BODY AS-PISTON 4787472 - Caterpillar

Hot engine components can cause injury from burns. Before performing maintenance on the engine, allow the engine and the components to cool.
Note: The turbocharger is a nonserviceable item. The pressure for the wastegate can be checked but not adjusted.Before the wastegate is tested, be sure that the inlet air restriction is within the specifications for your engine. Be sure that the exhaust system restriction is within the specifications for your engine. Refer to Systems Operation, Testing and Adjusting, "Air Inlet and Exhaust System - Inspect".Inspection of the Wastegate
The wastegate controls the amount of exhaust gas that is allowed to bypass the turbine side of the turbocharger. This valve then controls the rpm of the turbocharger.When the engine operates in conditions of low boost, a spring presses against a diaphragm in the canister. The actuating rod will move and the wastegate will close. Then, the turbocharger can operate at maximum performance.When the boost pressure increases against the diaphragm in the canister, the wastegate will open. The rpm of the turbocharger becomes limited. The rpm is limited because a portion of the exhaust gases bypass the turbine wheel of the turbocharger.The following levels of boost pressure indicate a problem with the wastegate:
Too high in full load conditions
Too low in all low boost conditionsThe boost pressure controls the maximum rpm of the turbocharger, because the boost pressure controls the position of the wastegate. The following factors also affect the maximum rpm of the turbocharger:
The engine rating
The horsepower demand on the engine
The high idle rpm
Inlet air restriction
Exhaust system restrictionTest the Wastegate for Proper Operation
Remove the heat shield from the turbocharger. Remove the guard for the wastegate.
Remove the boost line from the wastegate. Connect an air supply to the wastegate that can be adjusted accurately.
Fasten a suitable dial gauge to the turbocharger so that the end of the actuator rod is in contact with the plunger of the dial gauge. The dial gauge will measure axial movement of the actuator rod.
Slowly apply air pressure to the wastegate so that the actuator rod moves 2 mm (0.07874 inch). The air pressure should be approximately 168 kPa (24.3667 psi). Ensure that the dial gauge returns to zero when the air pressure is released. Repeat the test several times. This will ensure that an accurate reading is obtained.
Consult your nearest approved Caterpillar dealer or your nearest approved Caterpillar distributor if the operation of the wastegate is not correct.