Rumbling Sound When Accelerating

[SFogg]

Greetings,

I apologise now if I have posted incorrectly; I joined the forum only a few minutes ago.

Recently (1 month ago) I purchased my 57 plate Mondeo Estate 1.8 TDCI (99,000 on the clock) from a small car dealership. Since then, the vehicle has been back to them on numerous occasions to fix issues that it should have not left the forecourt with - yes, I was mesmerised by the notion of saving a few quid and ended up buying from a bunch of cowboys!

Anyhow, I have recently noticed a 'rumbling' sound from somewhere in the vacinity of the engine compartment during acceleration. It appears to start around the 1500-1800 RPM band (in line with the Turbo activity), however I have been told by a Ford mechanic that it doesn't sound like a Turbo fault. The noise only presents itself when the engine is being loaded and cannot be reproduced when the vehicle is stationary. The noise starts off as a low rumble and increases in frequency as the RPM's increase. If I slacken off the throttle and cruise, the noise goes away. The noise is RPM related and not speed related.

All my previous vehicles have been non-turbo petrol machines, so I will admit now I'm no expert and would love somebody to tell me the noise I'm hearing is normal. Unfortunately, I don't think there is much hope of that though as I visited my local Ford dealership today and asked for an Engineer to accompany me on a short journey to diagnose the noise. I was told it definitely isn't normal and doesn't sound like the turbo. He pointed me at the air intake snorkel (for want of a better word) and told me their split design causes them to vibrate and I should cable tie the two parts together to stop them from vibrating. I must admit, I wasn't too convinced and not entirely surprised when I found the noise still there after following his instructions.

I understand describing a noise with words is near impossible, so I have recorded it using my Mobile Phone.

rumble.mp3

Can anybody please identify the possible cause of this?

Any help much appreciated.

[SFogg]

Just noticed the amazon price of £18.50 - no this is not a typo, it seems to have been added to my post automatically by the advertising software running on this web site. Actually paid 5k for the car!