The TDV8 exhaust system is fabricated from stainless steel and is supplied as three separate assemblies; a left-hand (LH) front section incorporating a catalytic converter, a right-hand (RH) front section incorporating a catalytic converter and a rear section incorporating a centre silencer and two rear silencers. In service sections of the system can be replaced individually. Service joints are identified by indentations on the pipes which show where the exhaust pipes can be cut to accommodate replacement sections.
After the replacement sections are positioned, the system integrity is restored by sealing the service joints with one piece sleeves and two clamps to connect the pipes at the cut points.
The system is attached to the underside of the body with four rubber mountings which are located on mild steel hanger bars that are welded to the system. The rubber mountings locate on adjacent hanger brackets which are bolted to the underside of the vehicle body.
On vehicles from 2008MY, an optional Diesel Particulate Filter (DPF) is available. The non-DPF exhaust system is also available on vehicles from 2008MY as the DPF is not required to comply with EU4 emission regulations.
The use of bio-fuels can seriously contaminate and destroy the coatings used on the catalytic converter. The DPF and the catalytic converter can become irreversibly contaminated if non-specified oils or fuels are used. This will result in the vehicle being unable to regenerate the DPF, becoming non-compliant with tailpipe emission regulations and replacement of the catalytic converter and DPF will be required.
If the vehicle is waded in deep water and the engine is stopped with the tailpipes submerged, the water, which can enter the system, can also contaminate both the DPF and the catalytic converter. This again can result in catalytic converter damage and damaging the ability for the DPF to regenerate therefore requiring both components to be replaced.
The front down pipes have a welded flange with three holes which provide for the attachment to the turbocharger using three bolts. The flange is sealed with a metal gasket.
The flange is welded to a fabricated elbow which feeds into a decoupler which in turn is connected to the 2.2 liter (134 in3) catalytic converter.
On the LH front section, the converter outlet pipe is welded to the converter body. The rear of the outlet pipe is inserted into the flared end of the rear section. A clamp is used to compress and secure the joint.
On the RH front section, the converter outlet pipe is welded to the converter body. The rear of the pipe curves left, under the transmission and then curves again to run parallel to the LH pipe. The end of the pipe has a welded flange with two holes which locate on two studs on the rear section and is secured with nuts. A metal gasket is used to seal the joint between the front and rear section flanges.
On the LH front section, the converter outlet pipe is welded to the converter body. The rear of the outlet pipe is inserted into the flared end of the DPF. A clamp is used to compress and secure the joint.
On the RH front section, the converter outlet pipe is welded to the converter body. The rear of the pipe curves left, under the transmission and then curves again to run parallel to the LH pipe. The end of the pipe has a welded flange with two holes which locate on two studs on the DPF and is secured with nuts. A metal gasket is used to seal the joint between the front and rear section flanges.
The rear section has a short tube welded to the front silencer assembly which is flared to locate the LH front section. A second short tube, also welded to the front silencer assembly, has a welded flange with captive studs to provide attachment for the flange on the RH front section.
The rear section has a short tube welded to the DPF which is flared to locate the LH front section. A second short tube, also welded to the DPF, has a welded flange with captive studs to provide attachment for the flange on the RH front section.
The front silencer comprises rolled stainless steel casing which is clenched via a lockseam giving a capacity of 6.4 liters (391 in3). The silencer contains baffles and perforated tubes which reduce noise as the exhaust gases pass through the silencer. A hanger bar is welded to the front right hand side of the silencer and provides for the location of a mounting rubber.
The front silencer is connected to the DPF with two welded tubes. The front silencer comprises two pressed stainless steel shells which are welded together to give a capacity of 25.2 liters (1537 in3). The silencer contains baffles and perforated tubes which reduce noise as the exhaust gases pass through the silencer. A hanger bar is welded to the front right hand side of the silencer and provides for the location of a mounting rubber. The change in silencer design for 08MY with DPF was introduced to address sound quality is during regeneration under light load driving conditions.
The front silencer has two 50 mm (1.96 in) diameter outlet pipes, with a 1.5 mm (0.06 in) wall thickness, which are curved to pass around the rear suspension components. Each outlet pipe terminates in a welded joint with the rear silencers.
A hanger bar is welded to the front face of each rear silencer and provides for the location of a mounting rubber. The silencer is a circular fabrication with a baffle tube which is surrounded with glass fibre to provide further noise suppression. Each rear silencer has a capacity of 2.7 liters (164 in3).
The rear silencers each have an outlet pipe which is curved downwards to distribute exhaust gasses away from the rear of the vehicle.
The engine management system provides accurately metered quantities of fuel to the combustion chambers to ensure the most efficient use of fuel and to minimise the exhaust emissions. To further reduce the carbon monoxide and hydrocarbons content of the exhaust gasses, catalytic converters are integrated into the front sections of the exhaust system.
To further reduce the carbon monoxide and hydrocarbons content of the exhaust gases, a catalytic converter (Diesel Oxidation Catalyst) is integrated into the front pipe of the exhaust system. In the catalytic converter the exhaust gases are passed through honeycombed ceramic elements coated with a special surface treatment called 'washcoat'. The washcoat increases the surface area of the ceramic elements by a factor of approximately 7000. On top of the washcoat is a coating containing platinum on vehicles without a DPF or platinum and palladium on vehicles with a DPF, which are the active constituents for converting harmful emissions into inert by-products. The platinum and palladium adds oxygen to the carbon monoxide and the hydrocarbons in the exhaust gases, to convert them into carbon dioxide and water.