Pretty sure it's the accumulator. Noise is in the pipe, and up at the accumulator where it comes up from the pump/car underside, the pipe is almost dancing with vibration. You can feel 'turbulence' in the pipe when squeezed between your fingers. Nothing on the outlet side where it goes to the filter though, which is clearly a good thing. Amazed it doesn't have some effect on starting and running, but car is super sweet
For good measure, it's had a new pump non return valve and also an in-line filter from tank to pump
Anyway, new Bosch accumulator ordered from eBay. Easy job, so fingers crossed
Pic attached for good luck !
