The exhaust manifold transports the extremely hot gases produced in the engine's cylinders to their next destination. In the case of trucks equipped with a Cummins diesel motor, these fiery exhaust gasses are routed through the turbocharger and out of the system through the vehicle's exhaust pipe. If a Cummins-equipped truck is suffering from an exhaust leak at the manifold, but the manifold itself is in proper operating condition, the cause of the leak is often a faulty gasket.
Park your vehicle on a flat surface. Raise the hood and prop it open. Allow the engine to cool completely. Disconnect the turbo and any additional items, such as exhaust gas temperature sensors, that may be connected to the exhaust manifold. Do not remove the turbo itself; simply disconnect it from the manifold. Remove the manifold heat shield by loosening the four bolts holding it in place.
Remove the bolts that secure the exhaust manifold to the engine head, using a 13 mm deep socket. Store the bolts in a safe location, as you will need them for reinstallation of the manifold.
Clean the exposed surfaces on the head of the motor, turbo and exhaust manifold using a clean, lint-free rag. Installing the new gasket onto a clean surface will help ensure a tight seal and reduce the risk of exhaust leaks.
Coat all of the bolt holes where the exhaust manifold attaches to the engine, using an anti-seize product. Repeat this process on the mounting holes for the turbo on the exhaust manifold. The application of anti-seize will help ensure that the bolts are manageable during any future repair work.
Line up the new exhaust manifold gasket on the exhaust manifold itself. Slip the exhaust manifold and gasket into position against the engine and replace the 12 manifold mounting bolts. Secure the manifold in place and reconnect the turbo to the manifold gasket. Secure the heat shield and any additional sensor components that you removed during the course of the gasket installation.
Torque the exhaust manifold bolts to the specifications listed in the owner's manual. Test drive the vehicle and check to see that the initial issue has been remedied by listening and visually inspecting for exhaust leaks at the manifold gasket.
