SO let me try you vintage folks. I have 2 1983's one with 100 hp and one with 160hp. Both mechanical lifters. The 100 hp I bought with 83Kmiles and now it has 130K miles. I never had the valves adjusted. The make a light ticking noise. The 160hp - I can't say for sure how many miles that one has.
Can it be told by sound if there is too much play and damage is about to occur? What kind of damage occurs if there is too much play?
Any tips - I do know a bit on how the shims are replaced. I once tried to measure play - but by the time I got the valve cover off things cooled off.
steve

Steve,
Have you tried running an engine flush, or other treatment product (like Marvel Mystery Oil) in the engine? Ticking is annoying, but I doubt that serious damage would be caused by it - if anything, you may get a bit more wear on the lifter shims. Check the tops of the shims for wear - I imagine that the cam lobe would wear by just as much as the shim surface would.
Is this a 4k we're talking about? The ticking isn't the vacuum pump rod, is it? (probably not, just asking).
Cheers!

The adjustment of the lifters is spec'd cold. Therefore when it gets hot, then the adjustment is appropriate.

Since the adjustment is via trimming the shims, you don't have anything to do really. As they wear the play gets greater. The only thing you could do is buy new shims.

Ticking isn't going to do anything, no harm other than making noise. It will affect performance a bit since the valves aren't opening as much. But it's relative, you are after all looking at a motor that's 23 years old and only started with a modest amount of HP.

What's worn is the shims, the valve stems and the profile of the cam. You can take up some of the wear with new shims and then grinding them down to spec. It's unfortunately a tedious process. You need to measure each valve and make notations. Then take it all apart and grind each shim the coressponding amount. Then you need to reassemble and check it all over again.

Not a fun job. Nor was it one of Audi's better ideas. It's great for high RPM and high lift cams like in mine. But, you need to take the bad with the good.

If you're up for it with a cool engine measure the clearance and go at it. If you don't want to tackle it, it'll be fine as long as it isn't horribly off.

If you first check when cold.