VW Passat & Audi A4 1990-2000

Timing Belt

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general information

Timing belts are used to synchronize the crankshaft with the camshaft, similar to a timing chain on an overhead valve (pushrod) engine. Unlike a timing belt, a timing chain could last the life of the engine without needing service or replacement. Timing belts use raised teeth to mesh with sprockets to operate the valve train of an overhead camshaft engine.

Engines, chain or belt-driven, can be classified as either free-running or interference, depending on what would happen if the piston-to-valve timing were disrupted. A free-running engine is designed with enough clearance between the pistons and valves to allow the crankshaft to rotate (pistons still moving) while the camshaft stays in one position (several valves fully open). If this condition occurs normally, no internal engine damage will result. In an interference engine, there is not enough clearance between the pistons and valves to allow the crankshaft to turn without the camshaft being in time.

An interference engine can suffer extensive internal damage if a timing belt fails. The piston design does not allow clearance for the valve to be fully open and the piston to be at the top of its stroke. If the belt fails, the piston will collide with the valve and will bend or break the valve, damage the piston, and/or bend a connecting rod. When this type of failure occurs, the engine will need to be replaced or disassembled for further internal Inspection; either choice costing many times that of replacing the timing belt.

Whenever a vehicle with an unknown service history comes into your repair facility or is recently purchased, here are some points that should be asked to help prevent costly engine damage:



Do you know if, or when, the belt was replaced-
 
If the vehicle is purchased used, or the condition and mileage of the last timing belt replacement are unknown, it is recommended to inspect and replace as necessary
 
Note the mileage of the vehicle. The average replacement interval for a timing belt is approximately 60,000 miles (96,000 km) or every 6 years.
 


WARNING
Timing belt maintenance is extremely important! The A4 and Passat model utilize an interference-type, non-free-wheeling engine. If the timing belt breaks, the valves in the cylinder head may strike the pistons, causing potentially serious (also time-consuming and expensive) engine damage. The recommended replacement interval for the timing belt is at least every 6 years or 60,000-90,000 miles (96,000-144,000 km), depending on vehicle usage and engine type.


NOTE
If the vehicle has been stored for long periods (2 years or more), the belt should be changed before returning the vehicle to service.


WARNING
NEVER allow antifreeze, oil or solvents to come into with a timing belt. If this occurs immediately wash the solution from the timing belt. Also, never excessive bend or twist the timing belt; this can damage the belt so that its lifetime is severely shortened.


NOTE
If removed and reinstalled, the timing belt must be installed in the same rotational direction as removed.

REMOVAL & INSTALLATION

WARNING
Do NOT turn the engine or camshaft with the timing belt removed. The pistons will contact the valves and cause internal engine damage.

2.0L (9A, ABA) Engines
  1. Disconnect the negative battery cable and remove the accessory drive belts, crankshaft pulley and the timing belt cover(s).
  2.  
  3. Temporarily reinstall the crankshaft pulley bolt and turn the crankshaft to TDC of No. 1 piston. The mark on the camshaft sprocket should be aligned with the mark on the inner timing belt cover or the edge of the cylinder head.
  4.  
  5. With the distributor cap removed, the rotor should be pointing toward the No. 1 mark on the rim of the distributor housing. On 8 valve engines, the notch on the crankshaft pulley should align with the dot on the intermediate shaft sprocket.
  6.  
  7. Loosen the locknut on the tensioner pulley and turn the tensioner counterclockwise to relieve the tension on the timing belt.
  8.  
  9. Slide the timing belt from the sprockets.
  10.  



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Fig. Adjusting the belt tension on a 2.0L 8 valve



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Fig. Remove the timing belt cover



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Fig. Align the timing marks



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Fig. Locate the tensioner



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Fig. Loosen the tensioner bolt



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Fig. Mark the belts direction of rotation

To install:

  1. Check the alignment of the timing marks. On 16-valve engines, the mark on the tooth should align with the mark on the rear belt cover.
  2.  
  3. Install the new timing belt and tension the belt so it can be twisted 90° at the middle of it's longest section, between the camshaft and intermediate sprockets.
  4.  
  5. Recheck the alignment of the timing marks and, if correct, turn the engine 2 full revolutions to return to TDC of No. 1 piston. Recheck belt tension and timing marks. Readjust as required. Torque the tensioner nut to 33 ft. lbs. (45 Nm).
  6.  
  7. Install the belt cover and accessory drive belts.
  8.  
  9. If the belt is too tight, there will be a growling noise that rises and falls with engine speed.
  10.  

1.8L (AEB) Engine
  1. Note the radio security code and disconnect the negative battery cable.
  2.  
  3. Place the (hood) lock carrier in the service position. For additional information, please refer to the following topic(s): Body And Trim, Service Position, Front Bumper, Hood Lock Carrier.
  4.  
  5. Remove the engine accessory drive belts. For additional information, please refer to the following topic(s): General Information And Maintenance, Routing Maintenance And Tune-up.
  6.  
  7. Using a 5 x 60mm bolt, secure the viscous fan pulley. Using a hex wrench, remove the viscous fan-to-pulley bolts. Remove the viscous fan assembly.
  8.  
  9. Turn the engine by hand to Top Dead Center (TDC) on the firing stroke for cylinder No. 1.
  10.  
  11. Remove the upper timing belt cover.
  12.  


NOTE
If reusing the timing belt, mark its rotational direction so it may be installed in its original position.

  1. Using the center bolt, rotate the crankshaft in the direction of engine rotation to position the No. 1 cylinder at Top Dead Center (TDC) of its compression stroke.
  2.  
  3. Remove the damper pulley-to-crankshaft bolts and the damper.
  4.  
  5. Remove the lower timing belt cover.
  6.  
  7. Using a Torx® Wrench T45, or equivalent, loosen the timing belt tensioner, push the tensioner downward and remove the timing belt.
  8.  



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Fig. Crankshaft pulley and camshaft sprocket alignment locations-1.8L engine



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Fig. Timing belt tension adjustment-1.8L engine



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Fig. Timing belt tension wear limits-1.8L engine



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Fig. The Top Dead Center (TDC) alignment marks for the camshaft sprocket



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Fig. The timing belt, tensioner and guide roller

To install:

  1. Align the camshaft sprocket timing mark with the cylinder head cover mark.
  2.  
  3. Install the timing belt on the crankshaft sprocket with the arrow facing the rotational direction.
  4.  
  5. Install the lower timing belt cover.
  6.  
  7. Using a bolt, secure the damper/belt pulley on the crankshaft.
  8.  
  9. Align the crankshaft damper/belt pulley with the housing timing mark so that the No. 1 cylinder is at TDC of its compression stroke.
  10.  
  11. Install the timing belt on the camshaft sprocket and belt tensioner.
  12.  
  13. Using a 2-pin Spanner Matra Tool No. V159 Wrench, or equivalent, lift (turn clockwise) the timing belt tensioner cylinder No. 1 until it is fully extended and tensioner cylinder No. 2 is raised approx. 1mm ( 3 / 8 inch); then, hand-tighten the mounting bolt.
  14.  
  15. Rotate the crankshaft 2 complete rotation in the running direction.
  16.  
  17. Inspect area "A" for proper alignment with the upper edge of piston No. 2 and adjust if necessary.
  18.  
  19. Area "A" - adjustment OK
  20.  
  21. Area "B" - wear limit
  22.  
  23. Area "C" - re-adjust and check belt drive including tensioner for wear.
  24.  


NOTE
If the piston edge is located in area "A", measurement "D" is 25-29mm ( 31 / 32 -1 1 / 8 inches).

  1. After adjustment has been verified, secure the tensioner with a 2-pin Spanner Matra Tool No. V159 Wrench, or equivalent, and tighten the mounting bolt.
  2.  
  3. Complete the damper to crankshaft installation.
  4.  
  5. Using the center bolt, rotate the crankshaft 2 rotations in the direction of engine rotation until the camshaft and crankshaft marks align with their respective reference points.
  6.  
  7. Install the upper timing belt cover.
  8.  
  9. Install the drive belts.
  10.  
  11. The balance of assembly is in reverse order of removal.
  12.  
  13. Install the negative battery cable last.
  14.  
  15. Test drive the vehicle.
  16.  

2.8L SOHC (AFC) V6 Engine
  1. Note the radio security code and disconnect the negative battery cable.
  2.  
  3. Place the (hood) lock carrier in the service position. For additional information, please refer to the following topic(s): Body And Trim, Service Position, Front Bumper, Hood Lock Carrier.
  4.  
  5. Remove the engine accessory drive belt. For additional information, please refer to the following topic(s): General Information And Maintenance, Routing Maintenance And Tune-up.
  6.  
  7. Turn the engine by hand to Top Dead Center (TDC) on the firing stroke for cylinder No. 1.
  8.  


NOTE
The large holes in the camshaft sprocket lock plates should be on the inside facing one another.

  1. Remove the Crankshaft Position (CKP) sensor from the lower left side of the engine block. Make sure the engine is at TDC and install the threaded crankshaft holding pin Tool No. 3242 and lightly tighten.
  2.  
  3. Remove the upper timing belt covers, the crankshaft vibration damper and then the lower timing belt cover.
  4.  
  5. Loosen the camshaft sprocket bolts slightly and use a suitable pulley to release the sprockets from the tapered ends of the camshafts.
  6.  
  7. Loosen the tensioner roller and remove the drive belt.
  8.  

To install :

  1. Install the timing belt over the sprockets, then the idler rollers and lastly over the tensioner.
  2.  
  3. Install camshaft alignment tool holder Tool No. 3243 into the camshaft alignment flanges.
  4.  
  5. Check and adjust the cam belt tension such that the upper left portion of the belt between the tensioner and the left cam gear can just be twisted 90° ( 1 / 4 turn).
  6.  
  7. Tighten the cam belt tensioning roller to 33 ft. lbs. (45 Nm), and the camshaft sprocket bolts.
  8.  
  9. The balance of the installation is in reverse order of removal.
  10.  

2.8L DOHC 5V (AHA) V6 Engine
  1. Note the radio security code and disconnect the negative battery cable.
  2.  
  3. Place the (hood) lock carrier in the service position. For additional information, please refer to the following topic(s): Body And Trim, Service Position, Front Bumper, Hood Lock Carrier.
  4.  
  5. Remove the engine accessory drive belt. For additional information, please refer to the following topic(s): General Information And Maintenance, Routing Maintenance And Tune-up.
  6.  
  7. Turn the engine by hand to Top Dead Center (TDC) on the firing stroke for cylinder No. 1.
  8.  


NOTE
The large holes in the camshaft sprocket lock plates should be on the inside facing one another.

  1. On the cylinder block near the crankshaft, remove the sealing plug from the lower left side of the engine block. Make sure the engine is at TDC and install the threaded crankshaft holding pin Tool No. 3242 and lightly tighten.
  2.  
  3. Remove the upper timing belt covers, the crankshaft vibration damper and then the lower timing belt cover.
  4.  
  5. Loosen the camshaft sprocket bolts slightly and use a suitable pulley to release the sprockets from the tapered ends of the camshafts.
  6.  
  7. Using a 8mm Allen® wrench, rotate the timing belt tensioner roller clockwise until the tensioner is compressed; then, insert a 2mm spring pin through the tensioner housing and tensioner plunger to secure it in place. When the plunger is secure, release the wrench tension.
  8.  
  9. Remove the damper-to-crankshaft bolts and the damper.
  10.  


NOTE
It is not necessary to remove the center bolt when removing the crankshaft damper.

  1. Remove the serpentine belt idler and the crankshaft damper guard.
  2.  
  3. Mark the running direction of the timing belt and remove it from the pulleys.
  4.  



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Fig. Crankshaft pulley alignment location for TDC-Audi 2.8L V6 engines



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Fig. Left camshaft sprocket alignment position for TDC; right camshaft position is similar-Audi 2.8L V6 engines



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Fig. View of crankshaft holding tool installed-Audi 2.8L V6 engines



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Fig. View of camshaft locator bar installed-Audi 2.8L V6 engines

To install:

  1. Make sure that the camshaft pulleys and the crankshaft pulley are in alignment with TDC of the No. 1 cylinder's compression stroke.
  2.  
  3. Install the timing belt; make sure the timing belt is installed in the correct running direction from which it was removed.
  4.  
  5. Using a 8mm Allen® wrench, rotate the timing belt tensioner roller clockwise until the tensioner is compressed; then, remove the 2mm spring pin from the tensioner housing. Slowly, release the tensioner spring pressure to put pressure on the timing belt.
  6.  
  7. Install the crankshaft damper guard and the serpentine belt idler pulley; torque the idler pulley bolts to 33 ft. lbs. (45 Nm).
  8.  
  9. Install the crankshaft damper and torque the damper-to-crankshaft bolts to 15 ft. lbs. If the damper-to-crankshaft center bolt was removed, torque it to 147 ft. lbs. (200 Nm) plus 180° 1 / 2 turn).
  10.  
  11. Remove the Crankshaft Holder tool No. 3242 and install the sealing plug.
  12.  
  13. Replace the remaining components by reversing the removal procedures.
  14.  
  15. Refill the cooling system and the automatic transaxle. Connect the electrical connectors. Install the negative battery cable last.
  16.  
  17. Test drive the vehicle.
  18.  

Inspection

Inspect both sides of the timing belt. Replace the belt with a new one if any of the following conditions exist:



Hardening of the rubber-back side is glossy without resilience and leaves no indentation when pressed with a fingernail
 
Cracks on the rubber backing
 
Cracks or peeling of the canvas backing
 
Cracks on rib root
 
Cracks on belt sides
 
Missing teeth or chunks of teeth
 
Abnormal wear of belt sides-the sides are normal if they are sharp, as if cut by a knife.
 

If none of these conditions exist, the belt does not need replacement unless it is at the recommended interval. The belt MUST be replaced at the recommended interval.


WARNING
On interference engines, it is very important to replace the timing belt at the recommended intervals, otherwise expensive engine damage will likely result if the belt fails.


NOTE
For additional information, please refer to the following topic(s): General Information And Maintenance, Routine Maintenance And Tune-Up.



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Fig. NEVER bend or twist a timing belt excessively, and Do NOT allow solvents, antifreeze, gasoline, acid or oil to come into contact with the belt



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Fig. Broken tooth may be due to a damaged pulley



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Fig. Back surface worn or cracked from a possible overheated engine or interference with the belt cover



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Fig. Side wear from improper installation



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Fig. Worn teeth from excessive belt tension, camshaft or distributor not turning properly, or fluid leaking on the belt

 
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