing or impact damage is found, replace the turbocharger. Turbocharger Removal and Installation To remove a turbocharger, proceed in the following manner: 1. Loosen the connector clamp and position the flexible connector so that the crossover tube or charge air cooler connection can be removed, Figure 13-35A. 2. Disconnect the drain tube from the bottom of the turbo- charger, Figure 13-35B. 3. Remove the turbocharger drain line from the drain tube in the cylinder block, Figure 13-35C. Then remove the oil supply line. 4. Disconnect all electrical and oil connections to the VGT control piston, if applicable. 5. Remove the boots, exhaust clamp, turbocharger, and gasket, Figure 13-35D. If a turbocharger must be rebuilt, take it to a shop that specializes in this type of work. To install a new or remanu- factured turbocharger, simply reverse the removal proce- dure. Prime the turbocharger before engine start-up by removing the oil supply inlet fitting and adding approxi- mately .5 pint (.235 L) of clean engine oil to the turbo- charger, Figure 13-36. Operate the engine at low idle for a few minutes before operating it at higher speeds. Finally, check the system for leaks. Special Turbocharger Precautions Even the best engines and turbochargers will not perform optimally if the operator is not trained to use them properly. Turbocharged engines require proper shut- down procedures to prevent bearing damage. If the engine is shut down from high speed, the turbo will con- tinue to rotate after engine oil pressure has dropped to zero. Always idle the engine for several minutes before shutting it down.