
2011-2015 Chevy/GMC 6.6L Duramax LML Turbo Diesel 3Inch Downpipe Exhaust
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Step 1 :
First, remove the passenger-side inner fender to provide sufficient operating space. It is also recommended to remove the grille assembly to prevent damage during downpipe removal or installation.
Step 2:
Remove the hex bolts securing the downpipe to the exhaust manifold. Then remove the sensor located directly above the hex bolts. The V-clamp connecting the front pipe and downpipe can also be removed. Keep the removed hex bolts, sensor, and V-clamp for later installation.

Step 3:
Temporarily remove the exhaust front pipe, carefully disconnect the sensor, and loosen the four flange nuts at the rear of the front pipe. The transmission crossbeam needs to be temporarily lowered before removing the front pipe. Use a jack bracket to support the transmission before removing the transmission crossbeam. The exhaust front pipe also has a hanger mounted on the transmission, which also needs to be removed.
Step 4:
The heat shield on top of the turbine needs to be removed. A heat shield extending along the firewall at the rear of the downpipe also needs to be removed.
Step 5:
Carefully remove the two original sensors at the top of the downpipe, and also remove the original V-clamp. Keep both safe for future installation. This allows you to carefully slide the original downpipe out from between the chassis and transmission from under the vehicle or the passenger-side wheel arch.

Step 6:
Begin installation now. First, insert the downpipe upwards from the bottom of the vehicle or the passenger side wheel arch. Align the flange with the turbocharger and install the V-clamp at the turbocharger. Do not tighten the clamp too much yet, leave some room for rotation.

Step 7:
Loosely secure the downpipe to the exhaust manifold using the hex bolts on the original downpipe. Tighten the V-clamp at the turbocharger, then tighten the bolts on the exhaust manifold.
Step 8:
Install the original sensors onto the downpipe. One sensor is located at the bottom of the downpipe. The other two sensors are near the turbocharger.

Step 9:
The front exhaust pipe can then be reinstalled using the original hardware and V-clamps.
Step 10:
Reinstall the exhaust pipe hanger onto the transmission crossbeam. Reinstall the transmission crossbeam. Reconnect all sensors to the front exhaust pipe.
Step 11:
Reinstall the turbocharger heat shield. Inspect the exhaust pipe, ensuring all connections are tightened. Inspect the entire exhaust system, ensuring sufficient clearance around the spare tire, fuel lines, brake lines, or any wiring. If any obstructions are found, reposition or adjust them.
After inspection, reinstall the passenger-side inner fender.






