TD5 Discovery noise

Hi All.
Just as I thought i'd got her running right its at it again. (I was warned about landrovers needing more attention than the woman)
the problem now, is that when the engine is turned off it continues to make noise on and off for about 30 secs. The best way to describe it is engine off.....grrrrr. 3 secs grrrrr. 3 secs grrrrr etc.
To me it sound like something is spinning and slowing down but I couldn't pinpoint the noise, My first thought was the turbo or the fan but i couldn't tell for sure and the noise doesn't happen every time.

has anyone else come across this or have any ideas. Thanks.

If it's like mine it is the air suspension 'going to rest'!

I had thought of that but i've converted mine to springs. the compressor is still fitted but all the wiring is disconnected. or at least I think it is.

Well, I tried! I'm sure someone who knows will be along soon.

Think it is compressor for air bags mine did it before I changed them check it is disconnected

Obviously new to TD5s. It's the rotary oil filter winding down

I'd have mentioned the rotary oil filter, but the 3 second pauses are at odds with the filter; it just tends to spin down in one go. At least it does on mine.

Diff.

I never heard the rotary filter stop then start again after 3sec