Audi 2.8 B5 SOHC Timing Belt Breaking

Below is a video that shows some of the issues that arise when the timing belt brakes on a interference engine. It also covers the notorious cam issue the SOHC 2.8 engines experience. Lobes will literally wear down to nothing if the improper octane is used in the engine over a long period of time. This will cause one or more valves to not open completely leaving the engine down a cylinder. Over time the metal shavings that were worn off will cause damage to the oil pump, leading to catastrophic engine failure....not to be negative... Catch it soon enough and change the cam, lifter (follower), and oil. The sound should sound like a tapping similar to lifter tick, but it isn't lifter tick... Simply pulling off the valve cover will give a clear view if it is a cam issue. If it is the Cam, replace and it should be good to go...unless you have been running WOT for long periods of time or are actively participating in street racing.

Audi Timing Belt and Camshaft Issues