VW passat B6. Looking from car forward i have found lot of soot on the camshaft drive belt cover. This is over the alternator close to device with rubber thin hoses and plastick lever going towards engine block

hi you have to remove the timing belt and redo your timing there is a spesial tool to lock camshaft pullrys and crank shaft pulley.

The serpentine belt diagram for 1998 VW Passat 1.9 TDI:



CS = Crankshaft
F = Fan pulley
Gen = Alternator
T = Tensioner
AC = Air Conditioning
PAS = Power Assisted Steering

Hi, I have pasted instructions below from autozone.com. The instructions call for the use of special tools. You can improvise with alternate tools, but please make sure your timing is right before closing the cover. Please let me know if you have questions, and thanks for using FixYa.

1.9L Diesel Engine
Some special tools are required to perform this procedure properly. A flat bar, VW tool 2065A is used to secure the camshaft in position. A pin, VW tool 2064 is used to fix the pump position while the timing belt is removed. The camshaft and pump work against spring pressure and will move out of position when the timing belt is removed. It is not difficult to find substitutes but do not remove the timing belt without these tools.

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

1. Disconnect the negative battery cable and remove the accessory drive belts, crankshaft pulley and the timing belt cover(s). Remove the camshaft cover and rubber plug at the back end of the camshaft.
2. Temporarily reinstall the crankshaft pulley bolt and turn the crankshaft to Top Dead Center (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.
3. With the engine at TDC, insert the bar into the slot at the back of the camshaft. The bar rests on the cylinder head to will hold the camshaft in position.
4. Insert the pin into the injection pump drive sprocket to hold the pump in position.
5. Loosen the locknut on the tensioner pulley and turn the tensioner counterclockwise to relieve the tension on the timing belt. Slide the timing belt from the sprockets.
   
   
   

   Fig. Use the VW tool to lock the camshaft at TDC for timing belt replacement-Volkswagen 1.9L Diesel engines
   
   
   
   

   Fig. Locking the injection pump with the VW tool as shown-Volkswagen 1.9L Diesel engines
   

To install:

1. Install the new timing belt and adjust the tension so the belt can be twisted 45 degrees at the halfway point between the camshaft and pump sprockets. Tighten the tensioner nut to 33 ft. lbs. (45 Nm).
2. Remove the holding tools.
3. Turn the engine 2 full revolutions to return to TDC for the No. 1 cylinder. Recheck belt tension and timing mark alignment, readjust as required.
4. Install the belt cover and accessory drive belts.
   NOTE If the belt is too tight, there will be a growling noise that rises and falls with engine speed.

It's a lot of work. You need to remove the bumper cover and steel bumper and pull the radiator support forward so you have some room to work. After getting the belt off you unbolt the A/C compressor and let it hang, don't disconnect hoses. Then you have enough access to get the alternator out. It has to come out from the bottom. Make sure you disconnect the battery before starting.

The serpentine belt routing diagram for 2003 VW Passat V5 2.3 liter


CS = Crankshaft
F = Fan pulley
Gen = Alternator
G = Guide pulley
T = Tensioner pulley
AC = Air Conditioning
PAS = Power Assisted Steering

Belt routing diagram for 1997 VW Passat 1,9 TDI:


CS = Crankshaft
F = Fan pulley
Gen = Alternator
T = Tensioner
AC = Air Conditioning
PAS = Power Assisted Steering
WP = Water Pump

volkswagen passat I have attached link for your proper reference. Ask their live chat for assistance.
All the best

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

VW Passat & Audi A4 1990-2000 Repair Guide
Timing Belt - 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. 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.
3. 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.
4. Loosen the locknut on the tensioner pulley and turn the tensioner counterclockwise to relieve the tension on the timing belt.
5. Slide the timing belt from the sprockets

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



Fig. Remove the timing belt cover




Fig. Align the timing marks





Fig. Locate the tensioner




Fig. Loosen the tensioner bolt




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. 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.
3. 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).
4. Install the belt cover and accessory drive belts.
5. If the belt is too tight, there will be a growling noise that rises and falls with engine speed.

continue...

when you are looking at the engine pull off the plastic cover on top then the front cover that covers you timing belt there is a wire harness tha goes right to it in the left upper coner two ten mil bolts and it comes off careful not to drop bolts down in belt that could be bad. it is that easy

Its on the front of the cylinder head, behind camshaft timing belt cover and sensor housing. Good luck