Exhaust System And Turbocharger

EXCESSIVE EXHAUST NOISE 1. Leaks at pipe joints.                  1. Tighten clamps/bolts at leaking
   OR LEAKING EXHAUST                                              joints.
          GASES          2. Rusted or blown out muffler.           2. Replace muffler. Inspect

exhaust system. 3. Broken or rusted out exhaust 3. Replace exhaust pipe. pipe.

                                 4. Exhaust pipe leaking at        4. Tighten/replace flange attaching
                                 manifold flange.                  nuts/bolts.
                                 5. Exhaust manifold cracked or    5. Replace exhaust manifold.

broken. 6. Leak between exhaust manifold 6. Tighten exhaust manifold to and cylinder head. cylinder head bolts. Replace gasket if necessary. 7. Turbocharger mounting flange 7. Remove turbocharger and cracked. inspect. (Refer to REMOVAL . 8. Restriction in exhaust system. 8. Remove restriction, if possible. Replace restricted part if necessary.

                                 9. EGR pipe(s) leak.              9. Tighten bolts. Replace gasket.
                                 10. EGR assembly leak.            10. Tighten bolts. Replace gaskets.
  Driveability Concern - Turbo   1. Vacuum hose disconnected.      1. Check connections, replace as

necessary. 2. Vacuum system leaks. 2. Inspect for damage. Check for leaks, replace as necessary. 3. Boost pressure solenoid filter 3. Replace the filter. clogged.

EXCESSIVE EXHAUST NOISE 1. Leaks at pipe joints.                   1. Tighten clamps/bolts to
OR LEAKING EXHAUST                                                 specified torque at leaking joints.
GASES                   2. Rusted or blown out muffler.            2. Replace muffler. Inspect

exhaust system. 3. Broken or rusted out exhaust 3. Replace exhaust pipe. pipe. 4. Exhaust pipe leaking at 4. Tighten/replace flange attaching

                                manifold flange.                  nuts/bolts.
                                5. Exhaust manifold cracked or    5. Replace exhaust manifold.

broken. 6. Leak between exhaust manifold 6. Tighten exhaust manifold to

                                and cylinder head.                cylinder head bolts.
                                7. Catalytic converter rusted or  7. Replace catalytic converter
                                blown out.                        assy.

8. Restriction in exhaust system. 8. Remove restriction, if possible. Replace restricted part if necessary.

When servicing and replacing exhaust system components, disconnect the oxygen sensor connector(s). Allowing the exhaust to hang by the oxygen sensor wires will damage the harness and/or sensor.

Flange-to-Exhaust Manifold Bolts Front Exhaust pipe-to- 36 28 - Muffler Flange Nuts Turbocharger Support 24 18 - Bracket Bolts Turbocharger Downpipe 32 24 - Nuts Turbocharger Oil Supply 24 18 215 Line Fitting Turbocharger Oil Return 11 - 96 Line bolts Turbocharger to Exhaust 32 24 - Manifold Nuts

A diesel particulate filter DPF is installed for exhaust gas after-treatment. The DPF is located downstream of the main oxidation catalyst. The DPF filters, stores and burns particulate matter (soot) that is generated during the combustion process. The soot is oxidized to carbon dioxide CO2 at exhaust temperatures over 600° C (1,112° F).

The oxidation catalysts raise the exhaust gas temperatures to regenerate the DPF , which is passive regeneration. If the passive regeneration cannot keep up with the build up of soot in the DPF, the ECM will actively regenerate the DPF to burn off the soot. Residue remains inside the DPF in the form of non burnable ash. Ash comes from the oils and other materials that are trapped in the oils and are present in the soot. Ash is not eliminated by the regeneration cycle. Excessive ash accumulation requires the replacement of the DPF. The DPF uses a silicon carbide wall-flow monolith with a platinum coating to trap particulates. The monolith contains a large number of square parallel channels, which run in the axial direction and are separated by thin porous walls. The channels are alternatively open at one end, but plugged at the other. The exhaust gases flow through the walls and escape through the pores in the wall material. Particulates, however, are too large to escape and are trapped in the monolith walls. The ECM starts the regeneration of the DPF if the soot load exceeds a performance map value. The ECM determines the load condition of the DPF based upon the exhaust gas pressure upstream and downstream of the DPF. A pressure differential sensor provides the pressure input to the ECM. During the regeneration process, the ECM raises the temperature in the DPF to burn off the soot accumulated. Under normal operation, the engine does not produce enough heat to oxidize the soot inside the DPF. This process requires temperatures above 550 °C (1,022 °F). After regeneration, the ECM reads the actual pressure difference at the DPF and compares it with a reference value. From this comparison, the ECM determines the ash quantity inside the DPF.

1 - MANIVERTER 2 - MANIVERTER TO DFP FLANGE 3 - PRESSURE SENSOR TUBING

4 - STEADY MOUNT 5 - FLEXIBLE BELLOWS 6 - ISOLATOR 7 - MUFFLER/TAIL PIPE ASSEMBLY 8 - DPF TO MUFFLER FLANGE

1 - MANIVERTER 2 - MANIVERTER TO DFP FLANGE 3 - PRESSURE SENSOR TUBING 4 - STEADY MOUNT 5 - FLEXIBLE BELLOWS 6 - ISOLATOR

7 - MUFFLER/TAIL PIPE ASSEMBLY 8 - DPF TO MUFFLER FLANGE

1 - TURBINE SECTION 2 - EXHAUST GAS 3 - BEARING HOUSING 4 - COMPRESSOR SECTION 5 - INLET AIR 6 - COMPRESSED AIR TO ENGINE 7 - EXHAUST GAS 8 - EXHAUST GAS TO EXHAUST PIPE

CAUTION: The turbocharger is a performance part and must not be tampered with. The wastegate bracket is an integral part of the turbocharger. Tampering with the wastegate components can reduce durability by increasing cylinder pressure and thermal loading due to incorrect inlet and exhaust manifold pressure. Poor fuel economy and failure to meet regulatory

emissions laws may result. Increasing the turbocharger boost WILL NOT increase engine power.

The turbocharger is an exhaust-driven supercharger which increases the pressure and density of the air entering the engine through the charge air cooler. With the increase of air entering the engine, more fuel can be injected into the cylinders, which creates more power during combustion.

The turbocharger assembly consists of four (5) major component systems. See Fig. 15.

Turbine section Compressor section Bearing housing Variable veins Actuator

1 - BEARINGS 2 - OIL SUPPLY (FROM ENGINE BLOCK) 3 - OIL RETURN (TO OIL PAN)

Exhaust gas pressure and energy drive the turbine, which in turn drives a centrifugal compressor that compresses the inlet air, and forces the air into the engine through the charge air cooler and plumbing. Since heat is a by-product of this compression, the air must pass through a charge air cooler to cool the incoming air and maintain power and efficiency.

Increasing air flow to the engine provides:

Improved engine performance

Lower exhaust smoke density Improved operating economy Altitude compensation Noise reduction.

The turbocharger is lubricated by engine oil that is pressurized, cooled, and filtered. The oil is delivered to the turbocharger by a supply line (2) that is tapped into the engine block. The oil travels into the bearing housing, where it lubricates the shaft (1) and bearings. See Fig. 16. A return pipe (3) at the bottom of the bearing housing, routes the engine oil back to the crankcase.

The most common turbocharger failure is bearing failure related to repeated hot shutdowns with inadequate "cool-down" periods. A sudden engine shut down after prolonged operation will result in the transfer of heat from the turbine section of the turbocharger to the bearing housing. This causes the oil to overheat and break down, which causes bearing and shaft damage the next time the vehicle is started.

Letting the engine idle after extended operation allows the turbine housing to cool to normal operating temperature. The following chart should be used as a guide in determining the amount of engine idle time required to sufficiently cool down the turbocharger before shut down, depending upon the type of driving and the amount of cargo.

Low turbocharger boost pressure can cause poor engine performance and driveability concerns. The following procedure will test the turbocharger boost pressure.

Causes of low boost pressure include the following:

Restricted air inlet system Leak in charge air cooler system Restricted/high pressure drop across charge air cooler Damaged turbocharger compressor wheel housing Turbocharger wastegate stuck open

Excessive exhaust restriction

Causes of excessively high boost pressure include:

Turbocharger wastegate stuck closed Turbocharger wastegate signal line leaking or damaged Damaged wastegate command valve O-rings Wastegate command valve mechanically stuck in actuated position

Several Diagnostic Trouble Codes (DTCs) can be set that will indicate high or low system boost levels. There is a DTC for circuit faults relating to the electronically controlled wastegate command valve.

See DIAGNOSIS AND TESTING for diagnosing of low or high boost pressure due to leaks.

1 - EGR VALVE MOUNTING STUDS

2 - EXHAUST MANIFOLD 3 - TURBOCHARGER TO EXHAUST MANIFOLD MOUNTING STUDS 4 - TURBOCHARGER ASSEMBLY 5 - TURBOCHARGER OIL RETURN FITTING ATTACHING BOLT 6 - TURBOCHARGER OIL RETURN FITTING 7 - OIL RETURN FITTING GASKET 8 - RETAINING NUT 9 - TURBOCHARGER TO EXHAUST MANIFOLD GASKET

All old gaskets should be inspected for any tears or signs of prior leakage. If any gaskets show such indications, they should be replaced with new gaskets. All gasket mating surfaces must be cleaned of old gasket material to produce a smooth and dirt free sealing surface for the new gasket.

1 - CLAMP 2 - TURBOCHARGER 3 - AIR DUCT RUBBER SLEEVE 4 - AIR INLET DUCT

Low turbocharger boost pressure and low engine performance can be caused by leaks in the charge air cooler or plumbing. Fuel staining on the exhaust manifold can also be an indication that there are leaks in the air system. The following procedure outlines how to check for leaks in the charge air cooler system.

This procedure can also be used to check for leaks in the wastegate signal line or the wastegate canister.

1. Loosen clamp (1) and remove air inlet hose (3) from turbocharger. 2. Insert Special Tool 9022 Adapter into the turbocharger inlet. Tighten tool clamp to 8 N.m (72 in. lbs.).

CAUTION: Do not apply more than 138 kPa (20 psi) air pressure to the charge air cooler system; severe damage to the charge air cooler system may occur.

3. Connect a regulated air supply to air fitting on Tool 9022 Adapter. Set air pressure to a maximum of 138 kPa (20 psi). 4. Using soapy water check the rubber sleeves, charge air cooler and intake manifold for leaks. 5. Using soapy water check for leaks at the wastegate signal line, wastegate canister and wastegate command valve.

1 - CHARGE AIR COOLER 2 - HOSE CLAMP 3 - CHARGE AIR COOLER INLET HOSE 4 - HOSE CLAMP

1. Open and support hood of vehicle. 2. Loosen hose clamps at both ends of charge air cooler (CAC) inlet hose. See Fig. 19. 3. Remove CAC inlet hose (3) from turbocharger and CAC.

1 - CHARGE AIR COOLER 2 - HOSE CLAMP

3 - INTAKE MANIFOLD INLET 4 - HOSE CLAMP 5 - CHARGE AIR COOLER OUTLET HOSE

1. Raise and support hood on vehicle. 2. Loosen hose clamps at both ends of charge air cooler (CAC) outlet hose (5). See Fig. 20. 3. Remove hose (5) from CAC and intake manifold inlet. See Fig. 20.

1. Install charge air cooler (CAC) inlet hose on turbocharger and CAC. 2. Tighten hose clamps. 3. Close hood.

1. Install charge air cooler (CAC) outlet hose on CAC and intake manifold inlet. 2. Tighten both hose clamp on CAC outlet hose. 3. Close hood.