Hi new here and first post , I have bought a second hand Octavia 1.2tsi. Sounded grand test driving it around town but when I was coming home on the motor way I can hear an oscillating pulsating sound which goes up in pitch when I speed up ,also it seems to disappear when I'm coasting even at speed so it's just when it's in drive like pushing , any ideas would be great, thanks ! Hope it's just a bearing as they look easy to fix , but they are hard to diagnose ,and with the sound disappearing when coasting I'm not sure....

Try going round in full lock circles in an empty car park. If you hear knocking it's safe to say the CV joint(s) are shot.

 

Just thinking out loud as a wheel bearing would be a constant sound whereas a transmission component may manifest itself only under load.

Yea I'm thinking the same ,it's related to wheel speed and only happens under load and when coasting it disappears and its nice and quiet, bearings can be funny things though, hope I haven't bought a lemon, it's ok going around corners no knocking or anything . Hmm to the garage I think only had it a week ,luckily it's under warranty, I just want to have some sort of idea before I hand it over.

Ok so brought it back and he had his guy check it ,said he had it on the motorway doing 110km and no sound ,and I was like really ? He said it was fine ,so i collected it in rush hour traffic ,and drove it home ,and the noise is still there ,a helicopter noise when under load, no really tire noise and no bearing noise when coasting, even with it in gear and clutch down, Or out of gear, it's quite loud so his guy must be deaf, I can hear it over the stereo and fans ,!! Anyone ever heard this !thanks.

Sounds like inner CV joint.

Would that only make a sound when under load, or would it be spinning in neutral too ?it's related to wheel speed alright as when driving in 1st up my drive it's a slow low pulse,and when at speed it's quite loud and fast. Transmission Input bearing would be down to engine speed wouldn't it?Thanks for your reply!

Rear tyre sawtooth wear ?

Edited 16 March, 20188 yr by bigjohn

Plus 1 for inner cv joint, if you can get under the car and twist the drive shafts by hand you should be able to detect any play in the joints,

Front wheel bearings normally make a droning noise, can you find a road with long sweeping bends as bearings will change the sound they make as the loads on them change.

I had the same kind of noise and though it was the rear wheel bearing but it was a rear tyre . It sounded as a rear diff was worn /dry. I know they don't have a rear diff but it was that kind of noise.  It disappeared when I had a puncture on that wheel. I think it was the tread pattern on a certain kind of road surface.

Edited 17 March, 20188 yr by erindad

14 hours ago, erindad said:

I had the same kind of noise and though it was the rear wheel bearing but it was a rear tyre . It sounded as a rear diff was worn /dry. I know they don't have a rear diff but it was that kind of noise.  It disappeared when I had a puncture on that wheel. I think it was the tread pattern on a certain kind of road surface.

 

As I mentioned above - rear tyre saw tooth wear is very common on independant rear suspenion VAG cars. If you want to prove without spending money swap wheels front  to rear and rear to front - which will change (obviously not cure)  the noise if it is this

Edited 17 March, 20188 yr by bigjohn

But wouldn't this be a constant noise , this drone is only under load and disappears when coasting. I'm going to check drive shaft I think, hopefully it's a bolt on part like that and not something internal! 

6 minutes ago, Sino23 said:

But wouldn't this be a constant noise , this drone is only under load and disappears when coasting. I'm going to check drive shaft I think, hopefully it's a bolt on part like that and not something internal! 

 

When I experienced this it was a swine to diagnose and the noise did change on how you were driving. Just try the swapping tyres around to see if it changes before you start on the path of chucking lots of parts at the problem.

 

Any warranty on the car? - [EDIT] just saw it's still got warranty - take it back!

Edited 17 March, 20188 yr by bigjohn

Yea brought it back he fixed a crank case valve issue ,just a broken little plastic bit , but surprise he said he couldn't hear the noise , I think I'd have to bring him out in the car to check it, the saw tooth issue would be constant wouldn't it and not depending on accelerating in gear.

I'm leaning towards output bearing now , I had the car up on Jack's and stands and it sound rough like very dry bearing or something when in any gear and all related to drive shaft speed ,quite when spinning by hand no rough spots or anything,anyone had this?

How many miles has the car done?

Did you try turning the drive shafts backwards and forwards to see if there is any play in the inner joints? 

122000km so about 90000 miles. I'd be a lot happier if it was a drive shaft and not a gearbox bearing alright , yea the shafts seemed tight enough no obvious movements.

1st gear ,it's the high pitched grinding dry whirring noise .

VID_20180319_130213093.mp4

That won't open on my phone... But I'll swing you in this direction.. Wouldn't be an alternator pulley would it!?

Does sound bearing like but could still be inner CV, also is that a rusty hole in the wishbone?? You might want to get that sorted.

Woah I didn't see that I'll have to have another look, well spotted t2000!

Well it's been at the garage it's a gear box refurbished job dealer has offered my money back I'm going to take it and run !

Was the wishbone rusted?

Wasn't sure had a quick look and it seemed it was a shadow or something, anyway problem solved car is gone only after two weeks full refund ,it's someone else's problem now , was looking at a 2011 1.6 octy now , at least I know how to spot a dodgy gearbox now. Are the dpf failings luck of the draw ?