My Mondeo Mk4 2.0 TDCI which I bought from a Ford dealer around 2 weeks ago has developed a strange problem only the last three days.

When I start the car first thing in the morning the engine at idle sounds much louder than usual. It sounds almost like the older Ford TDDI engines or an older Passat TDI. I have a 20mile trip to work and by the time I get there the engine sounds almost back to what it should sound like.

The DMF has been changed by the previous owner and I can tell there's no issue there but there is some sort of a deep grumbling sound coming from the gearbox area or around there when seated in the car but can't really be heard from outside.

Car seems to be driving the very same and has good power.

This only really seems to happen when I start the car first thing in the morning...in the afternoon or throughout the rest of the day engine at idle seems relatively normal.

Up until 3 days ago when this began engine was very quite upon cold start up.

Any suggestions what this could be or what to start checking for?

same thing my mondeo mk4 only i get noise from front of car thought it was exhaust but after driving to work engine quiet again

Yeah it's very strange...seems to only happen on initial starup and then gradually fades out