Usage:
Caterpillar Truck Engines Equipped With ATAAC
Reference: Truck Engine News, May 1987, Page 6, "Stop Engine If There Is A Turbocharger Bearing Failure ".
Reference: Truck Engine Installation And Application Guide, Form LEBT8121. Service Manual, 3406B Diesel Truck Engine, Form SEBR0544-03.
To insure and maintain the factory specif ied engine performance (with regard to power, fuel economy, emissions, smoke, etc.) both the ambient air and charge air sides of the air-to-air aftercooler must be clean.
Location of air system components. (1) Air-to-air aftercooler core. (2) Air cleaner. (3) Turbocharger. (4) Exhaust manifold. (5) Intake manifold.
A visual inspection can determine if the ambient air side of the aftercooler needs cleaning. The fins and tubes of the aftercooler core are made from very thin copper or aluminum material. Compressed air, soap and water, and a soft brush can be used CAREFULLY to remove dust and debris from the cooler core fins.
The cleanliness of the charge air side of the aftercooler can be determined by a pressure drop measurement. When the total pressure drop between the turbocharger outlet and the inlet manifold, at maximum air flow exceeds 13.5 kPa (4 in Hg), the air line and cooler core must be cleaned and inspected.
To clean the aftercooler core it must be removed. Use standard shop solvents to remove oil and other foreign substances from the inside of the core. Shake the core to eliminate any trapped debris. Wash the core with hot, soapy water, and rinse thoroughly with clean water. Use compressed air, blown in the reverse direction of normal air flow, to dry the core. Carefully inspect the core to make sure it is clean.
NOTE: Also, check the turbocharger compressor wheel. If only the blade side of the wheel is dirty, dirt and/or moisture is passing through the air filtering system. Oil found on only on the back side of the wheel indicates a turbocharger oil seal leak. The leak is probably the result of extended engine operation at low idle and/or plugged air filter elements. This can lead to contamination of the entire downstream air system. Many air systems need compressor wheel/housing maintenance at the mid-life turbocharger inspection. Clean the compressor wheel and housing with standard shop solvents and a soft bristle brush.
NOTE: Do NOT operate the engine if there is a turbocharger bearing failure because serious engine damage may result. See the Reference Article.
An aftercooler core leak can also result in low power, low boost pressure, excessive smoke, etc. The Reference Service Manual describes the procedure for checking the aftercooler core for leakage. This procedure requires the FT1984 Air To Air Aftercooler Test Group. See your Caterpillar dealer for additional information about these tools or for drawings of the Fabricated Tools.
The total air to air aftercooler system performance must be tested to confirm that the specifications for the particular engine and rating are satisfied. The Reference Truck Engine Installation And Application Guide contains detailed information for evaluation of the system.