Volkswagen Front Wheel Drive 1974-1989 Repair Guide

Crankshaft and Main Bearings

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REMOVAL & INSTALLATION



See Figure 1



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Fig. Fig. 1: Cylinder block and crankshaft

  1. Remove the engine from the vehicle and remove the cylinder head.
  2.  
  3. Remove the oil pan, oil pump, flywheel and the front and rear main seals.
  4.  
  5. Remove the piston and rod assemblies.
  6.  
  7. If not already identified, mark the main bearing caps for location and direction. They must face the same direction when installed.
  8.  
  9. Loosen all the bolts and remove the main bearing caps.
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  11. Remove the crankshaft and bearing inserts. Clean and inspect the engine block. If this is a high mileage engine, a machine shop should check the main bearing bore alignment.
  12.  

To install
  1. After all parts are fully prepared for assembly and the bearing oil clearance has been checked, lubricate the upper main bearing inserts with new engine oil and fit them into the engine block.
  2.  
  3. If the engine uses a 6-piece center bearing, install the upper thrust bearing washers.
  4.  
  5. Lubricate the bearing inserts and the crankshaft journals. Slowly and carefully lower the crankshaft into position.
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  7. Lubricate and fit the bearing inserts into the bearing caps and set the caps into place. Don't forget the thrust washers on the center bearing.
  8.  
  9. Start all the bolts and torque them in 3 steps to 48 ft. lbs. (65 Nm). Turn the crankshaft between each step to make sure there is no binding.
  10.  

CLEANING AND INSPECTION



See Figures 2, 3 and 4

With the crankshaft removed from the engine, clean the crank, bearings and block areas thoroughly. Visually inspect each crankshaft section for any sign of wear or damage, paying close attention to the main bearing journals. Any scoring or ridges on the crankshaft means the crankshaft should be repaired or replaced. Using a micrometer, measure the diameter of each journal on the crankshaft and record the measurements. The acceptable specifications for both connecting rod and main journals are found in the Crankshaft and Connecting Rod specifications chart in this section. If any journal is beyond the acceptable range, the crank must be repaired or replaced. Repair is possible by having the crankshaft machined to a standard undersize. In most cases, however, some thought should be given to replacing the damaged crankshaft with a reground shaft kit. A reground crankshaft kit contains the necessary main and rod bearings for installation. The shaft has been ground and polished to undersize specifications and will usually hold up well if installed correctly. Most automotive machine shops are able to provide this service.

Check the bearing oil clearance. The procedure described here assumes the engine is out of the vehicle. The oil clearance can be checked with the engine installed to help determine main bearing and crankshaft condition. Follow the same procedure but remove only one main bearing cap at a time.

  1. With the upper bearing inserts and the crankshaft installed, wipe the oil from the main journal on the crankshaft so it is dry.
  2.  
  3. Lay a piece of Plastigage® on the crankshaft and install the bearing cap with the bearing. Make sure the bearing is dry and torque the cap bolts to 48 ft. lbs. (65 Nm).
  4.  
  5. Remove the bolts and cap. The Plastigage® may not stick to the crankshaft, so don't drop it when removing the cap.
  6.  



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Fig. Fig. 2: Measure the gauging material to determine the bearing clearance

  1. Use the gauge and conversion table printed on the package to determine the bearing clearance.
  2.  

The crankshaft end-play and connecting rod side clearance should also be checked. Place a prybar between a main bearing cap and crankshaft casting taking care not to damage any journals. Pry backward and forward and measure the distance between the thrust bearing and crankshaft with a feeler gauge. Compare reading with specifications. If too great a clearance is determined, a larger thrust bearing or crank machining may be required. Connecting rod clearance between the rod and crank throw casting can be checked with a feeler gauge. Pry the rod carefully to one side as far as possible and measure the distance on the other side of the rod. If the clearance is excessive, the connecting rods may have to be replaced. Consult an automotive machine shop for their advice.



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Fig. Fig. 3: A dial indicator can be used to check crankshaft end-play



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Fig. Fig. 4: Carefully pry the shaft back and forth while reading the dial for play

BEARING REPLACEMENT



See Figures 5 and 6

The bearing oil clearances should be checked to determine if replacement is required. If the bearing inserts are replaced, recheck the oil clearance to be sure the correct bearings were installed.

Engine Installed

Main bearings may be replaced while the engine is still in the vehicle by rolling them out. Special roll-out pins are available from automotive parts houses or can be fabricated from a cotter pin (see illustration). The roll out pin fits in the oil hole of the main bearing journal. When the crankshaft is rotated opposite the direction of the bearing lock tab, the pin engages the end of the bearing and rolls out the insert.

  1. Remove main bearing cap and roll out the upper bearing insert. Remove the insert from main bearing cap. Clean the inside of the bearing cap and crankshaft journal.
  2.  

To install:

Main bearing inserts with the lubrication grooves must be installed in the block. Inserts without grooves are installed in the bearing caps.

  1. Lubricate and roll upper insert into position, make sure the lock tab is anchored and the insert is not cocked. Install the lower bearing insert into the cap, then lubricate and install it on the engine. Make sure the main bearing cap is installed facing in the correct direction, then torque the bolts in 3 steps to 48 ft. lbs. (65 Nm).
  2.  



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Fig. Fig. 5: Home made bearing roll-out pin



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Fig. Fig. 6: Remove or install the upper bearing insert using a roll-out pin

Engine Removed
  1. Remove the piston and rod assemblies. Remove the main bearing caps after marking them for position and direction.
  2.  
  3. Remove the crankshaft and bearing inserts. Clean the engine block and cap bearing saddles.
  4.  

To install:

The main bearing inserts with lubrication grooves must be installed in the block. Inserts without grooves are installed in the bearing caps.

  1. Install the main bearing upper inserts into the engine block.
  2.  
  3. Lubricate the bearing inserts and the crankshaft journals. Slowly and carefully lower the crankshaft into position.
  4.  
  5. Install the bearing inserts into the bearing caps, then install the caps. Torque cap bolts in 3 steps to 48 ft. lbs. (65 Nm).
  6.  

 
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