Polo 2010 6R 1.4 Petrol - Possible Gearbox Issue

[Nighthawk265]

Hi all. New member here looking for some advice please. My 2010 VW Polo 6R has developed a knocking/whine noise coming from the front of the car. It becomes more frequent as speed increases. It very much sounds like a hub bearing fault, but don't think this is the cause. Car also vibrates inside the dash when driving, getting worse with speed.

We have changed the both front hubs with new bearings. Also tried eliminating unbalanced tyres/wheels by moving front wheels to the back on both sides..issue still remains at the front of the car. Still no sound or vibration issues at the rear.

Sound is the same whether in gear (forward and reverse) and out of gear, clutch in or out. Gets more apparent with speed

Tried raising front of car up and running the car in gear. No loud sound (but this is likely to car having no real weight/load on the drive shaft). Also, the ECU seems to limit the speed to around 10mph due to mismatch from the wheel speed sensors, so couldn't really get the wheels turning any faster, to try reproducing the sound.

There is a slight knocking sound coming directly from the gearbox. This was heard with the engine running in gear, while car raised up. Can also feel a very slight tap (around 4 times a second) while wheels turn in first gear (around 10 mph) from the gearbox

Gearbox checked and has plenty of oil. Right up to the level of the plug. Oil nice and clean too, so no evidence of damage.

Didn't take off the boot covers on the drive shaft fully, but seemed to have a lot of that black grease in them, so looks like these are not dry.

Does this sound like a gearbox issue? Or maybe some drive shaft/gearbox bearing? Can anyone shed some light on this please?

Any recommendations on what I can check? Planning to take it to a gearbox specialist and let them test drive and see what they think, but want to rule out any easy-ish fixes first

Many thanks!

[iichel]

What about a CV joint?

[Nighthawk265]

Yes, seems possible. Might be resonating onto the gearbox from the CV. Is there a way I can prove this, without swapping it out? Both sides of the CV had their boots secure and not split. Seemed full of grease too. That's not to say they might have internally worn

Also, no change whether straight or turning

It is the front left of the car, that the sound seems to come from. Think it's the shorter of the two shafts

[iichel]

It's difficult to judge via the internet. I'd suggest to go to a workshop. If it's an inner CV joint for example, it can still rattle properly without losing lubrication.

[CarbonChaos]

‘There is a slight knocking sound coming directly from the gearbox. This was heard with the engine running in gear, while car raised up. Can also feel a very slight tap (around 4 times a second) while wheels turn in first gear (around 10 mph) from the gearbox‘


Could this be diff bearings ? Is there any movement if you wiggle the shafts up and down ?