Jeep CJ/Scrambler 1971-1986 Repair Guide

Camshaft

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REMOVAL & INSTALLATION



See Figures 1, 2, 3, 4, 5 and 6

Caution must be taken when performing this procedure. Camshaft bearings are coated with a material, which can be damaged by scraping the cam lobes across the bearing.

4-134 Engine
  1. Remove the engine.
  2.  
  3. Remove the exhaust manifold.
  4.  
  5. Remove the oil pump and the distributor.
  6.  
  7. Remove the crankshaft pulley.
  8.  
  9. Remove the cylinder head.
  10.  
  11. Remove the exhaust valves.
  12.  
  13. Remove the timing gear cover and the crankshaft and camshaft timing gears.
  14.  
  15. Remove the front end plate.
  16.  
  17. Push the lifters into the cylinder block as far as possible so that the ends of the lifters are not in contact with the camshaft.
  18.  
  19. Secure each tappet in the raised position by installing a clip type clothes pin on the shank of each tappet or tie them up in the plate and spacer.
  20.  
  21. Remove the crankshaft thrust plate attaching screws. Remove the camshaft thrust plate and spacer.
  22.  
  23. Pull the camshaft forward out of the cylinder block being careful to prevent damage to the camshaft bearing surfaces.
  24.  

To install:
  1. Slide the camshaft into the cylinder block being careful to prevent damage to the camshaft bearing surfaces.
  2.  
  3. Install the crankshaft thrust plate attaching screws. Install the camshaft thrust plate and spacer.
  4.  
  5. Remove the clothes pins.
  6.  
  7. Install the front end plate.
  8.  
  9. Install the timing gear cover and the crankshaft and camshaft timing gears.
  10.  
  11. Install the exhaust valves.
  12.  
  13. Install the cylinder head.
  14.  
  15. Install the crankshaft pulley.
  16.  
  17. Install the oil pump and the distributor.
  18.  
  19. Install the exhaust manifold.
  20.  
  21. Install the engine.
  22.  



Click image to see an enlarged view

Fig. Fig. 1: Camshaft and related components from the 4-134 engine

4-150 Engine

CAUTION
To remove perform this procedure the air conditioning system must be discharged. Mishandling of refrigerant gas can cause severe personal injury! If you are not completely familiar with the handling of refrigerant systems, have the system discharged by someone who is.

  1. Disconnect the battery ground.
  2.  
  3. Drain the cooling system.
  4.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by the ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Remove the radiator, discharge the refrigerant system (See General Information & Maintenance ) and remove the condenser.
  2.  
  3. Remove the fuel pump.
  4.  
  5. Matchmark the distributor and engine for installation. Note the rotor position by marking it on the distributor body. Unbolt and remove the distributor and wires.
  6.  
  7. Remove the rocker arm cover.
  8.  
  9. Remove the rocker arm assemblies.
  10.  
  11. Remove the pushrods.
  12.  

Keep everything in order for installation.

  1. Using a tool J-21884, or equivalent, remove the hydraulic lifters.
  2.  
  3. Remove the pulley, vibration damper and timing case cover. Remove the crankshaft oil slinger.
  4.  

If the camshaft sprocket appears to have been rubbing against the cover, check the oil pressure relief holes in the rear cam journal for debris.

  1. Remove the timing chain and sprockets.
  2.  
  3. Slide the camshaft from the engine.
  4.  
  5. Inspect all parts for wear and damage. Lubricate all moving parts with engine oil supplement.
  6.  

To install:
  1. Slide the camshaft into the engine, carefully, to avoid damage to the bearing surfaces.
  2.  
  3. Install the timing chain and sprockets. Make sure that all camshaft timing marks align. Torque the camshaft sprocket bolt to 50 ft. lbs. on 1984-86 models.
  4.  
  5. Install the timing case cover.
  6.  
  7. Using a tool J-21884, or equivalent, install the hydraulic lifters.
  8.  
  9. Install the pushrods.
  10.  
  11. Install the rocker arm assemblies.
  12.  
  13. Install the rocker arm cover.
  14.  
  15. Install the distributor and wires. When installing the distributor, make sure that all matchmarks align. It may be necessary to rotate the oil pump drive tang with a long-bladed screwdriver to facilitate installation of the distributor.
  16.  

If the distributor is not installed correctly, or removed later, the complete installation procedure must be done again.

  1. Install the fuel pump.
  2.  
  3. Install the radiator.
  4.  
  5. Install the condenser and evacuate and charge the refrigerant system. (See General Information & Maintenance ).
  6.  
  7. Fill the cooling system.
  8.  
  9. Connect the battery ground.
  10.  



Click image to see an enlarged view

Fig. Fig. 2: Using a special tool to remove the lifter from the 4-150 engine



Click image to see an enlarged view

Fig. Fig. 3: Pull the camshaft out from the front of the block, be careful not to damage the bearings

4-151 Engine
  1. Remove the air cleaner.
  2.  
  3. Drain the cooling system.
  4.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by the ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Remove the timing gear cover.
  2.  
  3. Disconnect the radiator hoses at the radiator. Remove the radiator.
  4.  
  5. Remove the two camshaft thrust plate screws through the holes in the camshaft gear.
  6.  
  7. Remove the tappets.
  8.  
  9. Remove the distributor, oil pump drive and fuel pump.
  10.  
  11. Remove the camshaft and gear assembly by pulling out through front of the block. Support the shaft carefully when removing it to prevent damaging the camshaft bearings.
  12.  

To install:
  1. Thoroughly coat the camshaft journals with a high quality engine oil supplement such as STP or its equivalent.
  2.  
  3. Install the camshaft assembly in engine block. Use care to prevent damaging the bearings or the camshaft.
  4.  
  5. Turn the crankshaft and camshaft so that the valve timing marks on the gear teeth are aligned. The engine is now in number four cylinder firing position. Install the camshaft thrust plate-to-block screws and tighten to 75 inch lbs.
  6.  
  7. Install the timing gear cover and gasket.
  8.  
  9. Line up the keyway in the hub with the key on crankshaft and slide the hub onto the shaft. Install the center bolt and tighten to 160 ft. lbs.
  10.  
  11. Install the valve tappets, pushrods, pushrod cover, oil pump shaft and gear assembly and the fuel pump. Install the distributor according to the following procedure:
    1. Turn the crankshaft 360° to the firing position of the number one cylinder (number one exhaust and intake valve tappets both on the base circle or "heel'' of the camshaft and the timing notch on the vibration damper is indexed with the top dead center mark TDC on the timing degree scale).
    2.  
    3. Install the distributor and align the shaft so that the rotor arm points toward the number one cylinder spark plug contact.
    4.  

  12.  
  13. Install the rocker arms and pivot balls over the pushrods. With the tappets on the base circle (heel) of camshaft, tighten the rocker arm capscrews to 20 ft. lbs. Do not overtighten.
  14.  
  15. Install the cylinder head cover.
  16.  
  17. Install the intake manifold.
  18.  
  19. Install the radiator and lower radiator hose.
  20.  
  21. Install the belt, fan and shroud. Tighten the fan bolts to 18 ft. lbs.
  22.  
  23. Install the upper radiator hose.
  24.  
  25. Tighten the belts.
  26.  

6-225 Engine
  1. Remove the engine.
  2.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by the ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Remove the intake manifold and carburetor assembly.
  2.  
  3. Remove the distributor.
  4.  
  5. Remove the fuel pump.
  6.  
  7. Remove the alternator, drive belts, cooling fan, fan pulley and water pump.
  8.  
  9. Remove the crankshaft pulley and the vibration damper.
  10.  
  11. Remove the oil pump.
  12.  
  13. Remove the timing chain cover.
  14.  
  15. Remove the timing chain and the camshaft sprocket, along with the distributor drive gear and the fuel pump eccentric.
  16.  
  17. Remove the rocker arm assemblies.
  18.  

The pushrods need not be removed. But if they are, be sure that they are replaced in their original positions.

  1. Lift the tappets up so that they are not in contact with the camshaft. Use wire clips or clip type pins to hold the tappets up.
  2.  
  3. Carefully guide the camshaft forward out of the engine. Avoid marring the bearing surfaces.
  4.  

To install:
  1. Coat all moving parts with an engine oil supplement, such as STP or its equivalent.
  2.  
  3. Slide the camshaft, carefully, into position. Avoid marring the bearing surfaces.
  4.  
  5. Drop the tappets back onto the camshaft.
  6.  
  7. Install the rocker arm assemblies.
  8.  
  9. Install the timing chain and the camshaft sprocket, along with the distributor drive gear and the fuel pump eccentric.
  10.  
  11. Install the timing chain cover.
  12.  
  13. Install the oil pump.
  14.  
  15. Install the crankshaft pulley and the vibration damper.
  16.  
  17. Install the alternator, drive belts, cooling fan, fan pulley and water pump.
  18.  
  19. Install the fuel pump.
  20.  
  21. Install the distributor.
  22.  
  23. Install the intake manifold and carburetor assembly.
  24.  
  25. Install the engine.
  26.  



Click image to see an enlarged view

Fig. Fig. 4: Timing component view on the 6-225 engine

6-232 and 6-258 Engines
  1. Drain the cooling system and remove the radiator. With air conditioning, remove the condenser and receiver assembly as a unit, without disconnecting any lines or discharging the system.
  2.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by the ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Remove the valve cover and gasket, the rocker assemblies, pushrods, cylinder head and gasket and the lifters.
  2.  

The valve train components must be replaced in their original locations.

  1. Remove the drive belts, cooling fan, fan hub assembly, vibration damper and the timing chain cover.
  2.  
  3. Remove the fuel pump and distributor assembly, including the spark plug wires.
  4.  
  5. Rotate the crankshaft until the timing mark of the crankshaft sprocket is adjacent to, and on a center line with, the timing mark of the camshaft sprocket.
  6.  
  7. Remove the crankshaft sprocket, camshaft sprocket, and the timing chain as an assembly.
  8.  
  9. Remove the front bumper or grille as required and carefully slide out the camshaft.
  10.  

To install:
  1. Coat all parts with engine oil supplement.
  2.  
  3. Slide the camshaft into place.
  4.  
  5. Install the front bumper and/or grille.
  6.  
  7. Install the crankshaft sprocket, camshaft sprocket, and the timing chain as an assembly.
  8.  
  9. Rotate the crankshaft until the timing mark of the crankshaft sprocket is adjacent to, and on a center line with, the timing mark of the camshaft sprocket.
  10.  
  11. Install the fuel pump and distributor assembly, including the spark plug wires.
  12.  
  13. Install the drive belts.
  14.  
  15. Install the cooling fan and fan hub assembly.
  16.  
  17. Install the vibration damper.
  18.  
  19. Install the cylinder head and gasket and the lifters.
  20.  
  21. Install the rocker assemblies and pushrods.
  22.  
  23. Install the valve cover and gasket.
  24.  
  25. Install the the timing chain cover.
  26.  
  27. With air conditioning, install the condenser and receiver.
  28.  

The valve train components must be replaced in their original locations.

  1. Fill the cooling system and install the radiator.
  2.  



Click image to see an enlarged view

Fig. Fig. 5: Camshaft and sprocket as used on the 8-304 engine



Click image to see an enlarged view

Fig. Fig. 6: Camshaft lobe measurement positions

8-304 Engines
  1. Disconnect the battery cables.
  2.  
  3. Drain the radiator and both banks of the block. Remove the lower hose at the radiator, the by-pass hose at the pump, the thermostat housing and the radiator. With air conditioning, remove the condenser and receiver assembly as a unit, without disconnecting any lines or discharging the system.
  4.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by the ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Remove the distributor, all wires, and the coil from the manifold.
  2.  
  3. Remove the intake manifold as an assembly.
  4.  
  5. Remove the valve covers, rocker arms and pushrods.
  6.  
  7. Remove the lifters.
  8.  

The valve train components must be replaced in their original locations.

  1. Remove the cooling fan and hub assembly, fuel pump, and heater hose at the water pump.
  2.  
  3. Remove the alternator and bracket as an assembly. Just move it aside, do not disconnect the wiring.
  4.  
  5. Remove the crankshaft pulley and the damper. Remove the lower radiator hose at the water pump.
  6.  
  7. Remove the timing chain cover.
  8.  
  9. Remove the distributor/oil pump drive gear, fuel pump eccentric, sprockets and the timing chain.
  10.  
  11. Remove the grille.
  12.  
  13. Remove the camshaft carefully by sliding it forward out of the engine.
  14.  

To install:
  1. Coat all parts with engine oil supplement.
  2.  
  3. Slide the camshaft, carefully, into the engine.
  4.  
  5. Install the grille.
  6.  
  7. Install the distributor/oil pump drive gear, fuel pump eccentric, sprockets and the timing chain.
  8.  
  9. Install the timing chain cover.
  10.  
  11. Install the crankshaft pulley and the damper.
  12.  
  13. Install the lower radiator hose at the water pump.
  14.  
  15. Install the alternator and bracket as an assembly.
  16.  
  17. Install the cooling fan and hub assembly.
  18.  
  19. Install the fuel pump.
  20.  
  21. Install the heater hose at the water pump.
  22.  
  23. Install the lifters.
  24.  

The valve train components must be replaced in their original locations.

  1. Install the valve covers, rocker arms and pushrods.
  2.  
  3. Install the intake manifold as an assembly.
  4.  
  5. Install the distributor, all wires, and the coil on the manifold.
  6.  
  7. Install the radiator.
  8.  
  9. With air conditioning, install the condenser and receiver assembly.
  10.  
  11. Install the thermostat and housing.
  12.  
  13. Install the by-pass hose at the pump.
  14.  
  15. Install the lower hose at the radiator.
  16.  
  17. Fill the cooling system.
  18.  
  19. Connect the battery cables.
  20.  

CHECKING CAMSHAFT



Camshaft Lobe Lift

Check the lift of each lobe in consecutive order and make a note of the reading.

  1. Remove the fresh air inlet tube and the air cleaner. Remove the heater hose and crankcase ventilation hoses. Remove valve rocker arm cover(s).
  2.  
  3. Remove the rocker arm stud nut or fulcrum bolts, fulcrum seat and rocker arm.
  4.  
  5. Make sure the pushrod is in the valve tappet socket. Install a dial indicator so that the actuating point of the indicator is in the pushrod socket (or the indicator ball socket adaptor is on the end of the pushrod) and in the same plane as the push rod movement.
  6.  
  7. Install an auxiliary starter switch. Crank the engine with the ignition switch off. Turn the crankshaft over until the tappet is on the base circle of the camshaft lobe. At this position, the pushrod will be in its lowest position.
  8.  
  9. Zero the dial indicator. Continue to rotate the crankshaft slowly until the pushrod is in the fully raised position.
  10.  
  11. Compare the total lift recorded on the dial indicator with the specification shown on the Camshaft Specification chart.
  12.  

To check the accuracy of the original indicator reading, continue to rotate the crankshaft until the indicator reads zero. If the left on any lobe is below specified wear limits listed, the camshaft and the valve tappet operating on the worn lobe(s) must be replaced.

  1. Install the dial indicator and auxiliary starter switch.
  2.  
  3. Install the rocker arm, fulcrum seat and stud nut or fulcrum bolts. Check the valve clearance. Adjust if required (refer to procedure in this section).
  4.  
  5. Install the valve rocker arm cover(s) and the air cleaner.
  6.  

Camshaft End Play

On engines with an aluminum or nylon camshaft sprocket, prying against the sprocket, with the valve train load on the camshaft, can break or damage the sprocket. Therefore, the rocker arm adjusting nuts must be backed off, or the rocker arm and shaft assembly must be loosened sufficiently to free the camshaft. After checking the camshaft end play, check the valve clearance. Adjust if required (refer to procedure in this section).

  1. Push the camshaft toward the rear of the engine. Install a dial indicator so that the indicator point is on the camshaft sprocket attaching screw.
  2.  
  3. Zero the dial indicator. Position a prybar between the camshaft gear and the block. Pull the camshaft forward and release it. Compare the dial indicator reading with the specifications.
  4.  
  5. If the end play is excessive, check the spacer for correct installation before it is removed. If the spacer is correctly installed, replace the thrust plate.
  6.  
  7. Remove the dial indicator.
  8.  

CAMSHAFT BEARING REPLACEMENT



  1. Remove the engine following the procedures in this section and install it on a work stand.
  2.  
  3. Remove the camshaft, flywheel and crankshaft, following the appropriate procedures. Push the pistons to the top of the cylinder.
  4.  
  5. Remove the camshaft rear bearing bore plug. Remove the camshaft bearings with a bearing removal tool.
  6.  
  7. Select the proper size expanding collet and back-up nut and assemble on the mandrel. With the expanding collet collapsed, install the collet assembly in the camshaft bearing and tighten the back-up nut on the expanding mandrel until the collet fits the camshaft bearing.
  8.  
  9. Assemble the puller screw and extension (if necessary) and install on the expanding mandrel. Wrap a cloth around the threads of the puller screw to protect the front bearing or journal. Tighten the pulling nut against the thrust bearing and pulling plate to remove the camshaft bearing. Be sure to hold a wrench on the end of the puller screw to prevent it from turning.
  10.  
  11. To remove the front bearing, install the puller from the rear of the cylinder block.
  12.  
  13. Position the new bearings at the bearing bores, and press them in place. Be sure to center the pulling plate and puller screw to avoid damage to the bearing. Failure to use the correct expanding collet can cause severe bearing damage. Align the oil holes in the bearings with the oil holes in the cylinder block before pressing bearings into place.
  14.  
  15. Install the camshaft rear bearing bore plug.
  16.  
  17. Install the camshaft, crankshaft, flywheel and related parts, following the appropriate procedures.
  18.  
  19. Install the engine in the truck, following procedures described earlier in this section.
  20.  

 
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