Technical 2011 - 1.2 Lounge with loud engine reverberation / clunking

[ACRO]

Hi folks,

This is a difficult issue to explain but our 2011 1.2 Lounge (~40k miles) makes a loud reverberation/vibrating noise that is mostly heard at low revs under load, and worse when turning. Seemingly also only when the engine is cold. The noise almost sounds like the engine is vibrating off it's mounts. I can reproduce the issue with the front jacked up, tyres off and lifting the clutch into 5th to simulate load (with the engine running, of course).

I've been trying to fault find this afternoon and cannot put my finger on the issue. Wheel bearings seem fine with no play, all 3 engine mounts also feel okay when tested with a pry bar, all suspension components look OK (bar some rusty top mounts). CV joints also look OK, a little gearbox oil weeping on the N/S boot/axle but no signs of the boot itself leaking.

Any suggestions on where to look next?

 

[steveras57]

Just wondering if this might be signs of your gearbox layshaft bearings stating to fail! \.
On mine it was mostly in first gear (where theres the most torque!) but i also got noise kinda like a "drumming vibration"(though less noticeable because of wind noise when moving faster!) in both 3rd and 5th!..

Strangely when the gearbox was removed the play was kinda like increased end float at the output shaft rather than any lateral movement!, the clutch was also "cream crackered" thought the car was driving fine and shifting gear ok too! only symptom at that stage was the noise, but glad i did it then as i guess it could have turned into a grenade at any time!.

 

[A3jeroen]

Alternator bearing Ok?

gr J

 

[ACRO]

Thanks both for your inputs. I managed to get a video (with the help of a trusty assistant), you can mostly hear the rattle on the first and third attempt.

 

[steveras57]

To be honest dont sound anything like what mine did so inclined to think not the same problem does sound drivetrain related though, to me at least maybe a mechanics stethoscope might help pin the noise to a more specific area!.

 

[steveras57]

Hi any progress in pinning this down ?.

 

[Ralf S.]

My guess is that one of the inner CV joints is knackered or the clutch is on borrowed time.

You can check the CV bearings for free. Hold the inner CV/cup steady and then try to rotate the driveshaft itself. There should be zero movement. If the shaft has some "slack" in the cup then you need to have a look inside.

Detach the driveshaft outer end from the suspension, remove the CV clip from the gaiter/cup and pull out the driveshaft.

Have a look at the orbital bearings (there should be three rings mounted at 120-degrees). If a load of metal falls out, or there are loose needle bearings in the grease that's not a good sign. Each orbital bearing should obviously be intact, no marks and no needles all over the place. You can also "feel" inside the cup for debris or bad grooves worn into the cup.. although at your mileage this should be negligible. Note there are machined "slots" for the orbital bearings, which is normal.

Make sure you have a spare CV boot clip and some CV grease before you open it up... so you can put it all back together again afterwards.

While the driveshaft is out of its cup, have another listen for the noise... obviously staying out of any rotating parts. Stick some cling film over the cup to stop grease flying out.. but then put your head next to the gearbox. If it's a scraping sound then I would look at the clutch as the likely culprit.

Worst case scenario is that the gearbox input shaft bearing is moody.. but to find out and fix it, you need to take the bell-housing off anyway, and if you do that it makes sense to fit a new clutch kit; 40k is likely the original and they don't make it much past 60k without getting grabby, even though the friction plate still has a way to go. So.. go in with a new clutch kit but examine the bearing once the gearbox is off, in case it's that instead/as well.

Ralf S.