Weird Noise From Engine

[DocBrown]

My 1997 1.9 TD SX hatchback has started to make an unusual sound when driving. It happens if engine is hot or cold, short journey or long run.

Specifically when either coasting down a hill or lifting off the throttle or on over run, there is what I can only describe as a low growl from somewhere under the bonnet.

A growl is the only way I can describe it as my wife thinks it's more like a cat purring albeit for a few seconds. Very occaisionally the engine management warning light (top left of instrument panel) will come on for a few seconds then go out. It doesn't do this with the noise but the lamp does come on when lifting off the throttle or changing down a gear. (yes, I have made sure neighbours cat hasn't climbed under the car to warm up)

 

I've not heard this sound before on my XM or other Xantias I have driven.

 

Any advice please?

 

Cheers

Doc