peterlavoie

Well I decided to take the plunge with the timing belt change on a 3.0 L AVK engine in a 2002 Audi A4. Equipped with the Bentley book for the car, readings of procedures on this and similar sites, the instructions provided by the online parts supplier and several viewings of various YouTube videos I felt I was ready. What continuously bothered me is that in all of the documentation and videos I had never seen described how to insert the crankshaft locking pin. All the resources went to great effort to describe that the installation of this pin was absolutely necessary but shed no light on how to do it. In fact very obscure descriptions exist on where to find its insertion point. So I undertook the job with the cam lock gauges installed and no crank locking pin installed. Since the cam gauges seemed robust enough to withstand the cam pulley torque of 75 ft lbs it seemed unnecessary to have any torque resistance at the crankshaft. In any case since the timing belt is in place during the cam torqueing any movement would be seen at both the cams and the crank such that their relative positions would remain unchanged. Despite this, my engine ended up about 8 degrees retarded after the installation and misfired on all cylinders at less than 2,000 RPM.

It is fairly obvious why writers do not deal in any detail with the crank locking pin installation, the insertion point is in the most hideous location possible; on the left, near the flywheel, behind the cross member, close to the engine mount and for good measure covered up by the auxiliary cooling pump. Also limiting accessibility are the power steering cooling lines, the A/C compressor, the engine oil heat exchanger and associated hosing and piping. It is virtually inaccessible and I have my doubts that any installers use the crank locking pin.

Audi does however provide a mark on the lower timing belt cover that lines up with a mark on the vibration damper/ribbed belt pulley on the crankshaft. It is these that I used to forgo the installation of the crank locking pin.

One should perform this procedure at their own risk and the writer assumes no responsibility for any adverse outcomes that may occur. Further, it is assumed that the crank and cam positions are relatively close to their index points and are only a very few degrees (say ±5 crankshaft degrees) off. The writer does not know how many degrees “off index” can be tolerated before the pistons interfere with the valves.

There are many excellent guides and write-ups out there that deal with the rest of the procedures and I am only going to set-out a procedure for final indexing of the crank and cams based on the use of the timing belt cover and vibration damper pulley marks. Starting at the point where the cam gauges (locking tools) are still installed, the upper timing belt covers are still off, the ribbed belt is installed and the cam bolts are loose but the cam pulleys do not wobble on their shafts:

1. It is important that the cam locking tools be tightly engaged to the cams so as not to permit movement. I set them onto the cams and while tightening the spreader rod I jiggled the tools axially back and forth to permit them to fully spread the roots of their jaws on the cams. It is also important the tools be of sufficient strength to resist the torque that will be exerted on them as they will see about 1,800+ pounds of force resisting the 75 ft lbs exerted by torqueing the cams. The Bentley book procedure describes torqueing of the cams with the cam locking tools in place so this does not vary from the “official” procedure.

2. If the crank timing is advanced then manually rotate the crank up to the point where the marks are aligned and stop. If you overshoot then proceed as if the crank were retarded.

3. If the crack is retarded then rotate it back past index marks about ½” or so then come back into the marks in the direction of crank rotation and stop.

4. Then proceed with the setting of the torque for the camshaft adjusters and then torque down the cam bolts all the time watching for any crankshaft and camshaft movement. For this, I went 15 > 30 > 50 > 75 ft lbs across the cams in the direction of belt travel and the crank remained motionless.

5. Pick up the other procedures from there.

In my case using these indexing marks resolved the misfiring and the engine was able to run smoothly.

All the best.