Exhaust System
Exhaust System
The 6.4L diesel exhaust system consists of the following:
- Turbocharger inlet pipes (located on the backside of the engine)
- EGR-Oxidation Catalytic Converter (OC) pipe (located on the backside of the engine)
- Downpipe (located on the backside of the engine)
- OC (located on the RH frame rail)
- Diesel Particulate Filter (DPF) (located on the RH frame rail)
- Intermediate pipe (if equipped)
- Tail pipe with a built-in resonator
The gasoline exhaust system consists of the following:
- Exhaust Y-pipe
- Catalytic converter (if equipped) (located on the RH frame rail)
- Catalytic converter delete pipe (if equipped) (located on the RH frame rail)
- Intermediate pipe (if equipped)
- Muffler and tail pipe assembly
Exhaust System
The exhaust system provides an exit for exhaust gases and reduces engine noise by passing exhaust gases through the catalytic converter and a muffler assembly. Rubber exhaust hanger isolators attach the exhaust system to the mounting hooks.
Turbocharger Inlet Pipe - 6.4L Diesel
The turbocharger inlet pipes transport the exhaust gas from the exhaust manifolds to the turbocharger. The expansion joint in the turbocharger inlet pipes is to accommodate thermal growth in the turbocharger inlet pipes and is not an assembly aid. The turbocharger inlet pipes should not be bent or twisted at the expansion joint.
EGR-OC - 6.4L Diesel
The EGR-OC pipe transports exhaust gases to the EGR coolers. The EGR-OC pipe contains a honeycomb filter with a catalyst. The catalyst keeps the EGR coolers clean by removing heavy chain hydrocarbons or soluble organic fraction from the exhaust gas stream.
The bracket from the EGR-OC pipe to the cylinder head is critical for durability of the horizontal EGR cooler. This bracket must be correctly assembled with bolts to prevent damage to the EGR cooler.
Catalytic Converter - Gasoline Engines
The catalytic converter plays a major role in the emission control system. The catalytic converter operates as a gas reactor. Its catalytic function is to speed the heat-producing chemical reaction of components in the exhaust gases in order to reduce air pollutants. The catalyst material inside the catalytic converter consists of a ceramic substrate.
The catalytic converter is designed to provide a long life. No maintenance is necessary for the catalytic converter.
Oxidation Catalytic Converter (OC) and Diesel Particulate Filter (DPF) - 6.4L Diesel
The OC is coupled to a DPF which reduces the amount of air pollutants in the exhaust emitted from the tailpipe. The OC is a ceramic catalytic converter which oxidizes hydrocarbons in the exhaust and generates heat for DPF regeneration. The DPF is a highly engineered silicon carbide wall-flow catalyst that traps particulates. As soot gathers in the system it begins to restrict the filter and the filter needs to be periodically cleaned. The soot can be cleaned in 2 different ways: Passive regeneration and active regeneration. Both methods occur automatically and require no action from the driver/operator.
Over time a slight amount of ash will build up in the DPF which is not removed during the regeneration process. The DPF will need to be removed for ash cleaning at approximately 193,000 km (120,000 mi) or greater (actual mileage can vary greatly depending upon engine/vehicle operating conditions) and replaced with a new or remanufactured (ash cleaned) part. A new DPF will need to be installed at approximately 400,000 km (250,000 mi) or greater depending on engine/vehicle operating conditions. In both cases the PCM will set a check engine light to inform the customer to bring the vehicle to the dealer for service. If there are any issues with the OC/DPF system, a check engine light will be set by the PCM.
Passive Regeneration - 6.4L Diesel
Passive regeneration occurs naturally as a result of normal engine operating conditions. During passive regeneration, the exhaust constituents/temperature are at an appropriate level where some soot can be reduced or oxidized (burned) thus cleaning the filter.
Active Regeneration - 6.4L Diesel
Active regeneration, which is initiated by the PCM, will occur when there is not enough passive regeneration occurring due to vehicle drive patterns. In an active regeneration, the DPF is cleaned by raising the exhaust temperature to a point where the soot is burned away. After the soot is burned off, the exhaust temperature and back pressure (restriction) fall back to normal levels.
Sound Insulators and Shields
Sound insulators and shields attached to the underbody protect the vehicle from exhaust system heat and should be inspected at regular intervals to make sure they are not dented or out of position. If a sound insulator and shield is damaged or shows evidence of deterioration, a new sound insulator and shield should be installed. The sound insulators and shields for the muffler, exhaust downpipe, inlet pipe and catalytic converter pipe are installed separately.
Precautions
WARNING: Keep the holes and tabs in the tailpipe free of foreign material or blockage. Do not modify or permanently remove the tailpipe section that contains the holes. Operating the vehicle with plugged or blocked holes or with modifications to the system may result in elevated exhaust gas temperatures, which may burn persons contacted by the exhaust gas. Failure to follow these instructions may result in serious personal injury to the technician or vehicle occupant(s).
WARNING: Initiate a manual regeneration of the diesel particulate filter (DPF) only when the vehicle is on the ground with the area around the tailpipe free of people, obstructions, foreign material or other items. Manual regeneration causes the exhaust gas to quickly get VERY HOT. Failure to follow these instructions may result in serious personal injury.
NOTICE: Do not use leaded fuel in a vehicle equipped with a catalytic converter. In a vehicle that is continually misfueled, the lead in the fuel will be deposited in the catalytic converter and completely blanket the catalyst. Lead reacts with platinum to "poison" the catalyst. Continuous use of leaded fuel can destroy the catalyst and render the catalytic converter useless.
NOTICE: The addition of lead to the catalytic converter can also solidify the catalyst, causing excessive back pressure in the exhaust system and possibly causing engine damage.
NOTICE: For areas where ultra low sulfur diesel fuel (15 ppm sulfur maximum) is required, use only ultra low sulfur diesel fuel in diesel vehicles equipped with an Oxidation Catalytic Converter (OC) and Diesel Particulate Filter (DPF). In a diesel vehicle that is continually misfueled by using low sulfur (16-500 ppm) or high sulfur (500 ppm or greater) diesel fuel, the sulfur can effectively poison the catalyst. Continuous use of low sulfur or high sulfur can destroy the catalyst and render the catalyst useless.
NOTICE: Extremely high temperatures (1,100°C [2,012°F] or above) due to misfiring or over-rich fuel/air mixture will cause the ceramic substrate or Diesel Particulate Filter (DPF) substrate to sinter or burn, destroying the catalytic converter, Oxidation Catalytic Converter (OC) and/or DPF. Do not continue to operate the vehicle if the engine is misfiring, there is a power loss or other unusual operating conditions, such as engine overheating and backfiring.
NOTICE: Do not use oil or grease-based lubricants on the isolators. These lubricants may cause deterioration of the isolator. This can lead to separation of the isolator from the exhaust hanger bracket during vehicle operation.
NOTE: Exhaust fasteners are of a prevailing torque design. Use only new fasteners with the same part number as the original. Torque values must be used as specified during reassembly to make sure of correct retention of exhaust components.
Make sure to follow these precautions when carrying out the procedures.