Knocking/Rumble from footwell when engine under load

[afstcklnd]

My 2010 W212 (I believe) E-Class estate with the M651 engine has a knocking/rumbling sound which is mostly coming from the left hand side footwell area when the engine is under load. A faint version can be heard when the engine is idling. Outside of the car on ramps, the noise is not so evident underneath the car or under the bonnet.

There is some vibration back through the clutch pedal but it doesn't seem to be transmission and I don't think it's timing chains.

The exhaust runs down the right hand side of the car and there doesn't seem to be anything on the left hand side.

Any ideas or advice?

Thanks in advance!

 

[A.J.]

Could be exhaust loose could’t it.

 

[afstcklnd]

Could be exhaust loose could’t it.

Hi - thanks but tried that and all solid
A

 

[A.J.]

The only other thought was prop shaft but then you wouldn't get it on tick over

 

[pgh13]

Engine mounts? If you chock the wheels, rev the engine and slip the clutch does the engine noticeably move?

 

[Doug1234]

Stick both right hand side wheels up on a high kerb with engine running to load the left hand engine mount and then do the same with the left side wheels up to check the right side .
If a mounts gone you should be able to feel it wobbling at tick over, certainly did with my old w124 diesel

 

[brandwooddixon]

I'd be inclined to suspect engine mounts, especially if the rumbling is worse when the engine is under slight load.
A prop-shaft mount or bearing typically shows up when the transmission is under load such as when moving off from a standstill.
I suspect that your car may have oil filled engine mounts, these are prone to perish and leak. The replacements are more expensive than some pattern parts, but well worth the extra cost.

 

[afstcklnd]

Yes, oil filled engine mounts but they seem OK tbh. No noise from the subframe and no real movement for the 'load' tests

 

[oigle]

Hard to diagnose by looking at them. You will be amazed at the difference a new set makes....

 

[ajlsl600]

Engine mounts? If you chock the wheels, rev the engine and slip the clutch does the engine noticeably move?

2nd 4 mountings.

 

[afstcklnd]

Recording of short trip if it has.

Sound seems to be coming from inside a black panel on bottom of clutch housing.

 

[afstcklnd]

Diagnosis is 'flywheel dampers breaking down' - will update after they take it all apart next week.
A

 

[afstcklnd]

Final situation: Inconclusive

Definitely not engine mounts or exhaust or similar.

Flywheel was replaced but no clutches available at the time and the one installed looked OK. Post 'repair' it was almost worse that it was before. Garage messed around with exhaust linkage but no better so I returned the car and got my money back.

Suggestion was that either the clutch was also faulty or the flywheel issues had damaged something in the gear box.

Anyway, outcome OK for me and I bought something else.