vibration on 1.8 tdci galaxy

[Declanmcginn1]

Hi all, new on here. I hope someone can shed some light on a problem I have. I had a mk2 galaxy 1.9 tdi for the last 10 years and just recently upgraded to a mk3 1.8 tdci. It's a 07 Zetec with 118k miles. When driving in any gear there is a vibration which sounds like a loose exhaust coming from around the passenger footwell. It starts at around 1800 rpm and continues until about 2100rpm. Before and after these revs it is as smooth as silk. When stationary, the vibration disappears and cannot be heard at any revs. I have checked around the area it seems to be coming from but can find nothing loose. It has me stumped. Any ideas? 

[insanitybeard]

If it is only occurring when the vehicle is in motion then it could be driveline related. Does the noise/ vibration change or disappear if you push the clutch in (therefore taking the load off of the transmission and driveshafts) when the vibration/noise is occurring? 

[Declanmcginn1]

Sorry for the delay in replying. The vibration stops immediately on release of the throttle, even before you get to dip the clutch. It then returns instantly on accelerating through the before mentioned rev range. It seems to be more pronounced when pulling on from low revs in a higher gear. The clutch was replaced about 10,000 miles ago, I'm unsure about the flywheel (but I very much doubt it...) TBH I think the vibration sounds too light to be drive-line related and there doesn't seem to be any feedback through the controls, (e.g. steering or clutch pedal). It sounds like tin plate vibrating as air passes over it ( a kind of rasping sound). I've checked all the heat-shielding underneath and nothing stands out as an obvious cause. I'm strongly swaying towards a loose baffle in the exhaust box. If this proves negative, I'm well and truly stumped.Thanks for your suggestions.

[insanitybeard]

It could be resonance in something or like you say exhaust related, but if it was I'd think it might happen if you just rev the engine to the approximate speed at which it normally happens with the vehicle stationary- which you say it doesn't do, unless it requires the the vehicle to be in motion & the engine under load to produce an increased exhaust pressure to cause the noise.

[Declanmcginn1]

Thanks for your input. It's still under investigation. I'll post an update when I know more. Cheers