Louder knocking noise from engine

[tyberwan]

Hi

Today after a short drive, I noticed a louder knocking noise from the engine. It seems that the normal noise in the morning, like the "click click" of the engine in the morning on start up, has become a little bit louder. But on revving up, it goes away. On driving as well at higher revs, you do not hear it. It's only when the engine is running when car is idle.

I checked my oil level - which was below the bottom mark, and topped up again. Oil lights yellow or red, never came on. Pressed the check button but everything else fine.

One thing I find strange is that several occasions, a week after I checked that the oil level was perfect, the level goes below the minimum mark (after a week). How could it consume so much oil within a week? There is no oil loss on the floor, nor a lot of smoke when accelerating.

Thanks

[tyberwan]

Another thing which comes to my mind. If a valve or a tappet (is it the same thing?) is broken and cause this sound, would the system not shut down automatically preventing more damage?

I once had a Golf 4 Year 2000 and one day driving on the highway, it shut down as if I ran out of fuel. Result - a broken timing belt. The car system apparently switch the engine off to prevent more damage. I only had to change valves and timing belt.

Would it be the same in A4?