Seriously, a rattlesnake is the only description I can give this weird noise that is only audible from time to time, mainly on days when the DSG gearbox's grinding symptoms come back in 1st and 2nd gear. The rattlesnake noise is like a ticking sound that increases in volume then decreases, over the space of a mere few seconds. It sounds like it's coming from the nearside of the engine bay and it happens under acceleration, not from a standstill but when giving the car a bit more beans whilst driving e.g. accelerating from 40mph to 50mph then backing off the throttle. Any ideas?

What engine do you have and what mileage? Has the DSG had its oil changed at the 40K intervals?

 

I see why you are thinking about the gearbox but I have heard similar sounds from failing Dual Mass Flywheels (DMF) on diesels under the conditions you describe.

Apologies, I should have said. Mine's a 1.8 TSI 7-speed DSG.

My money is on the Dual Mass Flywheel - don't leave too long before getting it checked and doing something about it, you don't want it to catastrophically fail and write your gearbox off. 

A friend of mine has just scrapped a reasonable Mondeo after a DMF failure did some major damage