Jeep Wrangler/YJ 1987-1995 Repair Guide

Camshaft and Bearings

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REMOVAL & INSTALLATION



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

2.5L Engine

See Figures 1, 2, 3 and 4



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Fig. Fig. 1: Camshaft removal-2.5L engine



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Fig. Fig. 2: Oil pump gear slot alignment-2.5L engine



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Fig. Fig. 3: Distributor rotor pre-positioning-2.5L engine



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Fig. Fig. 4: Correct rotor positioning-2.5L engine


CAUTION
To perform this procedure, the air conditioning system must be discharged. Mishandling of refrigerant gas can cause severe personal injury! Unless you have an approved recovery/recycling station and are thoroughly familiar with the handling of refrigerant systems, have the system discharged by a qualified individual.

  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 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 tool J-21884 or equivalent, as shown, 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 80 ft. lbs. (108 Nm).
  4.  
  5. Install the timing case cover.
  6.  
  7. Using 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.  

Position the engine at the number 1 cylinder TDC location. Rotate the gear slot on the oil pump shaft to a point slightly past the 3 o'clock position. Install the distributor with the rotor at the 5 o'clock position. When fully engaged, the rotor should be at the 6 o'clock position.

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.  

4.0L and 4.2L Engines

See Figure 1

  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 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.  

INSPECTION



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 and adjust if necessary (refer to the procedure in this section).
  4.  
  5. Install the valve rocker arm cover(s) and the air cleaner.
  6.  

Camshaft End-Play

Camshaft end-play is maintained by the load placed on the camshaft by the oil pump and distributor drive gear. The helical cut of the gear holds the camshaft sprocket thrust face against the cylinder block face.

BEARING REPLACEMENT



The camshaft rotates within the four steel-shelled, babbitt-lined bearings that are pressed into the cylinder block and then line reamed. The camshaft bearing bores and bearing diameters are not the same size. They are stepped down to 0.010 inch (0.254 mm) increments from the front bearing (largest) to the rear bearing (smallest). This permits easier removal and installation of the camshaft. The camshaft bearings are pressure lubricated.

It is not advisable to attempt to replace camshaft bearings unless special removal and installation tools are available.

  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. Take out the camshaft bearings with a bearing removal tool.
  6.  
  7. Select the proper size expanding collet and back-up nut, and assemble them 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 vehicle, following procedures described earlier in this section.
  20.  

 
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