Regulación Powerleash

8/13/2019 Regulacin Powerleash

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ENGINE SETUP AND ADJUSTMENTS

Fuel Injection Timing

There is no need to set injection pump-to-engine timing. Unit pump-to-engine timing is

programmed into and controlled by the EECU. However, the flywheel still has pumptiming marks to accommodate application to non-current engines.

Valve Adjustment

[213 NB]

Do not remove the EGR MASS Flow sensors from the cool tube to allow access to the

cylinder head covers (if so equipped). Remove the EGR cool tube as an assembly toaccess the cylinder head covers and upper valve train components.

LOCATING AND MARKING FLYWHEEL VALVE ADJUSTMENT MARKINGS

Some engines may be equipped with flywheels that have missing or illegible valve

adjustment markings. If this problem is encountered, a typical flywheel can be markedwhile the engine is in the chassis.

TYPICAL FLYWHEELS

On a typical flywheel, the top center (TC) markings, and the valve adjustmentmarkings, are directly in line with the clutch mounting bolt/bolt holes. To determine ifthe engine is equipped with a typical flywheel, view the flywheel through the timingaccess hole in the flywheel housing. Align the TC markings with the timing pointer. Ifthe flywheel is typical, there should be a clutch mounting bolt/bolt hole directly in line

with the TC marking. In this case, the valve adjustment markings should be in line witha clutch mounting bolt at three locations. Refer to Figure 1 -- Flywheel Marks .

Figure 1 -- Flywheel Marks

Pgina 1 de 28ENGINE SETUP AND ADJUSTMENTS

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There are 12 clutch mounting bolt holes in the flywheel, but only 8 of these holes areused to mount the clutch. Every third bolt hole, for a total of four, is not used. Theseholes are in an open area between the clutch mounting flanges. The unused holes areeasy to see through the timing access hole in the flywheel housing. The bolt holeswhere there are clutch mounting bolts are more difficult to see because the clutchmounting bolt head is somewhat rearward of the timing access opening. To aid incounting the clutch mounting bolt/bolt holes, keep in mind that there is slightly overfour inches between one bolt hole and the next. Locating the clutch mounting bolts maybe made easier by removing the bell housing inspection cover and viewing or feeling forthe bolts through the access hole.

After verifying that there is a clutch mounting bolt/bolt hole in line with the TC mark,the next step is to find the three locations where the valve adjustment marks should be.

Put a temporary mark (chalk, grease pencil, paint, etc.) at each of the three locations.Proceed as follows:

1. Beginning with the TC mark aligned with the timing pointer, rotate the engine inthe direction of normal rotation (counterclockwise, viewed from rear) to the nextclutch mounting bolt/bolt hole. Temporarily mark this location for cylinders 1 and6.

2. Continue rotating the engine in the normal direction and count the clutch mountingbolt/bolt holes as they pass the timing access opening. At the fourth mounting




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should be rotated in its normal direction of rotation to bring cylinder No. 1 up on thecompression stroke and TDC (inlet and exhaust valves closed). Continue to turn theengine another 30 degrees to the mark on the flywheel "Valves 1 & 6". Adjust the valveyokes and valves of the number one cylinder at this position. Thereafter, continue toturn the engine through its firing order sequence, adjusting the valves at each "Valve"mark. The flywheel is marked at 120-degree increments to indicate the engine positionat which the valves must be adjusted. It is necessary to turn the engine through two

complete revolutions in order to adjust the valves completely on an engine. Access tothe valve adjustment markings on the flywheel is achieved by removing the cover fromthe bottom of the flywheel housing. Tool No. J 38587, which engages the flywheelthrough an access hole in the flywheel housing, is recommended to rotate the engine.

Valve adjustments are made in two stages. The exhaust valve yoke is adjusted first,and then the valve lash. Rotate the engine in the direction of normal rotation until thevalve adjustment marking is aligned in the center of the access window.

SPECIAL TOOLS REQUIRED

Engine Barring Socket J 38587-A

Torque Wrench J 24407

T-Handle Torque Screwdriver J 29919 (Torque value preset to 6 lb-in)

Hex Internal Bit, 5 mm

Crow's Foot Wrench, 8 mm 3/8-Inch DriveCrow's Foot Wrench, 13 mm 3/8-Inch Drive

Crow's Foot Wrench, 14 mm 3/8-Inch Drive

Adapter, 3/8-Inch to 1/4-Inch

Drive Extension, 1/4-Inch

Figure 2 -- Flywheel Valve Adjustment Markings




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VALVE YOKE AND VALVE LASH ADJUSTMENT FOR NON-BRAKEENGINES

Valve Yoke Adjustment Procedure (Non-Brake Engines)

Adjust the valve yokes at the exhaust valve positions using the following procedure. Asthese engines are equipped with the self-leveling pinless valve yokes at the inlet

positions, only the exhaust valve yokes need to be adjusted.

Make sure that adjusting screws are retracted upward in the rocker arms. If theadjusting screws are not retracted and extend too far below the rocker arm, the pushrods can be bent and valve lifter rollers damaged or broken when tightening the rockerarm assembly brackets.

1. Using engine barring socket J 38587-A, or equivalent, manually rotate engine innormal rotation direction until pointer in flywheel housing aligns with the valves 1and 6 marks on the flywheel and the No. 1 piston is at top dead center on thecompression stroke.

Valve lash must be set using the valve adjustment marks on the engine flywheel,which are at 30 degrees ATC. This ensures that the lifter is on the camshaft base

circle and not on the brake ramp portion of the lobe.

2. Loosen the rocker arm adjusting screw jam nuts and back out the adjusting screwsseveral turns. ASET engine rocker arm adjusting screws have a 5 mm internalhex at the screw head.

Figure 3 -- Loosening Exhaust Rocker Arm Locknut and Backing Out Adjusting Scr




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3. Loosen the No. 1 cylinder yoke adjusting screw jam nuts for the exhaust valves.Yoke adjusting screws for non-brake engines have a screwdriver slot at the top.

4. Exert moderate force on the valve yoke by pressing on the rocker arm slipper end.

Turn the yoke adjusting screw clockwise until it makes solid contact with theoutboard valve stem tip (a light drag should be felt on the adjusting screw).

5. After the adjusting screw makes solid contact with the valve stem, turn the screwclockwise an additional 30 degrees.

A 30-degree turn is equal to 1/2 of a flat on the adjusting screw jam nut.

Figure 4 -- Loosening Exhaust Valve Yoke Adjusting Screw Locknut

Figure 5 -- Turning Yoke Adjusting Screw Until It Contacts Valve Stem

Figure 6 -- Turning Adjusting Screw an Additional 30 Degrees




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6. Hold the valve yoke adjusting screw in this position and tighten the adjustingscrew jam nut to the specified torque, 33 lb-ft (45 Nm), using torque wrench J24407, or equivalent.

7. Check the valve yoke adjustment as follows:

a. Insert 0.010-inch (0.25 mm) thickness gauges between the inboard andoutboard valve stem tips and the valve yoke.

b. Exert moderate force on the yoke by pressing on the rocker arm slipper end.An equal "drag" should be felt on both thickness gauges. If drag is not equal,readjust the valve yoke.

Figure 7 -- Yoke Adjusting Screw and Jam Nut (Slotted Screw Shown)

Figure 8 -- Checking Yoke Adjustment




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Inlet and Exhaust Valve Lash Adjustment (Non-Brake Engines)

The following procedure was developed for adjusting exhaust valve lash on enginesequipped with spring-loaded push rods. This same procedure, however, can be used foradjusting inlet valve lash, even though the inlet valves use standard push rods. If thetorque screwdriver is not available, an alternate procedure that does not require thetorque screwdriver is outlined in the "Inlet and Exhaust Valve Lash Adjustment for Non-Brake Engines (Alternate Procedure)" section that follows.

1. Loosen the rocker arm nut and back out the adjusting screws at the No. 1 cylinder

a couple of turns and thread the new flange-head jam nuts on the adjustingscrews, leaving them loose so that adjustments can be made.

2. Push down on the adjusting screw side of the rocker arm and insert theappropriate thickness gauge (inlet 0.016-inch [0.406 mm], exhaust 0.024-inch [0.610 mm]) between the slipper face of the rocker arm and the top of thevalve yoke. Leave the thickness gauge in place.

Figure 9 -- Inserting Thickness Gauge




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3. Using the torque screwdriver, J 29919 or equivalent, slowly turn the rocker arm

adjusting screw clockwise. At the exhaust locations, the push rod spring will

compress as the adjusting screw is being tightened. At the inlet locations, theextra clearance will be "taken-up" as the adjusting screw is being tightened.

4. Continue tightening the adjusting screw until the torque screwdriver clicks. At theexhaust locations, the push rod spring seats are now in contact and the push rod issolid and the valve lash is now properly set. Do not tighten the adjusting screw anyfurther. At the inlet locations, when the torque screwdriver clicks, all excessive lashhas been "taken-up" and inlet lash is now set to the thickness of the feeler gauge.

The torque screwdriver may allow the valve adjusting screw to loosen slightlywhen it clicks at the pre-set torque. Always recheck valve lash adjustment asdescribed in step 7.

5. Remove the torque screwdriver and hold the adjusting screw in position with a

1. Rocker Arm 2. Feeler Gauge

Figure 10 -- Adjusting Exhaust Valve Lash




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standard 5 mm Allen wrench to keep it from turning. Tighten the flange-head jamnut to specification, 45 lb-ft (61 Nm).

6. Remove the thickness gauge.

7. Check the exhaust valve lash adjustments by pushing down on the adjusting screwend of the rocker arm to compress the push rod spring and inserting theappropriate thickness gauge (inlet 0.016 inch [0.406 mm]; exhaust 0.024inch [0.610 mm]) between the rocker arm slipper face and the valve yoke.Continue exerting downward pressure on the rocker arm to keep the push rodspring compressed while checking the adjustment. The thickness gauge should besnug between the slipper face and valve yoke. If not, repeat the adjustmentprocedure. Inlet valve lash adjustment may be checked in the same manner,except there is no push rod spring to compress.

When exerting pressure on the rocker arm to keep the push rod springcompressed, drag on the thickness gauge should feel normal, as when performingan adjustment on an engine that is not equipped with spring-loaded push rods.When hand-pressure is released, a significant increase in drag on the thicknessgauge will be felt due to the force of the push rod spring.

Figure 11 -- Tightening Adjusting Screw Jam Nut

Figure 12 -- Checking Valve Lash Adjustment




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Inlet and Exhaust Valve Lash Adjustment for Non-Brake Engines (AlternateProcedure)

If an oz-in or lb-in torque screwdriver or torque wrench is not available, valve lash canbe adjusted (for both brake and non-brake engines) in the same manner as describedabove (by installing the appropriate thickness gauge and tightening the adjustingscrew), but using careful hand-pressure to compress the push rod spring instead of the6 lb-in torque screwdriver.

Use a 5 mm internal hex wrench in place of the torque screwdriver to turn the adjustingscrew. Turn the screw clockwise until a large increase in resistance is felt, indicatingthat the push rod is fully compressed and the internal stops of the push rod upper andlower spring seats are bottom against each other. No further tightening force is to beapplied to the adjusting screw, or an inaccurate valve adjustment may result. At that

point, valve lash should be properly set and the adjusting screw jam nut can betightened to 45 lb-ft (61 Nm).

Always recheck the adjustment by exerting downward pressure by hand on theadjusting screw and on the rocker arm to fully compress the push rod while recheckingwith the thickness gauge. When holding the push rod compressed for the lashovercheck, normal thickness gauge drag will result. However, after the valve lash is set,and downward pressure on the rocker arm is released, the push rod spring pressure willput increased drag on the thickness gauge.

Continuation of Adjustments for Remaining Cylinders

1. Using a barring socket, manually rotate the engine crankshaft ( Figure 13 -- ValveAdjustment Markings on Flywheel ) in normal rotation direction 120 degrees untilthe center of the timing pointer hole in the flywheel housing aligns with the "2 and5" mark on the flywheel and the No. 5 piston is on the compression stroke.

1. Rocker Arm 2. Feeler Gauge

Figure 13 -- Valve Adjustment Markings on Flywheel




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2. Adjust the final intake and exhaust valve lash for cylinder No. 5 as described forcylinder No. 1. Continue this procedure for each of the remaining cylinders,following the engine firing order sequence, 1-5-3-6-2-4.

VALVE YOKE, VALVE LASH AND BRAKE LASH ADJUSTMENT FOR J-TECH BRAKE-EQUIPPED ENGINES

Valve Yoke Adjustment Procedure (J-Tech Brake Engines)

Adjust the valve yokes at the exhaust valve positions using the following procedure. Asthese engines are equipped with the self-leveling pinless valve yokes at the inletpositions, only the exhaust valve yokes need to be adjusted.

Make sure that adjusting screws are retracted upward in the rocker arms. If theadjusting screws are not retracted and extend too far below the rocker arm, the pushrods can be bent and valve lifter rollers damaged or broken when tightening the rockerarm assembly brackets.

Verify that the slave piston adjusting screws are fully retracted and that all the sphericalam nuts are turned down snug against the rocker arms before rotating the engine

crankshaft for valve lash adjustment. Rotating the engine crankshaft with the sphericalam nuts loose, or the slave piston adjusting screws not fully retracted, could damagethe brake master pistons or damage or break the ceramic lifters.

1. Using engine barring socket J 38587-A, or equivalent, manually rotate engine innormal rotation direction until pointer in flywheel housing aligns with the valves 1and 6 marks on the flywheel and the No. 1 piston is at top dead center on thecompression stroke.

1. Barring Socket J 38587-A

2. Flywheel Housing

3. Flywheel




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Valve lash must be set using the valve adjustment marks on the engine flywheel,which are at 30 degrees ATC. This ensures that the lifter is on the camshaft basecircle and not on the brake ramp portion of the lobe.

2. Loosen the rocker arm adjusting screw jam nuts and back out the adjusting screwsseveral turns. ASET engine rocker arm adjusting screws have a 5 mm internalhex at the screw head.

For clarity, most of the illustrations in this section show adjustments beingperformed without the Jake brake units being installed. However, the Jake unitsmust be installed to correctly adjust the inlet and exhaust valve lash.

3. Loosen the No. 1 cylinder yoke adjusting screw jam nuts for the exhaust valves.Yoke adjusting screws used with the J-Tech brake have a 8 mm hex at the top ofthe screw body.

Figure 14 -- Loosening Exhaust Rocker Arm Locknut and Backing Out Adjusting Sc

Figure 15 -- Loosening Valve Yoke Adjusting Screw Locknut




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4. Exert moderate force on the valve yoke by pressing on the rocker arm slipper end.Turn the yoke adjusting screw clockwise until it makes solid contact with theoutboard valve stem tip (a light drag should be felt on the adjusting screw).

Engines equipped with a J-Tech engine brake will have an actuator pin adjustingscrew in the exhaust yoke.

Do not allow anything to press down on the actuating pin during adjustment. The pin must be fully extended, approximately 1/4 inch (6.350 mm) above the top ofthe hollow adjusting screw. If the pin is held down and not fully extended, animproper adjustment and engine failure will result.

5. After the adjusting screw makes solid contact with the valve stem, turn the screwclockwise an additional 30 degrees.


Figure 16 -- Turning Yoke Adjusting Screw Until It Contacts Valve Stem




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6. Hold the valve yoke adjusting screw in this position and tighten the adjustingscrew jam nut to the specified torque, 33 lb-ft (45 Nm), using torque wrench J24407, or equivalent.

7. Check the valve yoke adjustment as follows:

a. Insert 0.010-inch (0.25 mm) thickness gauges between the inboard andoutboard valve stem tips and the valve yoke.

b. Exert moderate force on the yoke by pressing on the rocker arm slipper end.An equal "drag" should be felt on both thickness gauges. If drag is not equal,readjust the valve yoke.

Figure 17 -- Turning Adjusting Screw an Additional 30-Degree Turn

Figure 18 -- Yoke Adjusting Screw and Jam Nut

Figure 19 -- Checking Yoke Adjustment




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Exhaust Valve Lash Adjustment (J-Tech-Equipped Engines)

When adjusting exhaust valve lash on an engine equipped with a J-Tech engine brake,the same procedure is used as on a non-brake-equipped engine except that the 14 mm

crow's foot wrench, adapter and long extension are required in place of the screwdriver.These tools are required because the spherical nut covers the top of the adjustingscrew, so the 14 mm hex at the bottom side of the adjusting screw must be used.

The J-Tech exhaust rocker arm adjusting screw spherical jam nut is a through-hardened nut. When tightening these nuts, be aware of the following:

Always use the proper 20 mm size wrench to tighten the spherical jam nut.Tighten the nut to 45 lb-ft (61 Nm). Using an improper size wrench will lead to

jam nut breakage.

Overtightening the spherical jam nut when adjusting the valves may result in jamnut breakage. If there is too much or too little drag on the thickness gauge, loosenthe jam nut and readjust valve lash. Do not overtighten the spherical nut in anattempt to obtain correct valve lash.

Figure 20 -- Adjusting Valve Lash on Engines Equipped with a J-Tech Engine Brake




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Alternate Valve Lash Adjustment Procedure (J-Tech Brake Engines)

If an oz-in or lb-in torque screwdriver or torque wrench is not available, valve lash canbe adjusted (for both brake and non-brake engines) in the same manner as describedabove (by installing the appropriate thickness gauge and tightening the adjusting

screw). Use a 5 mm internal hex wrench in place of the torque screwdriver to turn theadjusting screw. Turn the screw clockwise until a large increase is felt, indicating thatthe push rod is fully compressed and the spring has hit the stop. At this point, valvelash should be properly set and the adjusting screw jam nut can be tightened to 45 lb-ft(61 Nm). Always recheck the adjustment by exerting downward pressure by hand onthe adjusting screw end of the rocker arm to fully compress the push rod whilerechecking with the thickness gauge.

Brake Lash Adjustment (J-Tech Brake Engines)

The engine brake lash specification is based on the reset screw part number. All ASETengines utilize reset screw part No. 032053A, which requires a 0.021-inch (0.533 mm)lash specification. Adjust the engine brake using the following procedure:

1. If not previously done, use a 3/4-inch wrench to loosen the slave piston adjustingscrew (reset screw) jam nut. Back-off the adjusting screw until the slave pistonseats at the top of its bore.

2. Place the appropriate 0.021-inch (0.533 mm) thickness gauge between the slavepiston stem and the top of the actuator pin in the yoke adjusting screw.

3. Turn the slave piston adjusting screw to set the brake lash.

4. Tighten the jam nut to specification, 25 lb-ft (34 Nm).

DO NOT overtighten the slave piston adjusting screw jam nut. To do so will causemalfunction of this screw in performing the brake reset function and possibly resultin reset screw breakage.

Figure 21 -- J-Tech Exhaust Valve Rocker Arm and Yoke




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1. Barring Socket J 38587-A 3. Flywheel




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2. Adjust the final intake and exhaust valve lash, and engine brake slave piston lash

for cylinder No. 5 as described for cylinder No. 1. Continue this procedure for eachof the remaining cylinders, following the engine firing order sequence, 1-5-3-6-2-4.

VALVE YOKE, BRAKE LASH AND VALVE LASH ADJUSTMENT FORENGINES EQUIPPED WITH MACK POWERLEASH ENGINE BRAKE

Valve adjustments are made in firing order sequence (1-5-3-6-2-4) with the engine cold(coolant temperature below 100F [38C]), not running and with the piston at 30degrees after top dead center on the compression stroke (inlet valve closed). Theflywheel is marked in 120-degree increments to indicate markings on the flywheel byremoving the cover from the bottom of the flywheel housing. Tool J 38587-A, whichengages the flywheel through the access hole in the flywheel housing, is recommendedto rotate the engine.

Engines equipped with PowerLeash brake have TWO ADJUSTING SCREWS located oneach exhaust rocker arm and a different procedure. The rocker arm adjusting screw atthe push rod was traditionally used for adjusting valve lash. With PowerLeash , thisadjusting screw is used for BRAKE LASH ADJUSTMENT. A second adjusting screw,located at the other end of the rocker arm just above the valve yoke is used for VALVELASH ADJUSTMENT. The push rod must be fully compressed and the brake lashadjustment set first, and then with the push rod remaining fully compressed and thebrake lash feeler gauge remaining in-place, the exhaust valve lash adjustment isperformed.

Adjust the valve yokes at the exhaust valve positions using the following procedure. Asthese engines are equipped with the self-leveling pinless valve yokes at the inletpositions, only the exhaust valve yokes need to be adjusted. Valve yoke balance,engine brake lash and valve lash must be adjusted in the following order:

a. Valve yoke balance is adjusted first.

b. Engine brake actuator lash is adjusted second, using the adjusting screw on thepush rod side of the rocker arm.

c. Valve lash is adjusted last, using the adjusting screw located over the valve yoke.

Valve Yoke Adjustment Procedure ( PowerLeash Brake Engines)

2. Flywheel Housing




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Yoke adjusting screws used with the PowerLeash brake have a screwdriver slot at thetop.

1. Loosen the engine brake hydraulic actuator adjusting screw locknut (located on thepush rod end of the exhaust rocker arm) and back the adjusting screw out several

turns.

2. Loosen the exhaust valve yoke screw locknut.

3. Exert moderate force on the exhaust valve yoke by pressing on the end of theexhaust rocker arm above the yoke. Turn the yoke adjusting screw clockwise until

it solidly contacts the outboard valve stem tip (a light drag should be felt on theadjusting screw).

Figure 23 -- Loosening Hydraulic Actuator Locknut and Backing Out Adjusting Scr

Figure 24 -- Loosening Exhaust Valve Yoke Adjusting Screw Locknut

Figure 25 -- Turning the Exhaust Valve Yoke Adjusting Screw Until it Contacts ValStem




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4. After the adjusting screw solidly contacts the valve stem tip, turn the screwclockwise an additional 30 degrees.


5. While holding the valve yoke adjusting screw in this position, tighten the adjustingscrew locknut to 33 lb-ft (44 Nm).

Figure 26 -- Turning Adjusting Screw an Additional 30-Degree Turn

Figure 27 -- Tightening Valve Yoke Locknut




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6. Check the valve yoke adjustment by inserting 0.010-inch (0.25 mm) thicknessgauges between the inboard and outboard valve stem tips and the valve yoke. Itwill be necessary to pull the valve yoke up to insert the thickness gauge betweenthe valve stem tip and the yoke.

Inserting the thickness gauges may be made easier if the gauge is inserted underthe inboard portion of the valve yoke first, then under the outboard portion.

7. While exerting a moderate force on the rocker arm end above the yoke, check thatan equal "drag" is felt on both thickness gauges. If drag is not equal, readjust thevalve yoke.

Figure 28 -- Inserting Thickness Gauge

Figure 29 -- Checking Valve Yoke Adjustment




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Brake Actuator Lash Adjustment ( PowerLeash Brake Engines)

Spring-loaded push rods are used at the exhaust valve locations. In order to properlyadjust the engine brake hydraulic actuator lash, the push rod springs must be

compressed. In addition to the hand tools normally used to adjust valves, a T-handletorque screwdriver (tool No. J 29919) with a 5 mm internal hex bit is required. Thistorque screwdriver is preset to 6 lb-in.

It is mandatory that the T-handle torque screwdriver (tool No. J 29919) be used to

adjust the MACK PowerLeash engine brake hydraulic actuator.The engine brake hydraulic actuator must be adjusted prior to adjusting the exhaustvalve lash.

1. Loosen the engine brake adjusting screw (located above the push rod) locknut andback the adjusting screw out several turns.

Figure 30 -- T-Handle Torque Screwdriver, J 29919




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2. Loosen the swivel-head adjusting screw locknut (located on the valve actuatingside of the exhaust rocker arm) and back the adjusting screw out a couple ofturns.

3. Push down on the push rod end of the exhaust rocker arm to fully depress thepush rod spring, then insert a 0.045-inch (1.14 mm) thickness gauge between thehydraulic actuator plunger and the actuator pin located above the inboard exhaustvalve.

It is recommended that a dull knife-edge be ground onto the leading edge of the0.045-inch (1.14 mm) thickness gauge to facilitate inserting it between the brakeplunger and the actuator pin. Doing this will eliminate the need for backing off theadjusting screw to insert the thickness gauge. A relief is cut in the lower surface ofthe rocker arm to provide clearance for inserting the thickness gauge. Thethickness gauge must be installed from the side of the rocker arm that faces therear of the engine, and at the angle shown in the previous illustration.

4. Using the T-handle torque screwdriver (tool No. J 29919), slowly turn the actuator

Figure 31 -- Loosening Swivel-Head Adjusting Screw

Figure 32 -- Inserting Thickness Gauge Between Brake Plunger and Actuator Pi




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adjusting screw clockwise. As the screwdriver is being turned, the push rod springwill be compressed. Continue tightening the adjusting screw until the screwdriverclicks. At the point that the screwdriver clicks, the push rod spring seats are incontact and the push rod is solid. At that point, hydraulic actuator lash is properlyset. Do not tighten the screwdriver any further.

The torque screwdriver may allow the adjusting screw to loosen slightly whenit "clicks" at the pre-set torque. It is important to develop a "feel" for whenthe screwdriver click occurs and feel for the actual setting of the lash. Todevelop a feel for when the screwdriver will click, slowly turn the screwdriverthrough the function once or twice, and for the third time, bring thescrewdriver just to the point before it clicks. Also, at no time should thescrewdriver be turned clockwise after the click has occurred. Always recheckthe adjustment.

When tightening the adjusting screw, it is important to make sure that the

adjusting screw jam nut is NOT bottomed against the rocker arm, and thatthe swivel-head adjusting screw at the nose end of the rocker arm is NOT incontact with the valve yoke.

If either the push rod spring or the brake actuator plunger are notcompressed, brake lash is not set correctly and the adjustment proceduremust be repeated.

5. Remove the T-handle torque screwdriver, then use a hex-bit screwdriver to holdthe adjusting screw in position. Use an accurately calibrated torque wrench totighten the jam nut to 45 lb-ft (61 Nm).

Figure 33 -- Adjusting Engine Brake Hydraulic Actuator Lash

Figure 34 -- Tightening Adjusting Screw Jam Nut




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After completing the brake plunger lash adjustment, leave the 0.045-inch (1.14mm) thickness gauge in place. This keeps the plunger and push rod springcompressed so that the exhaust valve lash can be adjusted.

Exhaust Valve Lash Adjustment ( PowerLeash Brake Engine)

1. With the 0.045-inch (1.14 mm) thickness gauge in place between the valve yokeand the hydraulic actuator plunger, insert a 0.024-inch (0.610 mm) thicknessgauge between the adjusting screw "foot" and the valve yoke. Using a 5 mm Allenwrench, turn the adjusting screw until a light "drag" is felt on the thickness gauge.

2. Holding the adjusting screw in position, use an accurately calibrated torque wrenchto tighten the jam nut to 45 lb-ft (61 Nm).

Figure 35 -- Adjusting Exhaust Valve Lash

Figure 36 -- Tightening Swivel-Head Adjusting Screw Jam Nut




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3. Remove the thickness gauges from between the swivel-head adjusting screw andvalve yoke, and from between the brake lash adjuster plunger and the actuatingpin.

4. Recheck the exhaust valve lash adjustment by pressing down on the push rod end

of the rocker arm and inserting the 0.024-inch (0.610 mm) thickness gaugebetween the swivel-head adjusting screw and the valve yoke. If the adjustment isnot correct, both engine brake and exhaust valve lash must be re-checked andreadjusted as required.

Inlet Valve Adjustment ( PowerLeash Brake Engines)

Inlet valve lash is adjusted in the same manner as non-brake engines.




1. Barring Socket J 38587-A 3. Flywheel




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2. Adjust the final intake valve lash, engine brake piston lash, and exhaust valve lash

for cylinder No. 5 as described for cylinder No. 1. Continue this procedure for eachof the remaining cylinders, following the engine firing order sequence, 1-5-3-6-2-4.

Electronic Unit Pump (EUP) Calibration

[221 GP]

Whenever an electronic unit pump(s) is replaced in an engine, it is necessary torecalibrate the pump(s) by entering the calibration code into the engine electroniccontrol unit (EECU). The calibration code is a four-digit number that can be found onthe data plate of each individual unit pump. This calibration code is then entered byusing a personal computer that is running the V-MAC Service Support Software.

The four-digit calibration code can be found on the EUP data plate, shown after theletters "CAL" for early production EUPs. For later-production EUPs, the calibration codeis still found in the same location on the data plate (next to the word MACK), only theidentification letters "CAL" have been eliminated to provide room for larger bar codes.

2. Flywheel Housing

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