CAMSHAFT GEAR TRAIN AUXILIARY DRIVE AND CAMSHAFT ASSEMBLIES

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CAMSHAFT GEAR TRAIN

DESCRIPTION
Power necessary to drive the camshafts, and the turbocharger before it becomes free wheeling, is supplied through the gear train at the rear of the engine. Fig. 7-1 shows the gear train before the camshaft drive housing and turbocharger are installed, and Fig. 7-2 shows a cross-section of the gear train. a spring drive gear assembly, and the left and right camshaft drive gears. The spring drive gear assembly is made up of the No. 2 idler gear, a spring assembly, and the turbocharger drive gear.

CAMSHAFT DRIVE GEARS INSTALLATION

1. Install the camshaft drive gear on the stubshaft being sure to position it on the stubshaft so the position markings line up with the markings on the mating parts, as shown in Fig. 7-21.

2. Install counterweight on stubshaft with counterweight to stubshaft marks aligned.

3. Install dowels, dowel retainer plate, and counterweight to stubshaft bolts. Torque bolts to 122 N-m (90 ft-lbs).

4. Install dowel bolts and torque to 22 N-m (17 ft-lbs).

5. Lockwire mounting bolts and dowel bolts in groups of three (two mounting bolts and one dowel bolt).

6. If any gears in the camshaft gear train are replaced or the relationship of the crankshaft to the camshaft has been disturbed, refer to "Exhaust Valve Timing" at the end of this section for information on positioning and marking of gears

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CAMSHAFT DRIVE GEARS REMOVAL

1. Remove the Lockwire and the four bolts holding the counterweight and camshaft drive gear to the stubshaft.

2. Remove the dowel bolts and the retainer plate.

3. The counterweight and camshaft drive gear can now be removed from the stubshaft.

4. Remove the dowels from the counterweight and camshaft drive gear by driving them out from the back side of the gear

SPRING DRIVE GEAR ASSEMBLY

The spring drive gear assembly, Fig. 7-3, consists of the No. 2 idler gear, the turbocharger drive gear, and a spring assembly mounted between the two gears to absorb any torsional vibration which might be transmitted through the gear assembly to the turbocharger. The spring drive gear assembly should be removed as an assembly and then disassembled for inspection

DISASSEMBLY OF SPRING DRIVE GEAR

1. Remove the spring drive gear assembly from the stubshaft and check for any loose gearto-spider bolts. Discard any loose bolts. This is necessary because loose bolts caused by movement of the spiders due to high loads will have damaged threads. Damaged bolts will result in unsatisfactory clamp load.

2. Remove Lockwire and the eight 1/2"-1 3 bolts that hold the turbocharger drive gear to the outer spider.

3. Remove the snap ring near the inner circum-ference of the gear. The turbocharger drive gear can now be separated from the assembly.

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4. Next remove the spring assembly from the idler gear by removing the 5/8"-11 bolts and the 1/2" dowels from the idler gear.

5. It should not be necessary to further disassemble the spring drive gear assembly. The spiders, springs, and spring seats making up the spring assembly do not require any routine type of maintenance. If the spring drive gear assembly is found to be defective, it should be replaced with a qualified assembly.

WARNING: Any attempt to disassemble the spring assembly with the use of vises, clamps, rams, or pinch bars can be extremely hazardous and is not recommended.

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INSPECTION Inspect the gear teeth for fatigue indications, cracks, pits, or other evidence of failure. If possible, a magnaflux inspection should be performed on the gears. Inspect the idler gear bearings to see that they are not gouged or damaged in any way. Also check oil holes to see that they are not plugged.

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SPRING DRIVE GEAR ASSEMBLY

1. Thoroughly clean four 5/8"-11 idler to spider mounting bolts to remove all traces of thread lubricant. Use cleaner activator listed in Service Data. Also clean spider bolt holes of lubricant and contaminants, using the same cleaner.

2. Slide spring assembly over the idler gear hub. Apply sealing compound to the 5/8"-11 bolts and install bolts through the idler gear into the inner spider. Torque to 224 N-m (165 ft-lbs). If the same idler gear and spring assembly are used, install the gear to spider dowels to 6.35 mm (1/4") below the surface and stake the dowel holes in three places, 120° apart.

If a new idler gear and spring assembly are being used, drill two holes through the gear web and into the spider. Drill 37.34 mm (1-5/16") deep and line ream the holes to 34.52 mm (1-9/32") deep x 12.662 mm plus 0.013 mm minus 0.000 mm (.4985" plus .005" minus .000"). Locate the holes 100.00 mm ± 0.08 mm (3.937" ± .003") above and below the idler gear centerline and in line with two gear mounting bolt holes. Drive two dowels to 6.35 mm (1/4") below the surface and stake the holes at three places, 120° apart.

3. Install the turbocharger drive gear on the idler gear hub and install the snap ring in the idler gear hub groove.

4. Apply thread lubricant to the bolt threads and washer surfaces and install the eight 1/2"-13 x 1-1/4" bolts with hardened washers (replace 1-1/8" bolts used on early models and add washers) through the turbocharger drive gear into the outer spider. Torque bolts to 111 N-m (82 ft-lbs) and lockwire the bolt heads

SPRING DRIVE GEAR INSTALLATION

1. Place the spring drive gear assembly on the idler gear stubshaft being sure the tooth position marks are aligned as shown in Fig. 7-21.

2. If a new gear is used, refer to "Exhaust Valve Timing" at the end of this section for information on positioning and marking of gears. Timing procedures are not required if camshaft and crankshaft positions have not been disturbed

NO. 1 IDLER GEAR REMOVAL

1. Remove the four bolts and washers holding the thrust plate and idler gear.

2. Remove the thrust plate and idler gear from the stubshaft.

IDLER GEAR STUBSHAFT ASSEMBLY REMOVAL

1. After the spring drive gear assembly, the No. 1 idler gear and the attached oil lines have been removed, the stubshaft assembly can be taken off.

2. Remove the lockwire, dowel bolts, and the locating dowels.

3. Remove the mounting bolts and stubshaft assembly.

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IDLER GEAR STUBSHAFT INSPECTION

1. Check that oil passages are not plugged.

2. Check alignment of oil holes in upper stubshaft sleeve with holes in stubshaft. Inspect sleeve for nicks or gouges.

3. Inspect upper stubshaft seal and replace, if necessary.

4. Check bearing on lower stubshaft and sleeve on upper stubshaft to see that they are not gouged or damaged in any way.

NO. 1 STUBSHAFT BEARING REPLACEMENT

1. Remove pressfit bearing from stubshaft by heating bearing until it can be removed.

2. Install new bearing by heating bearing in oil to 149°-163° C (300°-325° F) and pressing on stubshaft. Make certain that oil hole through bearing is at the 12 o'clock position.

NO. 2 STUBSHAFT SLEEVE REPLACEMENT

1. Remove 3/8" dowel which pins sleeve to stubshaft. Heat sleeve until it can be removed from stubshaft.

2. Install new sleeve by heating sleeve in oil to 260° C (500° F) and pressing on stubshaft. Oil holes in sleeve should be aligned to within 1/32" of oil passages in stubshaft. Install new dowel.

INSTALLATION If a new stubshaft assembly is to be applied, see "Camshaft Gear Train Assembly" for installation procedure. If the stubshaft assembly that was removed from the engine is to be re-used, see the following installation procedure.

1. Attach the stubshaft assembly to the crankcase with the three vertically centered mounting bolts, and finger tighten.

2. Apply the lower idler gear to the stubshaft assembly to mesh with the crankshaft gear.

3. Place a feeler gauge between the lower idler and crankshaft gear teeth, and check the backlash. Backlash limits are in the Service Data.

4. If necessary, reposition the stubshaft assembly until the allowable backlash is obtained.

5. Apply the remaining stubshaft assembly mounting bolts, and torque all bolts.

6. Install dowels and dowel bolts, and lockwire all bolts.

7. Apply the oil lines to the stubshaft bracket.

CRANKSHAFT GEAR REMOVAL

l. Remove the crankshaft gear from crankshaft.

2. The oil slinger can be removed from the crankshaft gear by removing the oil slinger to crankshaft gear bolts.

STUBSHAFT BRACKET APPLICATION

1. Inspect the crankcase end plate for any burrs or damaged areas.

2. Clean any dirt or debris from the holes in the end plate or the end plate surface.

3. Wipe the crankshaft gear teeth clean, insert the coupling bolts in the gear from the back side and install it in its proper position on the crankshaft, as shown in Fig. 7-21. Secure the crankshaft gear with two nuts, moderately tightened.

If a new gear is used, refer to "Exhaust Valve Timing" at the end of this section for information on positioning and marking of gears. Timing procedures are not required if camshaft positions have not been disturbed.

4. Inspect the stubshaft bracket rear surface for burrs and wipe clean, making sure all oil passages are clean and free of dirt.

5. Install two temporary locating pins, Fig. 7-5, into the idler gear stubshaft bracket mounting holes in the crankcase end plate.

6. Install the stubshaft bracket in position and apply the three vertically centered 1/2"-20 mounting bolts with hardened washers. Finger tighten the mounting bolts.

7. Apply the idler gear gauge (File 768) to the No. 1 idler gear stubshaft, Fig. 7-6, and place a feeler gauge between the idler gear gauge teeth and the crankshaft gear teeth to check the gear backlash which is specified in the Service Data at the end of this section.

NOTE: The No. 1 idler gear may be used if a gauge is not available.

8. If the backlash is not within limits specified, gently tap the stubshaft bracket with a brass hammer until it is in position to obtain the proper backlash.

CAUTION: Do not tap on machined surfaces of the stubshaft bracket.

9. When the stubshaft bracket is properly aligned, tighten the bottom bolt to the proper torque and re-check the backlash.

10. Apply an idler gear stubshaft to camshaft stubshaft gauge (File 769), Fig. 7-7, and check the dimension between the No. 2 idler gear stubshaft and the left bank camshaft stubshaft making sure both stubshafts are wiped clean. Gauge must indicate less than 0.005 ".

NOTE: The No. 2 idler gear and left bank camshaft drive gear may be applied and backlash reading taken between No. 2 idler gear and camshaft drive gear if gauge is not available. See Service Data for limits.

Fig. 7-6 - Checking No. 1 Idler Gear To Crankshaft Gear Backlash

11. If the dimension is not within limits, gently tap the stubshaft bracket until it is properly positioned.

CAUTION: Do not tap on machined surfaces of the stubshaft bracket.

12. When the stubshaft bracket is properly positioned, tighten the top and center mounting bolts to the proper torque and recheck the backlash between the idler gear gauge and the crankshaft gear.

13. If the backlash is not within the proper limits, the three vertical mounting bolts must be loosened and Steps 7 thru 12 repeated.

14. Remove the idler gear gauge and apply the remaining stubshaft mounting bolts and washers.

NOTE: One 3/8"-24 bolt is used at the edge of the stubshaft bracket directly below the lube oil manifold connection to the stubshaft bracket.

15. Remove the two temporary locating pins and apply the two mounting bolts and washers. Then tighten all mounting bolts to the proper torque.

16. Ream the two dowel holes with a 0.494" tapered reamer and a 0.4998" ± 0.0002" bottoming reamer while using cutting oil.

NOTE: If dowel holes in idler gear stubshaft bracket do not align with holes in crankcase, drill and ream for oversize dowels as required to produce full circumference fit. See parts catalog for listing of oversize dowels.

17. Use an air hose to blow chips and oil out of the dowel holes.

18. Insert 5/16"-24 bolts approximately 12.70 mm (1/2") into the dowel pins.

19. Place dowels in dowel holes of stubshaft bracket and drive into crankcase end plate.

20. Torque the dowel bolts to 23 N-m (17 ft-lbs) and lockwire all mounting and dowel bolts in groups of three or less.

21. Using a No. 1 stubshaft to No. 2 stubshaft gauge (File 770) check parallelism between the No. 1 and No. 2 stubshafts, Fig. 7-8. Take one indicator reading with gauge as close to the stubshaft bracket as possible and the other reading with gauge near the end of the No. 1 stubshaft. Dial indicator readings must be within 0.004".

NOTE: Parallelism may also be checked by applying both idler gears, then checking gear teeth mesh and taking backlash measurements. See Service Data for backlash limits.

Fig. 7-5 - Checking Parallelism Of No. 1 And No. 2 Stubshafts

22. After a double idler stubshaft bracket has been applied to the crankcase rear end sheet, with all bolts torqued, the assembly should be checked for gaps in excess of .004" which could cause a critical loss of oil pressure. To perform this check, run a .004" feeler gage around the periphery of the bracket. If the feeler gage can be inserted into an oil passage, the bracket must be removed and the cause eliminated.

23. Re-check the dimension between the No. 2 idler stubshaft and the left bank camshaft stubshaft

NO. 1 IDLER GEAR APPLICATION

1. Apply a light coat of lubricating oil to the No. 1 idler gear stubshaft and place the idler gear on the stubshaft so the tooth position marks are aligned as shown in Fig. 7-21.

2. Install the No. 1 idler gear thrust plate, hardened washers, and bolts. Tighten bolts to the proper torque and lockwire in pairs using a crisscross pattern.

3. Use a feeler gauge to check that the No. I idler gear thrust clearance is within the limit specified in the Service Data.

4. Re-check the backlash between the crankshaft gear and the No. 1 idler gear as in Step 7 of "Stubshaft Bracket Application."

CAMSHAFT DRIVE HOUSING APPLICATION

1. Check the camshaft drive housing seal surfaces for burrs and wipe free of dust and dirt.

2. Apply a coat of gasket sealer to the camshaft drive housing. Apply the gasket in sections to the camshaft drive housing being sure the gasket interlocks are joined properly.

3. Apply the camshaft drive housing to crankcase bolts to the housing and wipe the crankcase end plate clean.

4. Trim the rubber crankcase to oil pan gasket extending from the joint at the crankcase end plate and apply Permatex to the joint area.

5. Locate the camshaft drive housing in its proper position and snug down several of the bolts to hold it in place.

6. 7-10, to act as positioning points for a dial indicator.

7. Install the camshaft drive housing alignment gauge (File 771) on the left bank camshaft stubshaft, and sweep the left bank locating pin, Fig. 7-10. The camshaft drive housing is properly aligned when an 0.008"-0.010" reading is obtained on the dial indicator

8. Repeat Step 7 on the right bank camshaft stubshaft.

9. If the housing is not aligned properly, place a wedge (File 772) between the camshaft stubshaft bracket and the housing, and drive the wedge in with a brass hammer.

10. If the dial indicator shows the camshaft drive housing to be properly aligned, torque the mounting bolts to the proper torque, then remove the wedge and recheck the alignment.

11. Ream the two dowel holes in the camshaft drive housing with a 0.494" tapered reamer and a 0.4998" ± 0.0002" bottoming reamer, being sure to use cutting oil.

NOTE: If dowel holes in camshaft drive housing do not align with holes in crankcase, drill and ream for oversize dowels as required to produce full circumference fit. See parts catalog for listing of oversize dowels.

12. Use an air hose to blow chips and oil out of the dowel holes, and insert 5/16'-24 bolts approximately 12.70 mm (1/2") into the dowel pins.

13. Place dowels in dowel holes in the housing, and drive into the crankcase end plate. Remove the dowel bolts.

14. Install the two remaining camshaft drive mounting bolts in the holes next to the dowel pins, and torque to the specified torque.

15. Lockwire the camshaft drive housing upper bolts in three groups of three each, and the two remaining mounting bolts to the bolts previously installed in the end plate for anchoring the lockwire.

16. Install the remaining oil manifold section, being sure to apply the proper gasket between the manifold and crankcase and between the manifold section previously installed and the one being applied. Use locknuts on the bolts connecting the two sections, and lockwire the manifold to crankcase bolts. If the turbocharger filter is not installed at this time, temporary bolts and spacers should be applied to the filter mounting bolts.

17. Install the oil slinger and the oil slinger-to-crankshaft gear bolts.

18. Prior to installation of the oil seal retainer, measure the distance from the inner face of the retainer mounting flange to the inner face of the retainer tapered flange, Fig. 7-2. Then measure the distance from the outer face of the camshaft drive housing to the face of the oil slinger with the crankshaft positioned toward the rear of the engine. The difference between the two measurements should equal the clearance specified in Service Data. If required, add or remove oil slinger shims to obtain proper clearance.

19. If oil retainer has dowels, remove the dowels.

20. Apply oil retainer gasket and oil retainer. Install four equally spaced bolts and washers finger tight.

21. Center the retainer by tapping the OD with a soft-faced hammer until the radial clearance between the retainer ID and the gear sealing surface OD is uniform around the circumference, as measured with a feeler gauge. Refer to Service Data for proper radial clearance.

22. Apply the remainder of the 24 bolts and washers and torque to 41 N-m (30 ft-lbs).

23. Recheck for uniform clearance to ensure that the retainer has not shifted.

24. Apply camshaft drive gears and spring drive gear assembly as previously described

PISTON COOLING FLANGES AND LUBE OIL MANIFOLD APPLICATION

l. If the flanges Governing the piston cooling manifold openings on the crankcase end plate have been removed, install the flange gaskets, flanges, and 3/8"-24 bolts, Fig. 7-9. Torque the bolts to 37 N-m (27 ft-lbs) and lockwire.

2. Assemble the end and center oil manifold sections being sure to install a gasket between them. Use 3/8"-24 bolts with locknuts and tighten to 37 N-m (27 ft-lbs).

3. Install the previously assembled manifold section and the stubshaft to left bank camshaft oil line, Fig. 7-9, being sure to place gaskets under the manifold sections. Tighten the 3/8"-24 bolts to 37 N-m (27 ft-lbs) and lockwire.

NOTE: If the stubshaft to left bank camshaft manifold does not have the pipe plug installed, coat the threads with high tem-perature thread compound and install in the manifold.

4. Install two 1/2"-20 bolts, Fig. 7-9, and tighten to 88 N-m (65 ft-lbs) torque. These bolts will be used for an anchor for lockwiring camshaft drive housing to crankcase bolts.

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AUXILIARY DRIVE ASSEMBLY

DESCRIPTION
The auxiliary drive assembly, Fig. 7-11, is mounted on the turbocharger housing and is driven from the right bank camshaft drive gear.
1. Coupling Flange 4. Oil Slinger 7. Support Housing
2. Dust Shield 5. Mounting Pilot 8. Drain
3. Cover 6. Drive Shaft And Gear 9. Bushing
Fig. 7-11 - Auxiliary Drive Assembly
MAINTENANCE
When new bearings are installed, they are pressed into the support housing and line reamed or bored to the dimension specified in Service Data. After mounting the assembly on the turbocharger housing, the backlash between the gears must be checked and adjusted, if necessary.
Check the backlash with a dial indicator, Fig. 7-12. Attach a small "C" clamp to the coupling flange so that clamp contacts the outer edge of the flange. Position the dial indicator with the contact point touching the "C" clamp. Remove play from gear teeth by turning the coupling flange. Set the dial indicator to zero and move flange in the opposite direction of the previous movement and note reading on dial indicator.
Fig. 7-12 - Checking Auxiliary Drive Gear Backlash
Refer to Service Data for backlash limits. Backlash is adjusted by loosening the turbocharger mounting bolts and repositioning the turbocharger on the camshaft drive housing.
After correct backlash is obtained, the turbocharger mounting bolts are tightened, and the backlash checked to see that it has not changed.

CAMSHAFT ASSEMBLIES

DESCRIPTION
The camshaft assembly, Fig. 7-13, consists of flanged segments, front and rear stubshafts, and a spacer is used on 12, 16, and 20-cylinder engines between the center segments. Each segment spans three (12-cyl.), four (8 & 16-cyl.), and five (20-cyl.) cylinders. Segment flanges are marked as shown in Fig. 7-13 to aid in correct assembly. At each cylinder there are two exhaust cams, one injector cam, and two bearing journals. Two bearing blocks at each cylinder, equipped with steel-backed lead base babbit lined inserts, support the camshaft.

REMOVALThe camshaft may be removed without disturbing the stubshafts by removing the dowel bolts connecting the segment and stubshaft flanges, removing oil lines from segment bearing blocks to rocker arms, and removing rocker arms. Remove segment bearing block caps to allow camshaft removal. If the camshaft is removed for reasons other than bearing replacement, an attempt should be made to retain relative position of the bearing shells on reinstallation of the camshaft. This may be accomplished by immediately replacing caps after camshaft removal, or if the entire block is removed, by inserting block bolts and wiring the free ends of the bolts. It is possible to remove a segment of the 16 and 20-cylinder camshaft without removing the entire camshaft. However, the entire camshaft must be removed on a 12-cylinder engine to change a segment.

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LOCATING TOP DEAD CENTERIf it should become necessary to check the position of the flywheel or the flywheel pointer for top dead center, proceed as follows:

1. Remove an air box handhole cover at the No. 1 cylinder.

2. If necessary, bar the engine to position the No. 1 piston below the cylinder liner ports.

3. Insert a brass "stop-bare (minimum 1/2" hex-agonal or square preferred) of suitable length through the ports of the No. 1 cylinder so that the end of the bar passes through a port on the opposite side of the cylinder, Fig. 7-15.

NOTE: A bar of sufficient length to prevent reapplication of the handhole cover while the bar is in place is recommended. A flag on the end of the bar will caution against inadvertent rotation of the engine with the bar in place.

4. Manually bar the engine slowly in the normal direction of rotation until piston travel is stopped by the bar against the upper surfaces of the cylinder ports, Fig. 7-16.

CAUTION: Use extreme care to avoid excessive force.

5. Mark the position of the flywheel pointer on the flywheel, Fig. 7-17.

6. Manually bar the engine slowly in the opposite direction from normal rotation until piston travel is again stopped by the bar against the upper surfaces of the cylinder ports.

7. Mark the second position of the flywheel pointer on the flywheel, Fig. 7-18.

8. Determine the number of degrees between the two marks on the flywheel. Divide that number by 2. See Fig. 7-19 for a sample calculation.

a. Mark flywheel as indicated in Step 5.

b. Mark flywheel as indicated in Step 7.

c. Determine number of degrees as indicated in Step 8. Divide by 2.

d. Rotate 35'. Pointer should indicate 180'. If it does not, adjust pointer to indicate 180`. 21158

9. Rotate the crankshaft in the normal direction of rotation the exact number of degrees determined in Step 8 above. Remove the brass "stop-bar" from the engine.

10. The pointer should indicate 180° (bottom dead center). If it does not, position the pointer so that it does indicate 180°. The pointer will now indicate top dead center for the No. 1 crankpin when the engine is rotated so that the pointer is at zero degrees (0°)

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CHECKING EXHAUST VALVE TIMING It timing is incorrect, check for:1. Proper installation of camshaft.2. Camshaft gear train correctly timed.3. Excessively worn gears.

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