Service BulletinMack Trucks, Inc.Greensboro, NC USA Trucks

Date Group No. Release Page

11.2009 214 32 01 1(21)

Rocker Arms

Replacement (All)

MP8

Rocker Arms, Replacement (All)

W2006240

This information covers the service procedures for replacing the rocker arms and shaft onMP8 engines.

Contents• “Special Tools”, page 2

• “Rocker Arms, Replacement (All)”, page 3

Note: Information is subject to change without notice.Illustrations are used for reference only and may differ slightly from the actual engineversion. However, key components addressed in this information are represented asaccurately as possible.

PV776-88945215 USA38627

Mack Trucks, Inc. Date Group No. Release PageService Bulletin 11.2009 214 32 01 2(21)

ToolsSpecial Tools

The following special tools are used to replace or repair components. Please refer to thespecified part number when ordering.

T0012612

88800014Flywheel Turning Tool

85109250Rocker Assembly Lifting Tool

Mack Trucks, Inc. Date Group No. Release PageService Bulletin 11.2009 214 32 01 3(21)

Service Procedures2145-03-04-01

Rocker Arms, Replacement (All)

You must read and understand the precautions andguidelines in Service Information, group 20, "GeneralSafety Practices, Engine" before performing anyprocedure. If you are not properly trained and certifiedin this procedure, ask your supervisor for training beforeyou perform it.

Special tools: 85109250, 88800014

Removal1

1Apply the parking brake and place the shift lever inneutral.

22Remove all cables from ground (negative) batteryterminals to prevent personal injury from electrical shock.

33Disconnect and remove the air cleaner differentialpressure gauge wiring harness from the air cleanerhousing.

4

W2004720

4Disconnect the intake air temperature sensor wiringharness connector (if equipped) by cutting the tie strap,removing the lock tab and separating the connector fromthe sensor. Also, remove the clamp securing the sensorharness to the intake air pipe.

Mack Trucks, Inc. Date Group No. Release PageService Bulletin 11.2009 214 32 01 4(21)

5

W2004719

5Loosen the air compressor intake air hose clamp at themain intake air pipe. Separate the hose from the pipe.

6

W2006005

6Loosen the clamps and remove the main intake air pipefrom the air cleaner housing and turbocharger air inletelbow.

77Remove the fasteners and lift the air cleaner housingaway from the cab.

Mack Trucks, Inc. Date Group No. Release PageService Bulletin 11.2009 214 32 01 5(21)

8

W2030311

1 Venturi Outlet Pipe

2 Crossover Pipe

3 Mixer Inlet Pipe

8Loosen the V-clamps and remove the EGR crossoverpipe.

Note: US07 configuration shown.

99Loosen the coupling hose clamp and loosen the clampbrackets that secure the air compressor intake air pipe;remove the pipe from the engine.

1010Remove the aftertreatment doser harness from the clipsat the valve cover.

11

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11Remove the fasteners which secure the crankcasebreather tube and bracket to the valve cover and intakemanifold. Relocate the tube away from the manifold.

Mack Trucks, Inc. Date Group No. Release PageService Bulletin 11.2009 214 32 01 6(21)

1212Disconnect the discharge line and mounting bracketsfrom the air compressor. Move the discharge air line outof the way and strap it in place.

13

T2022732

13Remove the spring-loaded bolts from the valve cover.

1414Lift and remove the valve cover.

Note: Rotate the valve cover as needed, to clear thecamshaft gear and damper.

Note: Dependent upon chassis, engine cover may needto be removed for clearance to remove valve cover.

15

W0002368

15Remove the plug from the flywheel housing and installthe flywheel turning tool.

88800014

Mack Trucks, Inc. Date Group No. Release PageService Bulletin 11.2009 214 32 01 7(21)

16

W2006173

16Using the engine turning tool, turn the engine overmanually so that the camshaft is positioned at top deadcenter (TDC) by aligning the TDC mark on the camshaftwith the timing marks on the No. 1 camshaft bearing cap.Make sure flywheel is on 0 degrees mark.

88800014

17

W2005845

17On engines equipped with an engine brake, using anAllen wrench, remove all mounting fasteners for the leafsprings on the brake rockers. Remove the leaf springs.

Mack Trucks, Inc. Date Group No. Release PageService Bulletin 11.2009 214 32 01 8(21)

18

W2006172

18On engines equipped with an engine brake, secure thepistons in the exhaust rocker arms using rubber bands(or tie straps) to prevent piston damage.

Note: Pistons and rocker arms are matched togetherand should not be mixed.

1919If equipped on the engine, disconnect the fuel injectorharness from the engine brake control valve by cuttingthe tie straps.

20

W2004837

20If equipped on the engine, disconnect the engine brakecontrol valve harness.

Mack Trucks, Inc. Date Group No. Release PageService Bulletin 11.2009 214 32 01 9(21)

21

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21Remove the engine brake control valve (if equipped),along with the pipe between the valve and rocker armshaft.

Note: On engines without the engine brake, an oil flowadapter is used in place of the oil control valve. It ismounted in the same location on the cylinder head andprovides oil to the rocker shaft.

2222Beginning at the center camshaft bearing cap, beginloosening the fasteners at each bearing cap evenly instages until all fasteners are completely loose. Onceloosened, remove the fasteners.

CAUTION

The order of the rocker arm assembly must bemaintained. Make certain the sets of four are kepttogether. Make certain the rocker arms are identifiedso they can be returned to their original positions onthe shaft. Failure to heed this caution may result insevere engine damage.

2323Attach the lifting tool to the rocker arm shaft.

85109250

24

W2005513

1 Lifting Tool 85109250

2 Rocker Shaft Assembly

24With the aid of an assistant, carefully lift off the shaftassembly using the lifting tool. Place the rocker shaft insecure location.

Note: On engines equipped with engine brake, ensurethe pistons are secured in the exhaust rocker arms withelastic bands so that the pistons do not fall out as theshaft is removed.

85109250

Mack Trucks, Inc. Date Group No. Release PageService Bulletin 11.2009 214 32 01 10(21)

25

W2005514

1 Camshaft Bearing Cap

2 Camshaft

3 Alignment Sleeve

25With the rocker shaft assembly removed, check to ensurethat the alignment sleeves remain in position on eachbearing cap.

Mack Trucks, Inc. Date Group No. Release PageService Bulletin 11.2009 214 32 01 11(21)

Disassembly, Inspection and Reassembly

The following components can be replaced: rockerarm shaft, expansion plugs, complete rocker arms andadjusting screws.

11Place the rocker shaft assembly on a workbench andremove the lifting tool.

22Mark the rocker arms so they can be reinstalled in theiroriginal locations.

3

W2006231

3Remove the rocker arms from the rocker arm shaft.

44Clean the parts, paying special attention to the oilchannels in the bearing housing and the oil holes for therocker arm shaft and rocker arms.

55Inspect all components of the rocker arm assembly fordamage and excessive wear. If the roller does not moveor binds, replace the rocker arm.

66Check the valve and piston action on the exhaust rockerarms for any signs of binding. Replace as necessary.

Mack Trucks, Inc. Date Group No. Release PageService Bulletin 11.2009 214 32 01 12(21)

77Check the wear on the rocker arm shaft and ball screws.The threads should be undamaged on ball screws andlocknuts.

Note: If a rocker arm has an overly worn bushing, replacethe complete rocker arm.

88Arrange the rocker arms in sets according to the markingsmade at disassembly.

9

W2005940

9Lubricate the rocker arm shaft, rocker arm bore, and oilfeed hole in the rocker arm that feeds oil to the roller/axialpin. Turn the rocker roller while injecting clean engine oilto ensure the roller/axial pin is lubricated properly.

Note: It is extremely important that the rocker arms androcker arm shaft are carefully cleaned and oiled withengine oil before rocker arms and shafts are installedtogether.

10

W2006240

10Install all the rocker arm sets on the rocker shaftaccording to the markings made at disassembly. Checkthat they move freely.

1111With the rocker arms in place on the shaft, carefullyattach the lifting tool to the rocker shaft assembly.

Mack Trucks, Inc. Date Group No. Release PageService Bulletin 11.2009 214 32 01 13(21)

Installation1

1Oil the valve bridges and the camshaft lobes with engineoil.

2

W2005513

1 Lifting Tool 85109250

2 Rocker Shaft Assembly

2Using the lifting tool and an assistant, place the rockershaft assembly in position on the inboard side of thecamshaft bearing caps.

33Remove the lifting tool. Then, install and tighten therocker arm shaft bolts a little at a time, evenly across theentire shaft so that the shaft does not become distorted,bent or fractured.

Note: Make sure that the rocker arm shaft is seatedproperly in the guide dowels of the camshaft bearingcaps. On engines equipped with the engine brake,remove the restraints (rubber bands or tie straps)securing the exhaust rocker arm pistons.

85109250

44Lubricate the rocker arm rollers.

Mack Trucks, Inc. Date Group No. Release PageService Bulletin 11.2009 214 32 01 14(21)

5

W2005481

5Torque-tighten and angle tighten to specificationsall camshaft bearing cap and rocker arm shaft boltsaccording to the sequence shown in the specifications.

Note: Tighten the bolts in the step sequence shown inthe specifications to ensure that the rocker arm shaft isfully seated without bending.

Note: The bolts have limited reusability and must bemarked (A) with a punch each time they are installed inservice. Bolts with four punch marks when removed havebeen tightened five times and must be discarded.

6

W2004855

6Replace the O-ring at the bottom of the engine brakecontrol valve (if equipped with engine brake) or oil flowadapter.

Note: On engines without the engine brake, an oil flowadapter is used in place of the oil control valve. It ismounted in the same location on the cylinder head and isinstalled in the same manner as the engine brake controlvalve in steps 7 through 11. The adapter provides oil tothe rocker shaft.

7

W2004853

7Clean the engine brake control valve oil pipe and replacethe O-rings. Lubricate the pipe hole in the rocker armshaft and the O-rings on the pipe.

Mack Trucks, Inc. Date Group No. Release PageService Bulletin 11.2009 214 32 01 15(21)

8

W2004854

8Insert the oil pipe into the oil hole of the engine brakecontrol valve.

Note: Make sure that the O-ring is seated fully in thevalve.

9

W2004869

9Position the engine brake control valve on the cylinderhead.

10

W2004857

10Align the engine brake oil pipe and O-ring with the hole inthe rocker shaft.

Mack Trucks, Inc. Date Group No. Release PageService Bulletin 11.2009 214 32 01 16(21)

11

W2004858

11Install the engine brake control valve bolts and tightento specification.

Note: Make sure the engine brake oil pipe O-ring is fullyseated.

12

W2004837

12Plug-in the engine brake control valve harness connector.

1313Reposition the fuel injector harness over the enginebrake control valve and secure with tie straps.

14

W2006173

14When adjusting the valves, make sure to start with thecamshaft cylinder alignment marks between the two lineson the front camshaft.

Mack Trucks, Inc. Date Group No. Release PageService Bulletin 11.2009 214 32 01 17(21)

1515Adjust the valves and unit injectors to specification. Referto the adjustment procedure in Group 21.

16

W2005845

16Place the leaf springs (if equipped with engine brake)in position on the camshaft bearing caps. Install thefasteners and tighten to specification.

17

W0002368

17Remove flywheel turning tool 88800014. Reinstall thedust plug.

88800014

1818Clean and inspect the valve cover seal and sealingsurface on the cylinder head. The surfaces should beclear of any dirt or debris and free of any oil.

1919Inspect the gasket for damage. If replacement isnecessary, carefully place a new gasket into the channel,making sure it is properly seated and follows the contourof the channel.

Mack Trucks, Inc. Date Group No. Release PageService Bulletin 11.2009 214 32 01 18(21)

20

W2005157

20Apply a 2 mm (0.079 inch) bead of sealant to the areawhere the timing cover and the cylinder head meet.This parting line is on both sides of the cylinder head.Carefully position the valve cover on the cylinder headand make sure that the seal remains properly seated.

Note: This step is very critical to ensure no oil leaksoccur.

Note: The cylinder head cover must be installed within20 minutes of the sealant being applied.

21

T2022732

21Install the spring-loaded bolts in the valve cover.Torque-tighten the valve cover bolts to specification inthe sequence shown.

Note: Install the engine cover, if removed for clearance.

Note: The bolt springs provide even tension on the valvecover gasket.

2222Connect the discharge line and mounting brackets for themain air line to the air compressor.

2323Install the aftertreatment doser harness to the clips inthe valve cover.

2424Inspect the EGR crossover pipe V-clamps for wear ordamage; replace as necessary. Lubricate the clampscrew threads and the “V” inserts of the clamp.

2525Place the V-clamps and EGR crossover pipe (with newO-rings) in position between the venturi outlet pipe andthe mixer inlet pipe.

Mack Trucks, Inc. Date Group No. Release PageService Bulletin 11.2009 214 32 01 19(21)

26

W2005804

26Install a V-clamp at each end of the EGR crossover pipeand tighten the clamps to secure the pipe.

Note: Make sure the O-rings remain in place whilepositioning the pipe.

2727Install the air compressor intake air pipe by tighteningthe coupling hose clamp and securing the pipe clampbrackets on the engine.

28

W2030312

28Install the fasteners securing the crankcase breathertube and bracket to the valve cover and intake manifold.Tighten fasteners to specification.

Note: Inspect the crankcase breather tube O-ring andreplace if necessary.

Note: Ensure that the same bolts that were removedat disassembly are reinstalled in the same location.Damage to the valve cover will result if bolts that are toolong are installed.

2929Position the air cleaner housing against the cab andinstall fasteners to secure.

Mack Trucks, Inc. Date Group No. Release PageService Bulletin 11.2009 214 32 01 20(21)

30

W2006005

30Install the main intake air pipe between the air cleanerhousing and the turbocharger air inlet elbow. Position theclamps and tighten to secure.

31

W2004719

31Install the air compressor intake air hose to the mainintake air pipe, position the clamp and tighten to secure.

32

W2004720

32Install the intake air temperature wiring harnessconnector (if equipped) to the sensor. Insert and securethe connector lock tab with a tie strap. Install the sensorharness clamp to the main intake air pipe to secure theharness. Tighten the clamp screw to specification.

Mack Trucks, Inc. Date Group No. Release PageService Bulletin 11.2009 214 32 01 21(21)

3333Connect and secure the air cleaner differential pressuregauge wiring harness to air cleaner housing.

3434Install all previously removed cables to the ground(negative) battery terminals.

3535Start the engine, check for leaks and proper operation.