Blauparts has received reports of inadvertent damage occurring during the removal of the lower crankshaft timing belt pulley. Reassembly using even a slightly damaged pulley can cause catastrophic engine failure. Thus, we've decided to add the following information in regards to the lower timing belt pulley and front crankshaft seal.
Both Audi and Volkswagen engines have a lower timing belt pulley that utilizes a minimally sized ‘key’ (see illustration below). This ‘key’ is devised to engage with the corresponding keyway in the crankshaft. It's been reported that while loosening the main crankshaft bolt existing friction, corrosion rust, or stray thread locking compound between the bolt head and pulley can inadvertently twist the small ‘key’ completely off the pulley or cause damage beyond safe reuse. Additionally, because the ‘key’ engages just the tip of the crankshaft, the crankshaft keyway can also be damaged. Due to the possibility of this damage, the installer may want to contemplate the immediate need for the removal of the lower crankshaft timing belt pulley to access the front crank seal.
If there is no indication of oil leakage from the front crank seal, the installer may want to leave the lower crankshaft timing belt pulley as is, not risking damage. However, if the front crank seal is leaking and needs to be replaced, you have little option but to remove the pulley. Upon removal, it is crucial that you inspect the small ‘key’ protrusion found on the inside of the pulley for damage. You must also inspect the very front edge of the crankshaft keyway for damage. If the crankshafts keyway shows signs of damage and will no longer engage properly with the key on the pulley, short of complete replacement, it may be possible to locate a qualified welder and have the end welded up and ground to shape.
Blauparts has decided to stock the lower crankshaft timing belt pulley because of this problem (Item Number GG14000) and warns that by using a pulley that shows ANY signs of ‘key’ damage is unacceptable! If reinstallation is attempted with a damaged pulley ‘key’ or crankshaft keyway, the lower crankshaft timing belt pulley can easily fall out of time during main crankshaft bolt contraction, ultimately leading to catastrophic engine failure.