When I changed my belts I couldn't find much info on the web about how to do the job. I posed the question so that I could publish the answer to help others. Here is the process:
I bought a belt kit from German & Swedish for about £70. The job took me about 5 hours but would have been about 3.5 hours had I had the info below.
Cam Belt Replacement
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1. Remove the under engine cover.
2. Remove the front grill (bent coat hanger covered in tape) and lift the radiator to the forward position.
3. Remove the pump belt cover, 2x13mm bolts.
4. Rotate the engine (30mm socket on crank bolt) until the timing mark (quite small) on the inside edge of the pump pulley wheel aligns with the notch on the underside of the pump housing.
5. Locate the 'L' shaped plastic on the top of the bell housing and remove it. You will see the flywheel beneath it.
6. Rotate the crank as necessary to line up the crank timing mark (a '0' with a line through it) with the edge in the middle of the aperture in the bell housing.
7. There is a sensor on the top of the bell housing held in with a 10mm bolt. Remove it and the ring gear should be visible.
8. Lock the ring gear with a wide bladed screwdriver wrapped in tape to protect the hole.
9. This will allow the crank pulley bolt to be removed, it is very very tight!
10. Remove the ribbed belt by removing the power steering pump pulley (note for reassembly that the part no. is stamped on the front face).
11. Remove the crank pulley (4x allen screws, do not round them).
12. Remove cam belt covers exposing the belt.
13. At the back of the engine, mark the position of the pump drive pulley (the one on the cam) either pencil line and/or light chisel mark/scratch. It is worth drawing a line on the pump flywheel and the top of the pump housing for reference.
14. Slacken the cam belt tensioner and remove the belt.
15. Remove the old tensioner if fitting a new one (normally supplied as part of the belt kit).
16. Rotate the water pump by hand feeling for any play or roughness. If in doubt change it now before it shreds your new belt.
17. Inspect the old belt for signs of uneven wear or unusual damage.
18. If all is well fit the new belt. Make sure that none of the timing marks have moved. Use some small bore rubber pipe as a wedge to hold the belt in place on the crank pulley.
19. The belt on the left (towards the rear of the van) should be tight between the crank pulley and the cam pulley.
20. Pull it tight around the cam pulley and fit the new tensioner.
21. Lightly tighten the tensioner bolt so that it will allow you to tension it. Tension it so that the right edge of the pointer lines up with the right edge of the pointer back plate.
22. Replace the crank pulley and bolt (not full torque).
23. Remove the 'locking' screw driver and rotate the crank two complete revolutions.
24. Check that the tensioner pointer right edge still roughly lines up with the right edge of the rear pointer plate. If not, re-tension it and rotate the crank another 2 revs. Repeat until the tensioner no longer needs readjustment (some tolerance is allowable). Torque the tensioner bolt to 20Nm.
25. Reinsert the 'locking' screwdriver when the alignment marks are aligned.
26. Remove the crank pulley and replace the cam belt covers.
27. Refit the crank pulley and re-torque the bolt (460Nm) or just very tight.
28. Refit the ribbed belt making sure the power steering pulley is the correct way around (see note earlier).
Pump Belt Replacement
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1. Make sure all the marks align accurately including the one on the pump flywheel.
2. Note the alignment of the existing tensioners (there are 2) particularly the position of the pointer on the rear one.
3. Remove the tensioners and the belt.
4. Check the old belt for unusual wear.
5. Fit the new rear tensioner so that its pointer is in the same position of the one removed (should align with the edge of the housing).
6. Fit the new belt so that it is tight around the both pulleys. This may require the tensioner to be slackened slightly to allow the belt to be fitted. Some clothes pegs can be used to help hold the belt on the pulleys.
7. Fit the front tensioner so that everything is in place. Set the rear tensioner in the correct position.
8. Tighten the front tensioner and tension it so that the pointer lines up with the 'V'.
9. Remove the locking screwdriver and pegs and rotate the crank 2 complete revs.
10. Check the tensioner arrows and re-tension if necessary. Repeat until the arrow remains over the 'V' back plate. Torque tensioners to 20Nm.
At this point I would carefully check your work and make sure that all the marks line up. Check that the engine is in a state where it can be started. Start it and make sure that it runs as it should. If you are not happy, turn it off and investigate.
Pump Timing
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1. If your timing was OK before and your new tensioners are fitted in roughly the same place as the old one then you should be OK.
2. The only way to check the timing dynamically is to use a VAGCOM interface (or similar) connected to the engine's CAN bus.
3. You need to read Channel 0 Engine Basic Settings. Field 2 is advance and 9 is fuel temperature.
4. Google for 'audi vw diesel timing pdf' information to find the ACV engine timing graph.
5. You can draw your own graph (ACV engine up to 4/99), the x axis runs from 20 to 180, the y axis from 0 to 80. Draw a line from position 20,55 to 180,35. Draw a line from 20,75 to 180,55. Shade in the area between the 2 lines. This is the allowable timing region.
6. The graph for the ACV engine from 4/99 onwards is independent of fuel temp. ie. you just need to measure the advance from field 2. The allowable limits are 38 - 68.
7. Run the engine and make sure that you are in BASIC SETTINGS, the glow plug light should flash on the dash. Read the advance and fuel temp values. Check that they are in the shaded section of the appropriate graph.
8. If the timing is out, work out whether you need to advance or retard the pump.
9. Line up the timing marks and in particular your pump flywheel mark.
10. Using a pulley holding tool (eBay) or 2 lengths of steel strip & a couple of bolts (B&Q) hold the pump belt drive pulley still (the one on the cam, NOT the pump) and slacken the centre bolt.
11. Rotate the pump flywheel in the appropriate direction by a VERY small amount (1mm at the circumference of the flywheel) and re-tighten the drive pulley centre bolt. You may need an assistant.
12. Run the engine and measure the timing with the VAGCOM again. Based on your previous adjustment work out how much more adjustment to make. If you are already in the shaded section I would quite while you're ahead!
I offer the above information in good faith. It is the procedure that I followed when I did my own van and it all worked well. If you are not confident, do not have the correct tools or haven't done anything similar before I would stop now.
Good Luck or rather Good Skill!
Kevin
March 2008
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