To start this off - I'm not great on the mechanical side of things. I've been looking into an intermittent problem where at low speeds accelerating hard or letting off causes a 'clunk' sound - it's been getting worse recently so I've started to look harder into it.

Brakes look fine,

CV boots look fine,

Suspension looks fine,

Lubed up the anti roll bushing with silicone - noticed an improvement but with the intermittent nature of the sound I'm not certain it's actually improved.

I spotted a couple of parts which seem awful oily and I'm not certain they should be - and if not; if they might be the cause of this sound. Pointers appreciated! Car is a 2013 ecoboost 125. 

 

 

Are you asking what these parts are? Small square is highlighting where your driveshaft meets the differential. The big square is your oil pan.

How is your oil level? And is the other side of the oil pan also as greasy?

I would clean everything with brake cleaner (or anything like it) and then take it for a good drive. Then look again, should see where it might be leaking. From looking at this, it might be slightly leaking/sweating some fluid from the diff and the driveshaft is throwing that everywhere (I.e. the oil pan)

Also check your rear motor mount, the sound might be your engine banging against something when stepping on the gas. Let someone rev it and see if the engine moves excessively.

Hope this helps.

4 minutes ago, Roooney96 said:

Small square is highlighting where your driveshaft meets the differential.

This picture is offside, that's the intermediate driveshaft bearing, not the diff, so there can't be anything leaking from there.

Either way, that does look oily for a 5 year old engine, could be coming from various places though, sump seal (above the big yellow square) would be the first place I'd check.  It won't be the cause of the clunk though.  You say the suspension 'looks' fine, but did you actually test the ball joints with a lever to check for play?

 

 

Thanks both. All fluid levels visible from engine side are ok.  I don't think gearbox fluid is checkable though? 

13 minutes ago, TomsFocus said:

You say the suspension 'looks' fine, but did you actually test the ball joints with a lever to check for play?

 

 

Not with a lever did give it a vigorous shaking to feel for any movement. Car passed MOT without any advisories 2 months ago so I think they'll have checked it properly then? 

Gear oil isn't easily checkable no.  But that's almost certainly engine oil.

The MOT will have checked ball joints with a lever yeah, shaking isn't really good enough unless something is very broken.  As there were no advisories, it's probably nothing major though.  So would be worth checking the engine and exhaust movement as was mentioned above.