Watching valves through oil fill

[scratchee]

While breaking down my salvaged/spare A4, I was surprised to see that the valve stems were visible through the oil fill cap. Coincidentally, the A4 in my boat has started to make a rattling sound from the vicinity of the valve gallery (I'm suspecting a broken spring, but that's not the point of this post).

With the engine running, I looked down into the oil fill and had a clear view of the nearest valve in operation (meaning, the tappet and valve stem). Two questions: should the tappet be rotating freely back and forth? I think the answer is yes but I wanted to make sure. Second, has anyone stuck an inspection camera in there to take a look at the other valves (not too far, just enough to reach inside and sight down the row of valves)? With the engine stopped, this seems like a good way to check things out. With the engine running it's a little more interesting but also more risky.

[Dave Neptune]

Yes the tappets should rotate for even ware.

Dave Neptune

[Al Schober]

I suspect you're looking through the vent hole in the valve cover plate.
Late model blocks have the fill on the front over the flywheel. Early blocks have the fill back by the distributor.
As for the tappets, there is nothing to keep them from rotating.
I have one of those inspection cameras. There is an accessory tip with a mirror that allows you to look sideways. Always a challenge to figure out what you're looking at with that camera!

[scratchee]

I suspect you're looking through the vent hole in the valve cover plate.
Late model blocks have the fill on the front over the flywheel.

Exactly. I have a late model, and when I remove the fill cap over the flywheel, the first valve is right there! I never realized until I was doing a teardown on my bench.

[ronstory]

From the oil fill cap's perspective.