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Audi ur-quattro I5 Turbo Engines - Cam Belt Change

Cam belt changes should be carried out every 60,000km (45,000km preferred) or every five years, whichever comes sooner. The official procedure places the car on a lift and performs the operations on the harmonic damper bolt (crankshaft bolt or pulley bolt) from below using two Audi service tools - VAG 2084 to lock the crank, and VAG 2079 as a simple torque-multiplying lever.

There are two issues with the official procedure; there may not be a lift available, and even if there is the car may have had a minor (otherwise indetectable) frontal impact that has reduced the clearance required to get the 2079 to engage the bolt.

Accordingly the procedure detailed here is for the long-winded and time-consuming approach of removing the bumper and valance.

In the following discussion, "remove" means "undo, take off the car and store". "Detach" means "undo and leave on the car".

1. Place front of car on ramps (special low-gradient type required) or axle stands
2. Remove headlight trims, radiator grill
3. Remove headlights
4. If removeable transom fitted, detach end of bonnet release cable (7mm) and remove transom
5. Loosen hydraulic pump pivot bolt, slacken and remove adjuster, detach belt
6. Remove hydraulic pump pivot bolt or - if fouled by auxiliary radiator - bracket mounting bolts
7. Remove upper cambelt cover (6mm Allen), spacers & upper securing stud - if the upper stud comes out with the screw and the spacer falls, there is no way back and the strip-down is commited
8. Remove left and right undertrays
9. Loosen alternator pivot bolt and adjuster, remove alternator and hydraulic pump belts
10. Drain coolant
11. Remove auxiliary radiator (loosen but do not remove two 10mm nuts underneath - auxiliary radiator slides out backwards)
12. Remove plug wires, plug wire shroud & distributor cap
13. Pull off rotor arm, remove dust cap, replace rotor arm (for roughly locating TDC)
14. Detach top coolant hose from radiator
15. Tie hydraulic pump up out of way
16. Disconnect foglight connectors and feed down into bumper mounting space
17. If possible (siphon tube) drain windscreen washer fluid - otherwise have 10mm bolt to hand
18. Remove single 17mm hex head bolt each side through headlight space to release bumper
19. If possible with an assistant, remove bumper from car, disconnect headlight washer hose, and - if reservoir not empty - plug hose with 10mm bolt.
20. Remove valance. This can be extremely difficult and often requires determined long-range drilling. After performing this operation on an old car from a "salt area", few will doubt that stainless fittings sometimes have merit.
21. Turn engine to TDC (cam/distributor) using #3036 on cam wheel, spanner on cam wheel bolt (19mm) or #2079 on harmonic balancer bolt (if car on lift)
22. Lock crankshaft with tool #2084. Do NOT use transmission.
23. Loosen water pump & rotate to loosen cambelt
24. Remove belt from cam sprocket wheel
25. Remove lower cam belt cover
26. Remove harmonic damper bolt and withdraw pulley and belt
27. Remove rear cam cover securing bolt from lower side of cylinder head
28. Remove three upper oil pump securing bolts to free rear cam cover plate
29. Remove water pump retaining bolts and remove water pump from engine
30. Clean block face behind water pump

Notes:

• The Woodruff key forged into the back of the harmonic damper pulley should be inspected after removal. If there is the lightest hint of cracking the pulley should be replaced. This usually involves drilling the heads off the four Allen bolts that secure the pulley to the harmonic damper. Although the harmonic damper (sometimes erroneously called the "pulley" because it drives two or three belts) is hideously expensive, the actual pulley itself (which drives the cam belt) is quite cheap and well worth replacing. Four new bolts WILL be needed.
• Re-assembly is the reverse of disassembly. Check that both the flywheel and the cam gear are at TDC before replacing the belt and crank pulley.
  
• Turn the engine at least once by hand before starting it.
• The idler roller, if fitted, should be changed during any cam belt change after 60,000 miles. It is technically an oil pump part. See the notes on the torque settings page.
• The harmonic damper bolt CANNOT be tightened using an air wrench. Either use Audi's 2079 torque multiplier and a standard torque wrench or a torque wrench rated above 500Nm - in either case the lever will be around five feet long.

Special Tools:

• Audi 2084 crank locking tool. This tool is ESSENTIAL - all other ways of locking the crankshaft carry risks far higher than the cost of a 2084, which can be obtained from any Audi main dealer or by mail order

Parts required:

Note: The face dimensions of all I5 engines are identical. It is possible to upgrade early engines to later specifications by changing all of the necessary parts - if this has been done, it may not be obvious and some or all of the parts here will not fit.

The basic story is:

• The first ur-quattros had a short 113-tooth belt with square profile teeth and no idler roller. Technically, the idler roller is a "reversing roller" and its function is to bring more belt teeth into contact with the cam and crank pulleys. Although it wasn't fitted to the early ur-quattros, the oil pump casting has the recess to mount it and some owners have fitted the longer (120-tooth) belt and its 74mm idler roller.
• From 85-E-900 001 (Model Year 1984) to 85-J-900 643 the 120-tooth belt was fitted with a 74mm idler roller. Tooth profiles were still square and the crank and cam pulley and water pump were unchanged. See below for the aluminium WR engine and the Sport.
• From 85-J-900 644 to the end of the MB (Series 2 MBs - end of 1989 Model Year) a 142-tooth belt was fitted with a smaller (68.7mm) idler roller. This belt had a different tooth profile - rounded instead of square, so the crank and cam gears and the water pump were changed to suit the new profile. It is generally known as the "Supertorque" belt and was also fitted to WR aluminium engines. EXTREME CARE - a limited number of MBs have the older engine even beyond this VIN number.
• The 20V RR and the Sport used a longer (147-tooth) belt with the same rounded profile as the Series 2 MB. The crank and cam gears and the water pump were not changed - the earlier and larger (74mm) idler roller brought more teeth into contact with the cam and crank gears - the belt was extended by a length equivalent to five teeth to accomodate this.

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