Chrysler Full-Size Trucks 1967-1988 Repair Guide

Rear Main Seal

Print

REMOVAL & INSTALLATION



One-Piece Seal

See Figure 1

  1. Remove the transmission, clutch assembly or converter and flywheel.
  2.  
  3. Lower the oil pan if necessary for working room.
  4.  
  5. On gasoline engines, use an awl to punch two small holes on opposite sides of the seal just above the split between the main bearing cap and engine block. Install a sheet metal screw in each hole. Use two small prybars and pry evenly on both screws using two small blocks of wood as a fulcrum point for the prybars. Use caution throughout to avoid scratching or damaging the oil seal mounting surfaces.
  6.  
  7. On diesel engines, remove the bolts that secure the oil seal retaining plate. Grasp and pull the oil seal assembly from the crankshaft.
  8.  
  9. When the seal has been removed, clean the mounting recess.
  10.  
  11. Coat the seal and block mounting surfaces with oil. Apply white lube to the contact surface of the seal and crankshaft. Start the seal into the mounting recess and install with a seal driver. After inserting the seal on diesel engines, install the oil seal retaining plate, then tighten the bolts to 2.2 ft. lbs. (3 Nm).
  12.  



Click image to see an enlarged view

Fig. Fig. 1: Inserting the side seal on a diesel

  1. Install the remaining components in the reverse of removal.
  2.  

Two-Piece Seal

See Figures 2 through 7

  1. Remove the oil pan and the oil pump (if required).
  2.  
  3. Loosen all the main bearing cap bolts, thereby lowering the crankshaft slightly but not to exceed 1 / 32 in. (0.8mm).
  4.  
  5. Remove the rear main bearing cap, then remove the oil seal from the bearing cap and cylinder block. On the block half of the seal use a seal removal tool, or install a small metal screw in one end of the seal, and pull on the screw to remove the seal. Exercise caution to prevent scratching or damaging the crankshaft seal surfaces.
  6.  



Click image to see an enlarged view

Fig. Fig. 2: Rear main bearing cap on V8-318



Click image to see an enlarged view

Fig. Fig. 3: Rear main seal 6-198 and 225



Click image to see an enlarged view

Fig. Fig. 4: Removing the lower seal half

  1. Remove the oil seal retaining pin from the bearing cap if so equipped. The pin is not used with the split-lip seal.
  2.  
  3. Carefully clean the seal groove in the cap and block with a brush and solvent such as lacquer thinner, trichloroethylene, or equivalent. Clean the area thoroughly, so that no solvent touches the seal.
  4.  

To install:
  1. Dip the split lip-type seal halves in clean engine oil.
  2.  
  3. Carefully install the upper seal (cylinder block) into its groove with undercut side of the seal toward the FRONT of the engine, by rotating it on the seal journal of the crankshaft until approximately 3 / 8 in. (9.5mm) protrudes below the parting surface.
  4.  

Be sure no rubber has been shaved from the outside diameter of the seal by the bottom edge of the groove. Do not allow oil to get on the sealer area.

  1. Tighten the remaining bearing cap bolts to the specifications listed in the Torque chart in this information.
  2.  



Click image to see an enlarged view

Fig. Fig. 5: Removing and installing the upper main bearing

  1. Install the lower seal in the rear main bearing cap, with the undercut side of seal toward the FRONT of the engine, allow the seal to protrude approximately 3 / 8 in. (9.5mm) above the parting surface to mate with the upper seal when the cap is installed.
  2.  
  3. Apply an even 1 / 16 in. (1.6mm) bead of RTV silicone rubber sealer to the rope seal section. Do not apply any to the side area. Refer to the diagram given earlier in this information.
  4.  

This sealer sets up in about 15 minutes.

  1. Install the rear main bearing cap. Tighten the cap bolts to specifications.
  2.  



Click image to see an enlarged view

Fig. Fig. 6: Oil pan seal at the rear bearing on the 6-238 and 8-318, 360 engines



Click image to see an enlarged view

Fig. Fig. 7: Modified rear main bearing rope seal

  1. Install the oil pump and oil pan. Fill the crankcase with the proper amount and type of oil.
  2.  
  3. Operate the engine and check for oil leaks.
  4.  

Crankshaft and Main Bearings 6-198 and 6-225 Engines

The maximum allowable bearing clearance is 0.001 in. (0.02mm)

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 bearing. Finally, 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 in. (0.21mm). Replace No. 3 (thrust) bearing if end-play exceeds that amount. Undersized bearings are available in the following sizes: 0.001 in. (0.21mm), 0.002 in. (0.05mm), 0.003 in. (0.07mm), 0.010 in. (0.25mm), 0.012 in. (0.30mm). Never install an undersize bearing that will reduce the clearance to below specification.

6-251 Engine

Crankshaft end-play is checked with a dial indicator between the end of the rear main bearing and the thrust shoulder. Maximum bearing taper and out-of-round is 0.001 in. (0.21mm) Undersized bearings are available in the following sizes: 0.001 in. (0.21mm), 0.002 in. (0.05mm), 0.003 in. (0.07mm), 0.010 in. (0.25mm), 0.020 in. (0.50mm), 0.030 in. (0.76mm), 0.040 in. (1.0mm) .

V6 and V8 Gasoline Engines

See Figure 8

A Maltese Cross stamped on the engine (except on the 238, 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 journals finished 0.001 in. (0.025mm) undersize. The position of the underside journal(s) is stamped on a machine surface of the No. 3 counterweight. On the 238, marks are stamped near the notch of the No. 6 crankshaft 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 in. (0.25mm) undersize. On the 318 and 360 engines, 0.001 in. (0.02mm) 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 in. (0.25mm) undersize.

Upper and lower bearing inserts are not interchangeable on any of the V8 engines due to the oil hole and V-groove in the uppers. On the 238 cu.in. engine, the lower main bearing halves of No 1, and 3 are interchangeable, while the upper and lower No. 2 are flanged and not interchangeable. On the 318 and 360 cu.in. engine, the lower and upper bearing halves of No. 1, No. 2 and No. 4 are interchangeable, while the 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, while 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 of the piece. No. 3 bearing is a thrust bearing and should be replaced if end-play exceeds 0.007 in. (0.17mm).



Click image to see an enlarged view

Fig. Fig. 8: The main bearings found in these engines are of the replaceable inserts type which are installed in the block and bearing cap

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

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



Gasoline Engines

See Figures 9, 10 and 11

  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 the earlier procedure on removing the front cover, in this information.
  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.  



Click image to see an enlarged view

Fig. Fig. 9: Carefully loosen and remove the main bearing cap retainers

  1. Remove the main bearings caps.
  2.  
  3. 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.
  4.  
  5. Remove the rear journal seal from the block and rear main bearing cap.
  6.  
  7. Remove the main bearing inserts from the block and bearing caps.
  8.  
  9. Remove the connecting rod bearing inserts from the connecting rods and caps.
  10.  
  11. 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.
  12.  
  13. 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.
  14.  
  15. Install the lower main bearing inserts in the bearing caps.
  16.  



Click image to see an enlarged view

Fig. Fig. 10: Installing the main bearing inserts



Click image to see an enlarged view

Fig. Fig. 11: ALWAYS use a torque wrench to assure proper tightening of the main bearing cap retainers

  1. Clean the rear journal oil seal groove and the mating surfaces of the block and rear main bearing cap.
  2.  
  3. 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.
  4.  

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.  

Diesel Engines
  1. With the engine secured on a workstand, with the cylinder head unfastened and placed aside, start by removing the top ridge from cylinder sleeve with a Ridge Reamer, tool C-3012.
  2.  

Keep tops of pistons covered during this procedure.

  1. As each piston and rod assembly is pushed out of bore, match the cap and rod assemblies. Also, identify the pistons and rods by cylinder.
  2.  
  3. Rotate the crankshaft to center each one of the connecting rods in the bore. Remove cap.
  4.  
  5. Turn the block sideways to remove the pistons and rod assemblies through the top of the block. Use bolt covers to protect journal surfaces. Push on upper bearing inserts with a hardwood blocks to remove assemblies.
  6.  
  7. Remove the main bearing caps from Nos. 1 and 7 bearings using puller C-3752-D and adapters. Remove the lower bearing inserts. Make sure to mark them as to cap number.
  8.  
  9. Remove the caps from Nos. 2 through 6 main bearings using the puller and adapters. Remove the lower bearing inserts. Make sure to mark them as to cap number.
  10.  
  11. Lift out the crankshaft.
  12.  
  13. Remove the upper bearing inserts. Identify the upper main bearings inserts, mate with corresponding lower main bearing inserts. Identify bearing pairs as to cap number.
  14.  
  15. Remove the thrust plates from No. 7 main bearing journal.
  16.  

CLEANING AND INSPECTION



Crankshaft

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 in at least four places to determine the 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 crankshaft. The bearing and adapter assembly cannot be serviced separately.
  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 Crankshaft and Main Bearings removal and installation, 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.  

INSPECTION AND REPLACEMENT



Gasoline Engines

See Figures 12, 13 and 14

  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 in. (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 in. (0.0254mm) or 0.002 in. (0.051mm) undersize bearing in combination with the standard bearing. Bearing clearance must be within specified limits. If standard and 0.002 in. (0.051mm) undersize bearing does not bring clearance within desired limits, refinish crankshaft journal, then install undersize bearings.
    8.  

  2.  



Click image to see an enlarged view

Fig. Fig. 12: Use Plastigage® to check the clearance on the bearing surface and caps

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. 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 the procedure outlined earlier.
    8.  

  12.  



Click image to see an enlarged view

Fig. Fig. 13: A feeler gauge may be used to check end-play in a crankshaft



Click image to see an enlarged view

Fig. Fig. 14: If a dial gauge is available, it may also be used to check crankshaft end-play

  1. 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.
  2.  
  3. Install new bearing inserts in the connecting rods and caps. Check the clearance of each bearing, following the procedure (1a through 1d).
  4.  
  5. After the connecting rod bearings have been fitted, apply a light coat of engine oil to the journals and bearings.
  6.  
  7. 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.
  8.  
  9. Install the connecting rod cap. Tighten the nuts to specification.
  10.  
  11. After the piston and connecting rod assemblies have been installed, check the side clearance with a feeler gauge between the connecting rods on each crankshaft journal. Refer to Crankshaft and Connecting Rod specifications chart in this information.
  12.  
  13. Install the timing chain, sprockets or gears, cylinder front cover and crankshaft pulley and adapter. Following the steps under Front Cover and Timing Chain Installation in this information.
  14.  

Diesel Engines

See Figures 15, 16 and 17

  1. Support the crankshaft on V-blocks under Nos. 1 and 7 journals.
  2.  
  3. Mount a dial indicator contacting the center main bearing journal.
  4.  
  5. Rotate the crankshaft and note the reading. This is the crankshaft runout. One half of the runout is known as "bend''. Bend should be 0.0011 in. (0.03mm) or less. If bend exceeds 0.0027 in. (0.07mm), replace the crankshaft.
  6.  



Click image to see an enlarged view

Fig. Fig. 15: A dial gauge must be used to check crankshaft runout



Click image to see an enlarged view

Fig. Fig. 16: Mounting a dial gauge to read crankshaft runout

  1. Inspect all journals for wear, damage or overheating (blue color).
  2.  
  3. 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 in. (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 in. (0.0254mm) or 0.002 in. (0.051mm) undersize bearing in combination with the standard bearing. Bearing clearance must be within specified limits. If standard and 0.002 in. (0.051mm) undersize bearing does not bring clearance within desired limits, refinish crankshaft journal, then install undersize bearings.
    8.  

  4.  

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.  



Click image to see an enlarged view

Fig. Fig. 17: Crankshaft thrust bearing alignment

  1. Retain the forward pressure on the crankshaft. Tighten the cap bolts to specifications.
  2.  
  3. 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 above.
    8.  

  4.  
  5. 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.
  6.  
  7. Install new bearing inserts in the connecting rods and caps. Check the clearance of each bearing, following the procedure.
  8.  
  9. After the connecting rod bearings have been fitted, apply a light coat of engine oil to the journals and bearings.
  10.  
  11. 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.
  12.  
  13. Install the connecting rod cap. Tighten the nuts to specification.
  14.  
  15. 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 information.
  16.  
  17. Install the timing chain and sprockets or gears, cylinder front cover and crankshaft pulley and adapter, following steps under Front Cover and Timing Chain Installation in this information.
  18.  

COMPLETING THE REBUILDING PROCESS



Fill the oil pump with oil, to prevent cavitating (sucking air) on initial engine start up. Install the oil pump and the pickup tube on the engine. Coat the oil pan gasket as necessary, and install the gasket and the oil pan. Mount the flywheel and the crankshaft vibration damper or pulley on the crankshaft.

Always use new bolts when installing the flywheel. Inspect the clutch shaft pilot bushing in the crankshaft. If the bushing is excessively worn, remove it with an expanding puller and a slide hammer, and tap a new bushing into place.

Position the engine, cylinder head side up. Lubricate the lifters, and install them into their bores. Install the cylinder head, and torque it as specified. Insert the pushrods (where applicable), and install the rocker shaft(s), if so equipped or position the rockers.

Install the intake and exhaust manifolds, the carburetor(s), the distributor and spark plugs. Mount all accessories and install the engine in the truck. Fill the radiator with coolant, and the crankcase with high quality engine oil.

BREAK-IN PROCEDURE



Start the engine, and allow it to run at low speed for a few minutes, while checking for leaks. Stop the engine, check the oil level, and fill as necessary. Restart the engine, and fill the cooling system to capacity. Check and adjust the ignition timing. Run the engine at low to medium speed (800-2,500 rpm) for approximately 1 / 2 hour, and retorque the cylinder head bolts. Road test the truck, and check again for leaks.

Some gasket manufacturers recommend not retorquing the cylinder head(s) due to the composition of the head gasket. Follow the directions in the gasket set.

 
label.common.footer.alt.autozoneLogo