On 14th September 2011, I decided that I would give Sentinel 7109's engines a little exercise on compressed air. They are still not connected to the front axle as the chains have not yet been fitted and so running them on air is quite easy.
For the first video, I set up a tripod on the Midsomer Norton Station platform and pointed it at the leading engine's open cover; the result follows: (Also on YouTube)
There are some interesting noises. The clanking is the knocking together of the substantial gear teeth without any load to hold them in contact. A creaking noise seems to be one of the valve springs compressing. The regular hisses are the four valve pairs opening in turn; the fact that the sound is consistent for all four is a good sign.
To get nearer to the engine sounds, I then set up the camera with two of the tripod legs on the nearside running board on the of the loco. Little did I know that the engine would shake everything in sight including the camera. So apologies for a little fuzziness but it hasn't spoiled the detail. Can you tell whether the inlet valves (LHS) open and close at the same time as the respective outlet valves (RHS)? (Also on YouTube)
I did say Shake, Rattle, Roll and Clank. Pretty close to the mark!