Could be a very noisy Disa valve?
I believe to check this, simply unplug the Disa connection & try it.
Alternatively just remove the Disa valve itself, fairly simple job anyone can do.
If I am hearing right, mine makrs a similar noise, although I have been told its nothing to be concerned about. I too have refurbed the disa and intake pipes so would be interested to know how you get on!
Its difficult to tell from that clip but going off your description of dry cogs Id be tempted to say either the water pump or one of the pulleys/air con at the front etc
Its difficult to tell from that clip but going off your description of dry cogs Id be tempted to say either the water pump or one of the pulleys/air con at the front etc