Chrysler Full-Size Vans 1967-1988 Repair Guide

Crankshaft and Main Bearings

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PRECAUTIONS



Inline 6-Cylinder Engines

The maximum allowable bearing clearance is 0.001" no. 1, no. 2 and no. 4 lower inserts are interchangeable no. 1 upper insert has a chamfer on the tab side for timing chain oiling and is identified by the red mark on the edge of the no. 3 upper and lower inserts are flanged. Bearing caps are not interchangeable and are numbered for correct installation. Maximum end-play is 0.0085". Replace no. 3 (thrust) bearing if end-play exceeds that amount.

V6 and V8 Engines

A Maltese Cross stamped on the engine (except on the 318 and 360) numbering pad indicates that the engine is equipped with a crankshaft which has one or more connecting rods and/or main bearing journal finished 0.001" undersize. The position of the underside journal(s) is stamped on a machine surface of the no. 3 counterweight. The letter R or M signifies whether the undersize journal is a rod or main, and the number following the letter indicates which one it is. A Maltese Cross with an X indicates that all those journals are 0.010" undersize. On the 318 and 360 engines, 0.001" undersize journals are indicated by marks on the no. 8 crankshaft counterweight. If the R or M is followed by an X, all those journals are 0.010" undersize.

Upper and lower bearing inserts are not interchangeable on any of the V8 engines due to oil hole and V-groove in the uppers. On the 318 and 360 cu.in. engine lower bearing halves no. 1, no. 2 and no. 4 are interchangeable; no. 1, no. 2 and no. 4 upper bearing halves are interchangeable. no. 3 bearing is the thrust bearing and no. 5 is the wider rear main bearing. On 400 and 440 cu.in. engines the no. 1, no. 2, no. 4 and no. 5 lower bearing halves are interchangeable; no. 2, no. 4 and no. 5 upper bearing halves are interchangeable no. 1 upper insert has a chamfer on the tab side for timing chain oiling and is identified by the red marking on the edge no. 3 bearing is a thrust bearing and should be replaced if end-play exceeds 0.007".

Remove main bearing caps one at a time and check clearance. Check number of cap for proper location.

On the 400 and 440 cu.in. engines, the rear main bearing lower seal is held in place by a seal retainer. On the 318 and 360 cu.in. engine, the rear main bearing lower seal is held in place by the rear main bearing cap. Note that the oil pump is mounted on this cap and that there is a hollow dowel which must be in place when the cap is installed.

REMOVAL & INSTALLATION



Engine Removed
GASOLINE ENGINES
  1. With the engine removed from the vehicle and placed in a work stand, disconnect the spark plug wires from the spark plugs and remove the wires and bracket assembly from the attaching stud on the valve rocker arm cover(s) if so equipped. Disconnect the coil to distributor high tension lead at the coil. Remove the distributor cap and spark plug wires as an assembly. Remove the spark plugs to allow easy rotation of the crankshaft.
  2.  
  3. Remove the fuel pump and oil filter. Slide the water pump by-pass hose clamp (if so equipped) toward the water pump. Remove the alternator and mounting brackets.
  4.  
  5. Remove the crankshaft pulley from the crankshaft vibration damper. Remove the capscrew and washer from the end of the crankshaft. Install a universal puller on the crankshaft vibration damper and remove the damper.
  6.  
  7. Remove the cylinder front cover and crankshaft gear, refer to Cylinder Front Cover and Timing Chain in this guide.
  8.  
  9. Invert the engine on the work stand. Remove the clutch pressure plate and disc (manual shift transmission). Remove the flywheel and engine rear cover plate. Remove the oil pan and gasket. Remove the oil pump.
  10.  
  11. Make sure all bearing caps (main and connecting rod) are marked so that they can be installed in their original locations. Turn the crankshaft until the connecting rod from which the cap is being removed is down, and remove the bearing cap. Push the connecting rod and piston assembly up into the cylinder. Repeat this procedure until all the connecting rod bearing caps are removed.
  12.  
  13. Remove the main bearing caps.
  14.  
  15. Carefully lift the crankshaft out of the block so that the thrust bearing surfaces are not damaged. Handle the crankshaft with care to avoid possible fracture to the finished surfaces.
  16.  
  17. Remove the rear journal seal from the block and rear main bearing cap.
  18.  
  19. Remove the main bearing inserts from the block and bearing caps.
  20.  
  21. Remove the connecting rod bearing inserts from the connecting rods and caps.
  22.  
  23. If the crankshaft main bearing journals have been refinished to a definite undersize, install the correct undersize bearings. Be sure the bearing inserts and bearing bores are clean. Foreign material under the inserts will distort the bearing and cause a failure.
  24.  
  25. Place the upper main bearing inserts in position in the bores with the tang fitting in the slot. Be sure the oil holes in the bearing inserts are aligned with the oil holes in the cylinder block.
  26.  
  27. Install the lower main bearing inserts in the bearing caps.
  28.  
  29. Clean the rear journal oil seal groove and the mating surfaces of the block and rear main bearing cap.
  30.  
  31. Dip the lip-type seal halves in clean engine oil. Install the seals in the bearing cap and block with the undercut side of the seal toward the front of the engine.
  32.  

This procedure applies only to engines with two piece rear main bearing oil seals. those having one piece seals will be installed after the crankshaft is in place.

  1. Carefully lower the crankshaft into place. Be careful not to damage the bearing surfaces.
  2.  

Refer to Rear Main Oil Seal removal and installation, for special instructions in applying RTV sealer to rear main bearing cup.

  1. Install all the bearing caps except the thrust bearing cap. Be sure the main bearing caps are installed in their original locations. Tighten the bearing cap bolts to specifications.
  2.  
  3. Install the thrust bearing cap with the bolts finger-tight.
  4.  
  5. Pry the crankshaft forward against the thrust surface of the upper half of the bearing.
  6.  
  7. Hold the crankshaft forward and pry the thrust bearing cap to the rear. This will align the thrust surfaces of both halves of the bearing.
  8.  
  9. Retain the forward pressure on the crankshaft. Tighten the cap bolts to specifications.
  10.  
  11. On engines with one piece rear main bearing oil seal, coat a new crankshaft rear oil seal with oil and install using a seal driver. Inspect the seal to be sure it was not damaged during installation.
  12.  
  13. Install new bearing inserts in the connecting rods and caps. Check the clearance of each bearing, following the procedure.
  14.  
  15. After the connecting rod bearings have been fitted, apply a light coat of engine oil to the journals and bearings.
  16.  
  17. Turn the crankshaft throw to the bottom of its stroke. Push the piston all the way down until the rod bearing seats on the crankshaft journal.
  18.  
  19. Install the connecting rod cap. Tighten the nuts to specification.
  20.  
  21. After the piston and connecting rod assemblies have been installed, check the side clearance with a feeler gauge between the connecting rods on each connecting rod crankshaft journal. Refer to Crankshaft and Connecting Rod specifications chart in this guide.
  22.  
  23. Install the timing chain and sprockets or gears, cylinder front cover and crankshaft pulley and adapter, following steps under Cylinder Front Cover and Timing Chain Installation in this guide.
  24.  

DIESEL ENGINES
  1. With the engine on a workstand, remove the front cover and timing gears. Remove the piston and rod assemblies. Identify each one for assembly.
  2.  
  3. Remove the main bearing caps from Nos. 1 and 7 bearings using puller C-3752-D and adapters. Remove the lower bearing inserts.
  4.  
  5. Remove the caps from Nos. 2 through 6 main bearings using the puller and adapters. Remove the lower bearing inserts.
  6.  
  7. Lift out the crankshaft.
  8.  
  9. Remove the upper bearing inserts.
  10.  
  11. Remove the thrust plates from No. 7 insert.
  12.  

Refer to Rear Main Oil Seal removal and installation, for special instructions in applying RTV sealer to rear main bearing cup.

  1. Install all the bearing caps except the thrust bearing cap. Be sure the main bearing caps are installed in their original locations. Tighten the bearing cap bolts to specifications.
  2.  
  3. Install the thrust bearing cap with the bolts finger-tight.
  4.  
  5. Pry the crankshaft forward against the thrust surface of the upper half of the bearing.
  6.  
  7. Hold the crankshaft forward and pry the thrust bearing cap to the rear. This will align the thrust surfaces of both halves of the bearing.
  8.  
  9. Retain the forward pressure on the crankshaft. Tighten the cap bolts to specifications.
  10.  
  11. On engines with one piece rear main bearing oil seal, coat a new crankshaft rear oil seal with oil and install using a seal driver. Inspect the seal to be sure it was not damaged during installation.
  12.  
  13. Install new bearing inserts in the connecting rods and caps. Check the clearance of each bearing, following the procedure.
  14.  
  15. After the connecting rod bearings have been fitted, apply a light coat of engine oil to the journals and bearings.
  16.  
  17. Turn the crankshaft throw to the bottom of its stroke. Push the piston all the way down until the rod bearing seats on the crankshaft journal.
  18.  
  19. Install the connecting rod cap. Tighten the nuts to specification.
  20.  
  21. After the piston and connecting rod assemblies have been installed, check the side clearance with a feeler gauge between the connecting rods on each connecting rod crankshaft journal. Refer to Crankshaft and Connecting Rod specifications chart in this guide.
  22.  
  23. Install the timing chain and sprockets or gears, cylinder front cover and crankshaft pulley and adapter, following steps under Cylinder Front Cover and Timing Chain Installation in this guide.
  24.  

Engine Installed

This won't be possible on all engines or vehicles.

  1. With the oil pan, oil pump and spark plugs removed, remove the cap from the main bearing needing replacement and remove the bearing from the cap.
  2.  
  3. Make a bearing roll-out pin, using a bent cotter pin as shown in the illustration. Install the end of the pin in the oil hole in the crankshaft journal.
  4.  
  5. Rotate the crankshaft clockwise as viewed from the front of the engine. This will roll the upper bearing out of the block.
  6.  
  7. Lube the new upper bearing with clean engine oil and insert the plain (unnotch) end between the crankshaft and the indented or notched side of the block. Roll the bearing into place, making sure that the oil holes are aligned. Remove the roll pin from the oil hole.
  8.  
  9. Lube the new lower bearing and install it in the main bearing cap. Install the main bearing cap onto the block, making sure it is positioned in proper direction with the matchmarks in alignment.
  10.  
  11. Torque the main bearing cap to specification.
  12.  

See Crankshaft Installation for thrust bearing alignment.

CRANKSHAFT CLEANING AND INSPECTION



Handle the crankshaft carefully to avoid damage to the finish surfaces.

  1. Clean the crankshaft with solvent, and blow out all oil passages with compressed air.
  2.  
  3. Use crocus cloth to remove any sharp edges, burrs or other imperfections which might damage the oil seal during installation or cause premature seal wear.
  4.  

Do not use crocus cloth to polish the seal surfaces. A finely polished surface may produce poor sealing or cause premature seal wear.

  1. Inspect the main and connecting rod journals for cracks, scratches, grooves or scores.
  2.  
  3. Measure the diameter of each journal at least four places to determine out-of-round, taper or undersize condition.
  4.  
  5. On an engine with a manual transmission, check the fit of the clutch pilot bearing in the bore of the crankshaft. A needle roller bearing and adapter assembly is used as a clutch pilot bearing. It is inserted directly into the engine crank shaft. The bearing and adapter assembly cannot be serviced separately. A new bearing must be installed whenever a bearing is removed.
  6.  
  7. Inspect the pilot bearing, when used, for roughness, evidence of overheating or loss of lubricant. Replace if any of these conditions are found.
  8.  

Main Bearings
  1. Clean the bearing inserts and caps thoroughly in solvent, and dry them with compressed air.
  2.  

Do not scrape varnish or gum deposits from the bearing shells.

  1. Inspect each bearing carefully. Bearings that have a scored, chipped, or worn surface should be replaced.
  2.  
  3. The copper-lead bearing base may be visible through the bearing overlay in small localized areas. This may not mean that the bearing is excessively worn. It is not necessary to replace the bearing if the bearing clearance is within recommended specifications.
  4.  
  5. Check the clearance of bearings that appear to be satisfactory with Plastigage® or its equivalent. Fit the new bearings following the procedure below. They should be reground to size for the next undersize bearing.
  6.  
  7. Regrind the journals to give the proper clearance with the next undersize bearing. If the journal will not clean up to maximum undersize bearing available, replace the crankshaft.
  8.  
  9. Always reproduce the same journal shoulder radius that existed originally. Too small a radius will result in fatigue failure of the crankshaft. Too large a radius will result in bearing failure due to radius ride of the bearing.
  10.  
  11. After regrinding the journals, chamfer the oil holes, then polish the journals with a #320 grit polishing cloth and engine oil. Crocus cloth may also be used as a polishing agent.
  12.  

CHECKING MAINBEARING CLEARANCES



Bearing Clearance

See Figures 1, 2, 3, 4 and 5

Click image to see an enlarged view

Fig. Fig. 1: A dial gauge may be used to check crankshaft end-play



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Fig. Fig. 2: Carefully pry the shaft back and forth while reading the dial gauge for play



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Fig. Fig. 3: A dial gauge may also be used to check crankshaft run-out



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Fig. Fig. 4: Turn the crankshaft slowly by hand while checking the gauge



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Fig. Fig. 5: Mounting a dial gauge to read crankshaft run-out

  1. Check the clearance of each main bearing by using the following procedure:
    1. Place a piece of Plastigage® or its equivalent, on bearing surface across full width of bearing cap and about 1 / 4 " (6mm) off center.
    2.  
    3. Install cap and tighten bolts to specifications. Do not turn crankshaft while Plastigage® is in place.
    4.  
    5. Remove the cap. Using Plastigage® scale, check width of Plastigage® at widest point to get the minimum clearance. Check at narrowest point to get maximum clearance. Difference between readings is taper of journal.
    6.  
    7. If clearance exceeds specified limits, try a 0.001" (0.0254mm) or 0.002" (0.051mm) undersize bearing in combination with the standard bearing. Bearing clearance must be within specified limits. If standard and 0.002" (0.051mm) undersize bearing does not bring clearance within desired limits, refinish crankshaft journal, then install undersize bearings.
    8.  

  2.  

End-Play
  1. Check the crankshaft end-play using the following procedures:
    1. Force the crankshaft toward the rear of the engine.
    2.  
    3. Install a dial indicator so that the contact point rests against the crankshaft flange and the indicator axis is parallel to the crankshaft axis.
    4.  
    5. Zero the dial indicator. Push the crankshaft forward and note the reading on the dial.
    6.  
    7. If the end-play exceeds the wear limit listed in the Crankshaft and Connecting Rod Specifications chart, replace the thrust bearing. If the end-play is less than the minimum limit, inspect the thrust bearing faces for scratches, burrs, nicks, or dirt. If the thrust faces are not damaged or dirty, then they probably were not aligned properly. Lubricate and install the new thrust bearing and align the faces following procedures 21 through 24.
    8.  

  2.  

 
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