Centinel System – Repair Manual – 001-088   Engine Base Timing

Two front gear train combinations are currently utilized on the Signature™, ISX, and QSX15 engines. Signature™, ISX3, ISX2, and QSX15 engines use a scissor gear for the lower idler gear and the injector cam gear. ISX1 does not use a scissor gear at the idler location.

ISX2 engines built between January, 1999 and January, 2000 utilized a scissor gear for the lower idler gear only. The injector cam gear was a straight cut spur gear, similar to the ISX1. After January, 2000, the ISX2 has scissor gears for both the cam and lower idler.

This procedure describes the removal, inspection, and installation of the different gear combinations.

View shown is from left to right and top to bottom.

• Valve camshaft gear
• Injector camshaft gear
• Adjustable idler gear
• Lower idler gear
• Accessory gear
• Crankshaft gear.

View shown is from left to right and top to bottom.

• Valve camshaft gear
• Injector camshaft scissor gear
• Adjustable idler gear
• Lower idler scissor gear
• Accessory gear
• Crankshaft gear.

WARNING  Do not attempt to remove any gears before reading scissor gear definitions. Serious personal injury or engine damage can result if instructions are not followed.

The following terms describe the conditions of the scissor gears for removal, installation, and operation.

Unloaded:

The gear will be unloaded when removing, installing, and setting gear backlash.

Unload the gear by backing out two gear adjusting screws until the gear teeth align.

The idler scissor gear is loaded when the gear backlash is set.

Loaded:

The gear teeth are loaded (functional) and are spread between the mating gear teeth.

The gear is loaded by tightening all of the adjusting screws. The gear teeth will be spread and no movement will be felt against the valve cam gear. The gear will be in the loaded condition for engine operation.

QSX15 engines are equipped with dual vibration dampers. The crank pin mark is located on the damper closest to the engine.

Rotate the crankshaft clockwise until the ”insert pin” mark on the outside diameter of engine vibration damper is aligned with the mark on the gear housing.

Insert the pin in the hole in the pin boss.

The green band on the timing pin will be lined up with the surface of the timing pin boss of the block.

The pin is not correctly seated in the crank notch if the green band is either completely visible outside the block, or is not visible at all.

Lock the crankshaft in place with the crankshaft locking pin, Part Number 3163020.

Remove the rocker lever cover and gasket.Refer to Procedure 003-011 (Rocker Lever Cover) in Section 3.

Disconnect and remove the engine brake wiring harness.Refer to Procedure 020-015 (Engine Brake Wiring Harness) in Section 20.

Removing the rocker lever shafts removes the load from the camshafts. This allows the camshafts to be rotated when installing the timing wedges and the camshaft gears are not installed.

Remove the rocker lever shafts.Refer to Procedure 003-009 (Rocker Lever Assembly) in Section 3.

Removal of the lower front cover is not required when setting the gear backlash on engines that utilize all non-scissor gears. An access hole is provided to insert a shim between the lower non-scissor idler gear and the adjustable idler gear. The access hole is sealed with a plug.

It will be helpful to push the gear cover plug out from the rear. It is not necessary to remove the lower gear cover to push out the plug.

Remove the upper gear cover.Refer to Procedure 001-079 (Gear Cover, Upper) in Section 1.

Remove the lower gear cover, if needed.Refer to Procedure 001-080 (Gear Cover, Lower) in Section 1.

The injector camshaft scissor gear must be unloaded during removal of the valve camshaft gear. To unload the gear, two of the gear screws must be backed out far enough to allow the teeth on the scissor gear to be aligned.

Unload the injector camshaft scissor gear.

Remove the valve camshaft gear mounting capscrew and washer.

Early production engines were not equipped with puller holes in the valve camshaft gear. A 3-jaw gear puller must be used for gears that do not have puller holes. The injector and valve gear puller, Part Number 3163069, can be used for gears that have puller holes.

Install the gear puller, Part Number 3163069.

Install the valve camshaft gear mounting capscrew completely.

Loosen the capscrew two turns.

Use the gear puller to remove the valve camshaft gear from the camshaft nose.

Remove the puller.

Do not completely remove the camshaft gear mounting capscrew when the 3-jaw puller is used. The capscrew serves as a safety catch by preventing the gear from shooting off of the camshaft nose.

Remove the valve camshaft gear mounting capscrew, spacer, and valve camshaft gear.

WARNING  When using solvents, acids, or alkaline materials for cleaning, follow the manufacturer’s recommendations for use. Wear goggles and protective clothing to reduce the possibility of personal injury.

WARNING  Some solvents are flammable and toxic. Read the manufacturer’s instructions before using.

Use a lint free cloth and solvent to clean the Loctite™ residue from the nose of the camshaft.

CAUTION  Remove the rear injector camshaft cover plate before removal of the injector camshaft gear or camshaft. The force required to remove the camshaft gear creates sufficient backwards movement of the camshaft to crack the rear cover plate.

Remove the injector camshaft rear cover plate.

Remove the injector camshaft scissor gear mounting capscrew and washer.

Install gear puller, Part Number 3163069.

Install the injector camshaft scissor gear mounting capscrew. Loosen the capscrew one turn.

Use the gear puller to force the injector camshaft scissor gear off the camshaft taper.

Remove the gear puller.

Remove the capscrew.

Remove the injector camshaft scissor gear.

WARNING  When using solvents, acids, or alkaline materials for cleaning, follow the manufacturer’s recommendations for use. Wear goggles and protective clothing to reduce the possibility of personal injury.

WARNING  Some solvents are flammable and toxic. Read the manufacturer’s instructions before using.

Use a lint free cloth and solvent to clean the Loctite™ residue from the nose of the camshaft.

CAUTION  Remove the rear injector camshaft cover plate before removal of the injector camshaft gear or camshaft. The force required to remove the camshaft gear creates sufficient backwards movement of the camshaft to crack the rear cover plate.

Remove the injector camshaft rear cover plate.

Remove the injector camshaft gear mounting capscrew and washer.

Install gear puller, Part Number 3163069.

Install the injector camshaft gear mounting capscrew. Loosen the capscrew one turn.

Use the gear puller to force the injector camshaft gear off the camshaft taper.

Remove the gear puller.

Remove the capscrew.

Remove the injector camshaft gear.

WARNING  When using solvents, acids, or alkaline materials for cleaning, follow the manufacturer’s recommendations for use. Wear goggles and protective clothing to reduce the possibility of personal injury.

WARNING  Some solvents are flammable and toxic. Read the manufacturer’s instructions before using.

Use a lint free cloth and solvent to clean the Loctite™ residue from the nose of the camshaft.

The adjustable idler gear shaft can fall out when the adjustable idler gear is removed.

Remove the retainer capscrews, retainer, gear, and adjustable idler gear shaft.

Remove the mounting spacer.

The lower idler scissor gear must be unloaded during removal. To unload the gear, two of the gear screws must be backed out far enough to allow the teeth on the scissor gear to be aligned.

Unload the lower idler scissor gear.

Remove the idler scissor gear capscrews.

Remove the retainer, gear, shaft, and thrust bearing.

Remove the idler non-scissor gear capscrews and retainer.

Remove the gear, shaft, and thrust bearing.

Inspect the gear teeth on all gears for pitting, heavy wear, or breakage.

Inspect the gear for cracking around the puller holes.

Replace any pitted, heavily worn, or damaged gear and inspect the mating gear for associated damage.

Inspect the lower idler shaft and adjustable idler shaft for heavy wear.

Measure the idler shafts outside diameter.

Lower Idler Shaft Outside Diameter

Adjustable Idler Shaft Outside Diameter

Inspect the lower idler gear bore and adjustable idler gear bore for heavy wear.

Measure the inside diameter of the lower idler and adjustable idler gear bores.

Lower Idler Gear Bore Inside Diameter

Adjustable Idler Gear Bore Inside Diameter

Timing Wedges:

The timing code is located on the engine dataplate.

• First number – injector wedge
• Second number – valve wedge.

Make sure the wedges with the proper angles are used and that the wedges are properly seated in their installed position.

Insert the correct timing wedge to lock the injector camshaft. Lightly tap the top of the timing wedge with a mallet to be sure it is properly seated.

WARNING  Do not drive the wedges into place. Engine damage can occur.

Make sure the wedges with the proper angles are used and that the wedges are properly seated in their installed position.

Insert the correct timing wedge to lock the valve camshaft. Lightly tap the top of the timing wedge with a mallet to be sure it is properly seated.

The lower scissor idler gear must be unloaded during installation. To unload the gear, two of the gear screws must be backed out far enough to allow the teeth on the scissor gear to be aligned.

Apply Lubriplate™ to the thrust bearing, shaft, and lower scissor idler gear.

Install the thrust bearing, shaft, and lower scissor idler gear. The shaft must be installed with the word “TOP” (stamped on the end of the shaft) toward the top of the engine.

The lower idler scissor gear front retainer plate is larger in diameter than the adjustable idler retainer plate. The slots in the plate go toward the scissor gear

Install the retainer and capscrews.

Tighten all capscrews in a star pattern.

CAUTION  Make sure all the scissor gear screws are tightened to the proper torque so that they do not back out during engine operation. Severe engine damage can occur.

Load the lower idler scissor gear by tightening all of the gear screws.

Apply Lubriplate™ to the thrust bearing, shaft, and lower non-scissor idler gear.

Install the thrust bearing, shaft, and lower non-scissor idler gear. The shaft must be installed with the word “TOP” (stamped on the end of the shaft) toward the top of the engine.

The lower idler non-scissor gear front retainer plate is larger in diameter than the adjustable idler retainer plate. The slots in the plate go toward the scissor gear

Install the retainer and capscrews.

Tighten all capscrews in a star pattern.

The spacer plate is doweled to the block with two standard dowels.

Install the mounting spacer plate.

Apply Lubriplate™ to the spacer, shaft, and adjustable idler gear.

It is possible to install the shaft in an incorrect orientation; however, it will not be possible to set the gear backlash correctly.

Install the spacer, shaft and adjustable idler gear. The shaft must be installed with the word “TOP” (stamped on the front face of the shaft) oriented toward the top of the engine.

The adjustable idler front retainer plate is smaller in diameter than the lower idler scissor gear retainer plate. The slots on the retainer plate go toward the gear.

The adjustable idler gear is installed loosely, because it is moved into its final position later in the timing process.

Install the retainer and capscrews. Finger-tighten the capscrews and then loosen by one “flat,” which is 60 degrees.

Install the injector camshaft rear cover plate.

CAUTION  The injector camshaft nose and injector camshaft scissor gear must be clean and dry prior to assembly. Wipe off the taper surface with a clean lint-free cloth and apply a thin coat of Loctite™ 609, Part Number 3823718, to the inside diameter of the camshaft gear. Use care not to contaminate the joint with oil prior to assembly or engine damage may occur.

The injector camshaft scissor gear must be unloaded during installation. To unload the gear, two of the gear screws must be backed out far enough to allow the teeth on the scissor gear to be aligned.

Apply a thin coat of Loctite™ 609, Part Number 3823718, to the inside diameter of the camshaft gear.

The injector camshaft scissor gear needs to be fully engaged on the camshaft nose taper, yet loose enough so it can rotate on the camshaft nose.

Install the injector camshaft scissor gear loosely on the camshaft nose taper.

The injector camshaft scissor gear mounting washer is larger in diameter than the valve camshaft mounting washer.

Install the mounting washer and capscrew.

Finger-tighten the capscrew and then loosen by one “flat,” which is 60 degrees.

The injector camshaft scissor gear is still loose at this point, to allow the adjustable idler gear to be properly positioned.

Do not seat the gear.

Install the injector camshaft rear cover plate.

Apply a thin coat of Loctite™ 609, Part Number 3823718, to the inside diameter of the camshaft gear.

The injector camshaft non-scissor gear needs to be fully engaged on the camshaft nose taper, yet loose enough so it can rotate on the camshaft nose.

Install the injector camshaft non-scissor gear loosely on camshaft nose taper.

The injector camshaft non-scissor gear mounting washer is larger in diameter than the valve camshaft mounting washer.

Install the mounting washer and capscrew.

Finger-tighten the capscrew and then loosen by one “flat,” which is 60 degrees.

The injector camshaft non-scissor gear is still loose at this point to allow the adjustable idler gear to be properly positioned.

Do not seat the gear.

Apply a thin coat of Loctite™ 609, Part Number 3823718, to the inside diameter of the camshaft gear.

The valve camshaft gear needs to be fully engaged on the camshaft nose taper, yet loose enough so it can rotate on the camshaft nose.

Install the valve camshaft gear loosely on the camshaft nose taper.

The valve camshaft mounting washer is smaller in diameter than the injector camshaft scissor gear mounting washer.

Install the mounting washer and capscrew.

Finger-tighten the capscrew and then loosen by one “flat,” which is 60 degrees.

The valve camshaft gear is still loose at this point to allow the adjustable idler gear to be properly positioned.

Do not seat the gear.

CAUTION  Do not set backlash between the adjustable idler gear and the lower scissor idler gear. Severe engine damage can occur.

This backlash step works with the scissor type injector camshaft gear and lower idler gear, and the non-scissor injector camshaft gear with a scissor type lower idler gear.

The injector camshaft scissor gear must still be unloaded during this step. To unload the gear, two of the gear screws must be backed out far enough to allow the teeth on the scissor gear to be aligned.

Insert, as shown, a narrow shim (0.25 mm [0.010 in]) into the gear teeth mesh between the adjustable idler gear and the wide (rear side) gear of the injector camshaft scissor gear.

Shim Tolerance

NOTE: The gear backlash set procedure for engines that have a non-scissor injector camshaft gear and a scissor type lower idler gear is the same as that of engines that utilize two scissor type gears.

Use hand pressure, only, to move the adjustable idler gear toward the center of the engine (into mesh), so there is no gap on either side of the shim.

Both of the camshaft gears will rotate slightly on the camshafts during this step.

Slight drag will be felt on the shim while pulling the shim in and out.

Removal of the lower front cover is not required when setting the gear backlash on engines that utilize all non-scissor gears. An access hole is provided to insert a shim between the lower non-scissor idler gear and the adjustable idler gear. The access hole is sealed with a plug. The plug can be pushed out from the rear side without removing the gear cover.

The following procedure will be shown with the lower gear cover removed.

Insert, as shown, a shim (0.25 mm [0.010 in]) into the gear teeth mesh between the adjustable idler gear and the injector camshaft gear. The shim is inserted on the load side of the gear teeth.

Insert, as shown, a shim (0.25 mm [0.010 in]) into the gear teeth mesh between the adjustable idler and the lower non-scissor idler gear. The shim is inserted on the load side of the gear teeth.

Use hand pressure, only, to move the adjustable idler gear so there is no gap between the teeth and either side of the shims.

Both of the camshaft gears will rotate slightly on the camshafts during this step.

Slight drag will be felt on the shim while pulling the shim in and out.

While holding the adjustable idler gear in position, tighten the adjustable idler gear mounting capscrews.

Remove the feeler gauge.

CAUTION  Make sure all the scissor gear screws are tightened to the proper torque so that they do not back out during engine operation. Severe engine damage can occur.

Load the injector camshaft scissor gear by tightening all of the gear screws.

The valve camshaft gear will rotate slightly on the valve camshaft during this step.

Tighten the injector camshaft scissor gear retaining capscrew.

Loosen the capscrew 360 degrees and tighten again using the toruqe-plus-angle method.

Use hand pressure only to rotate the injector camshaft gear clockwise until the gear train backlash is taken up. Obtain tooth-to-tooth contact between the crankshaft gear and the injector camshaft gear.

Tighten the injector camshaft non-scissor gear retaining capscrew.

Loosen the capscrew 360 degrees and tighten again using the toruqe-plus-angle method.

Tighten the valve camshaft scissor gear retaining capscrew.

Use hand pressure, only, to rotate the valve camshaft gear counterclockwise until the backlash between the injector camshaft gear is taken up. Obtain tooth-to-tooth contact between the injector camshaft gear and the valve camshaft gear.

Tighten the valve camshaft non-scissor gear retaining capscrew.

Coat the entire gear train with clean 15W-40 oil.

Use the access hole in the lower gear cover to lubricate the lower idler gear and crankshaft.

Remove the injector and valve camshaft timing wedges.

A sudden jerking motion upwards is the most effective way to remove wedges.

Remove the crankshaft locking pin.

Install the upper gear cover.Refer to Procedure 001-079 (Gear Cover, Upper) in Section 1.

Install the lower gear cover.Refer to Procedure 001-080 (Gear Cover, Lower) in Section 1.

Install the rocker lever shafts.Refer to Procedure 003-009 (Rocker Lever Assembly) in Section 3.

Install and connect the engine brake wiring harness.Refer to Procedure 020-015 (Engine Brake Wiring Harness) in Section 20.

Install the rocker lever cover and gasket.Refer to Procedure 003-011 (Rocker Lever Cover) in Section 3.

If coolant, oil, excessive fuel, or excessive black smoke, has entered the exhaust system, the aftertreatment system must be inspected.Refer to Procedure 014-013 (Aftertreatment Testing) in Section 14.

Operate the engine and check for leaks.