Chrysler Caravan/Voyager/Town n Country 1984-1995

Pistons and Connecting Rods

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See Figures 1 through 11



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Fig. Fig. 1: Cylinder bore ridge



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Fig. Fig. 2: Use lengths of rubber tubing to protect the crankshaft journal and cylinder linings during piston and rod removal and installation



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Fig. Fig. 3: Carefully tap the piston out of the bore using a wooden dowel



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Fig. Fig. 4: Piston ring positioning



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Fig. Fig. 5: Check the piston ring side clearance



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Fig. Fig. 6: Check the piston ring end-gap



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Fig. Fig. 7: Piston installation



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Fig. Fig. 8: Loosening the connecting rod bearing cap nuts



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Fig. Fig. 9: Loosen the connecting rod nuts enough to protect the bolt threads, then tap lightly to break the cap loose



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Fig. Fig. 10: The connecting rod bearing cap and bearing removed from the connecting rod



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Fig. Fig. 11: Removing the bearing from the connecting rod bearing cap

REMOVAL



The following procedures are performed with the engine removed from vehicle.

  1. Remove the engine from the vehicle.
  2.  
  3. Remove the timing case cover, timing belt or chain, and sprockets/gears.
  4.  
  5. Remove the intake manifold.
  6.  
  7. Remove the cylinder head from engine.
  8.  
  9. Remove the engine oil pan.
  10.  
  11. Remove the oil pump.
  12.  
  13. Remove the balance shaft carrier (2.5L engines).
  14.  

Because the top piston ring does not travel to the very top of the cylinder bore, a ridge is built up between the end of the travel and the top of the cylinder walls. Pushing the piston and connecting rod assembly past the ridge is difficult and may cause damage to the piston. If new rings are installed and the ridge has not been removed, ring breakage and piston damage can occur. If you are going to use a machine shop's services for honing or boring, consult with them before removing the ridge.

  1. Turn the crankshaft to position the piston at the bottom of the cylinder bore. Cover the top of the piston with a rag. Install a ridge reamer in the bore and follow the manufacturer's instructions to remove the ridge. Use caution, avoid cutting too deeply. Remove the rag and cuttings from the top of the piston. Remove the ridge from all cylinders.
  2.  
  3. Turn the crankshaft until the connecting rod is at the bottom of travel.
  4.  
  5. Number all connecting rod caps if not already labeled to aid during assembly. Remove connecting rod bearing cap nuts and remove caps. Keep all parts separated.
  6.  
  7. Take 2 pieces of rubber tubing and cover the rod bolts to prevent cylinder wall scoring.
  8.  
  9. Before removing the piston assembly from cylinder bore scribe a mark indicating front position, or take notice of manufacturer identification mark. Using a wooden hammer handle, carefully tap piston assembly away from crankshaft and remove from cylinder block. Care should be taken not to damage crankshaft connecting rod journals or threads on connecting rod cap bolts.
  10.  
  11. Remove all the pistons from cylinder block in similar fashion.
  12.  

It is not necessary to remove the crankshaft from cylinder block for piston service. If crankshaft service is necessary, refer to the crankshaft procedures in this section.

CLEANING & INSPECTION



See Figures 12, 13, 14, 15 and 16



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Fig. Fig. 12: Use a ring expander tool to remove the piston rings



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Fig. Fig. 13: Clean the piston grooves using a ring groove cleaner



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Fig. Fig. 14: You can use a piece of an old ring to clean the ring grooves, be careful the ring is sharp



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Fig. Fig. 15: An telescoping gauge may be used to measure the cylinder bore diameter



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Fig. Fig. 16: Measure the piston's outer diameter using a micrometer

  1. Use a piston ring expander and remove the rings from the piston.
  2.  
  3. Clean the ring grooves using an appropriate cleaning tool, exercise care to avoid cutting too deeply.
  4.  
  5. Clean all varnish and carbon from the piston with a safe solvent. Do not use a wire brush or caustic solution on the pistons.
  6.  
  7. Inspect the pistons for scuffing, scoring, cracks, pitting or excessive ring groove wear. If wear is evident, the piston must be replaced.
  8.  
  9. Have the piston and connecting rod assembly checked by a machine shop for correct alignment, piston pin wear and piston diameter. If the piston has collapsed it will have to be replaced or knurled to restore original diameter. Connecting rod bushing replacement, piston pin fitting and piston changing can be handled by the machine shop.
  10.  
  11. Check the cylinder bore diameter and cylinder bore for wear using a telescoping gauge at 3 different levels. Cylinder bore out of round: 0.0020 in. (0.05mm) maximum. Cylinder bore taper: 0.005 in. (0.13mm) maximum. Refer to the general engine specification chart for the cylinder bore specification.
  12.  
  13. Check piston dimensions. Measure approximately 0.078 in. (2mm) above the bottom of the piston skirt and across the thrust face. Refer to the piston and ring specification chart for the piston diameter.
  14.  
  15. After recording cylinder bore measurement and piston diameter, subtract the low reading. The difference is the piston-to-cylinder wall clearance: 0.0008-0.0016 in. (0.02-0.04mm).
  16.  
  17. Check piston ring gap using a piston to position the ring at least 0.62 in. (16mm) from the bottom of cylinder bore. Measure clearance using a feeler gauge. Refer to the piston and rings specification chart.
  18.  
  19. Check the ring-to-piston ring groove clearance using a feeler gauge.
  20.  
  21. Check the ring groove by rolling the new piston ring around the groove to check for burrs or carbon deposits. If any are found, remove with a fine file.
  22.  
  23. If all clearances and measurements are within specifications, honing or glaze breaking the cylinder bore is all that is required.
  24.  

INSTALLATION



See Figure 17

  1. Start with the oil ring expander in the lower oil ring groove.
  2.  
  3. Install one oil rail at bottom of the oil ring expander and the other at top. The oil rails must be spaced 180° apart from each other.
  4.  
  5. Using the ring expander install the intermediate piston ring.
  6.  



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Fig. Fig. 17: Installing the piston into the block using a ring compressor and the handle of a hammer

  1. Install the upper piston ring using the ring expander.
  2.  

Generally marks on the upper and intermediate piston rings must point toward the crown of piston. Consult the illustration with piston ring set instruction sheet for ring positioning.

  1. Install a ring compressor, then insert the piston and rod assembly into the engine with the mark previously made, or the labeled mark on the piston head, toward the timing belt/chain end of the cylinder block.
  2.  
  3. Rotate the crankshaft so that the connecting rod journal is on center of cylinder bore. Install a new connecting rod bearing in connecting rod and cap. Check the connecting rod bearing oil clearance using Plastigage®. Follow the manufacturer procedures. Refer to the crankshaft and connecting rod specification chart.
  4.  
  5. Tighten the connecting rod cap nuts to specification. Refer to the torque specification chart later in this section for the proper torque values.
  6.  
  7. Install the remaining piston and rod assemblies.
  8.  
  9. Using a feeler gauge, check connecting rod side clearance.
  10.  
  11. On 2.5L engines, install the balance shaft carrier.
  12.  
  13. Install the oil pump and pick-up.
  14.  
  15. Install the cylinder head.
  16.  
  17. Install the intake manifold.
  18.  
  19. Install the timing chain or belt and the sprockets or gears.
  20.  
  21. Install the timing case cover.
  22.  
  23. Install the engine oil pan.
  24.  
  25. Install the engine in the vehicle.
  26.  

 
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