Technical Service Bulletins

Fixing a Rattling Cadillac

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Inspect the converter bracket nuts for looseness. If loose, replace with torque prevailing nuts.

Some owners of 2016-2019 Cadillac ATS or 2014-2019 CTS Sedan vehicles equipped with a 3.6L engine may comment about a brief rattle or ticking noise when revving the engine in Park/Neutral, and/or during acceleration/deceleration in Drive. The same noise can sometimes be heard when cold but goes away when warm.

The condition may be caused by loose converter bracket nuts or a possible issue with the turbocharger wastegate actuator arm.

Inspect the 8mm nuts that secure the catalytic converters to the exhaust bracket. If the nuts are loose, replace them with new torque-prevailing nuts. If the nuts are found to be tight, proceed to inspecting for a loose wastegate actuator arm.

CAD02.jpgRemove the actuator arm retainer that secures the arm to the wastegate.


Remove Bank 1 and Bank 2 turbocharger heat shields. Inspect the part number on the turbocharger. If P/N 12658344 or 12658345 is currently installed, replace the turbocharger and install cup springs. If neither part number turbo is found, install cup springs.

Remove the actuator arm retainer that secures the wastegate actuator arm to the wastegate valve. Remove the actuator arm from the wastegate valve. Install the cup spring washer (P/N 12686941) onto the wastegate valve with the concave side facing up. Install the wastegate actuator arm to the shaft.

Install the arm retainer and reinstall previously removed components.

CAD03.pngThe diagram shows the 1) actuator arm; 2) spring cup washer with concave side up; 3) arm retainer.


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