4Driver4

If the cam is an issue, you'll know immediately.
True. Later is better.
Then why are you pulling the head?

old96A4

The car has a loud ticking sound, thinking it's a bad valve. Tryng to figure out if I want to try fixing it or not. The worse case would be to have to pull the head and replace valves..


question on another topic: when I stand in front of the car which O2 sensor is downstream left ?? passenger side? or am I in the car which would be drivers side?? how does the manufacture define them? have a bad O2 sensor in bank1 01 on My current A6 I think.. thanks

4Driver4

Have you done a leakdown test? That would be the way to determine if a valve is bad. You would have to remove the head to change a bad valve, but never to diagnose a bad valve.


In the US, left side is driver's side; right and left are determined as if you are standing behind the car, not in front. Bank two is right side.

old96A4

No sorry not familar with the leak down test, Is there a write up some place??
explain, I assume it tests how long the compression stays in the cyinder? Is it just using a compression tester?? But if I have a ticking something is wrong with either the CAM or the valve I would think. If it leaks I would think the timing would be off only..

4Driver4

A valve is a simple thing. There isn't much to fail. It can be either burned or bent. That's pretty much it. In either case, a leakdown test would show that (not to mention that you'd be misfiring and throwing a CEL). I can't imagine how a clacking noise would be a valve.

To learn about leak down, try a google search. You have the basic idea, but a leakdown test is more than just *if* there is a leak, it is very helpful in determining *where* the compression is going.

jcman

4Driver4 is right on with his comment^^^^^^^^

If you hear a clacking noise the most simple logical step would be to pull the valve covers and check all the cam lobes for wear, hell use a wooden stick or 1/2" PVC up against your ear to locate the source or VC side and go from there.