Input shaft bearing noise?

Sylvester

Sylvester

Member
Hi all, my 1.4 petrol makes a whiny bearing noise, sounds it comes from the top area of TB. Not too loud for now, but can be heard when idling and gets louder when speed increases. But as soon as I barely touch the clutch, like 1/2 inch, the noise goes away. Could it be still TB or it probably input shaft bearing?

The clutch kit had been changed around 2 years ago, had cost £550 with a mobile mechanic. Could they have under torque something or the clutch kit has not much to do with the bearing?
Any experience how long can it go for, and what happens when the issue gives in? Thanks
 
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In my experience, any bearing noise that is affected by pressing the clutch is usually the Thrust Bearing.

Now my TB query will make more sense to you!
 
TAABVW said:
In my experience, any bearing noise that is affected by pressing the clutch is usually the Thrust Bearing.

Now my TB query will make more sense to you!
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Yes it does. But far as I know, thrust bearing makes noise when clutch is depressed, but I get the opposite, so no noise even to slightest touch of clutch. Hence I think it's input shaft bearing, which may make the noise due low gearbox oil level? Or those 2 aren't connected that way? Cheers
 
Yep, you could be right.

My logic is as follows. The change in force on the input shaft and hence shaft bearing from pressing the clutch pedal a little should be tiny both axially and tangentially and you would not have disengaged the clutch yet. The change in force on the thrust bearing axially from pressing the clutch is huge by comparison. I agree that bearings normally make more noise under load but not exclusively so. The only other thing that changes when you slightly press the clutch is the clutch switch (if the petrols have one). Perhaps you could get down into the foot well and press the clutch switch without pressing the clutch pedal, this might tell you if your noise is coming from somewhere other than the bell housing.
 
TAABVW said:
Yep, you could be right.

My logic is as follows. The change in force on the input shaft and hence shaft bearing from pressing the clutch pedal a little should be tiny both axially and tangentially and you would not have disengaged the clutch yet. The change in force on the thrust bearing axially from pressing the clutch is huge by comparison. I agree that bearings normally make more noise under load but not exclusively so. The only other thing that changes when you slightly press the clutch is the clutch switch (if the petrols have one). Perhaps you could get down into the foot well and press the clutch switch without pressing the clutch pedal, this might tell you if your noise is coming from somewhere other than the bell housing.
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Noise definitely coming from the area of throttle body, could be lower, but definitely that section of the engine. What I'm trying to figure out first of all, can low gearbox oil level cause this noise, as the input shaft bearing isn't lubricating enough, or those aren't close mechanisms? Cheers
 
If the bearings have been exposed to low oil for a while or water contaminated oil, there is a chance the bearings themselves could now be damaged. Prepare yourself for a gearbox inspection or replacement....
 
audifan said:
If the bearings have been exposed to low oil for a while or water contaminated oil, there is a chance the bearings themselves could now be damaged. Prepare yourself for a gearbox inspection or replacement....
Click to expand...
I've had a look and the gearbox oil had been changed just a year ago, but this low whining noise started like a month ago. As soon as I apply 1 inch pressure on the clutch, the noise goes away. I'm not sure what causes it, but I'll add 150 ml oil to the gearbox and see how that changes. Thanks
 
I've had this problem with a Golf box. Drop the gear box oil and check for metal debris, I found them. Keep it clean and it can go back but for the price of 2 lt I would put new in.

Steel can be detected with a magnet. Alloy or white metal will give the oil a silver grey appearance. If no metal the chances are the bearings in the box are still good, look for less expensive to repair causes.

If you find nothing elsewhere, you may need to revisit this. My A2 box has many ball bearings dropped in it that cause no problems, so I suspect there is a magnet in there somewhere that will collect steel debris until it becomes overwhelmed, as there is and it had in my Golf.
 
philward said:
I've had this problem with a Golf box. Drop the gear box oil and check for metal debris, I found them. Keep it clean and it can go back but for the price of 2 lt I would put new in.

Steel can be detected with a magnet. Alloy or white metal will give the oil a silver grey appearance. If no metal the chances are the bearings in the box are still good, look for less expensive to repair causes.

If you find nothing elsewhere, you may need to revisit this. My A2 box has many ball bearings dropped in it that cause no problems, so I suspect there is a magnet in there somewhere that will collect steel debris until it becomes overwhelmed, as there is and it had in my Golf.
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I'll have a look, sounds like the next thing to check, thank you.
 
audifan said:
If the bearings have been exposed to low oil for a while or water contaminated oil, there is a chance the bearings themselves could now be damaged. Prepare yourself for a gearbox inspection or replacement....
Click to expand...
Good afternoon, so I'm in the middle of changing/checking the gearbox oil. Is the 1.4 aua petrol gearbox oil capacity is the same as on Tdi, so 1.9L?

Ive had 1.4L coming out, but Ive read 400ml could be traped among the gears and cogs. Which would make it almost proper amount. Is that true though? Thanks
Thanks
 
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Sylvester said:
Good afternoon, so I'm in the middle of changing/checking the gearbox oil. Is the 1.4 aua petrol gearbox oil capacity is the same as on Tdi, so 1.9L?

Ive had 1.4L coming out, but Ive read 400ml could be traped among the gears and cogs. Which would make it almost proper amount. Is that true though? Thanks
Thanks
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Did you warm it up and leave it until it stopped dripping? There will be very little left. Even if you drained it cold there will be very little left. I’ve never worried about this and just pour 2 lt into my TDi box.
More interesting is; what condition is it in?
 
philward said:
Did you warm it up and leave it until it stopped dripping? There will be very little left. Even if you drained it cold there will be very little left. I’ve never worried about this and just pour 2 lt into my TDi box.
More interesting is; what condition is it in?
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I've drained it cold, but it was flowing nicely, and waited till it was dripping very slowly. I've had a look and couldn't find the exact amount for petrol's gearbox oil, so I went with the diesel 1.9L. On the ramp after drainage, I've added around 1.6L till full, and 0.2L through the reverse light switch. The 1 year oil was dark, but still showed golden glow in a tube, I've also added 1L brand new oil, rest was filled from older amount. I've actually drained it 2x, and there was no trace of any metal debris. I'm gonna check tomorrow if that bearing-noise still there.

I've also found out the location of the clutch-spring noise, but I'll start a new thread for that. Thanks.
 
I was about to go to work, but it felt the engine was shaking a bit?! I turned it off right away. Could I have over filled the gearbox and cause this? When I reversed down from the ramp, all seemed okay, but it wasn't leveled maybe and now it over filled? There's not supposed to be more than 2L. I gotta get the bike out now :/ Cheers
 
So after work in the afternoon, I'd tried again and the car doesn't even want to start now...
If I crank it long enough it fires up very slowly, but the idle is too high, and sounds like a tractor. It's been driving absolutely fine, yesterday too, but now it's almost dead. No warning lights on the dashboard.

Did I flood something when filling the gearbox?? I'd topped up 1.7l from top hole, then around 0.2l through reverse light switch, which should be this one on the picture, or and am I wrong and filled the wrong location?
Screenshot_20231124_150045_Gallery.jpg


I didn't work on anything else electric yesterday, only unplugged the reverse light connector, removed the switch, then after filling I plugged both back.
I had to wiggle the undertray to go back in place, could I have damaged some wiring down there, that caused this?
Oddly after that the car fired up without hesitation and drove off the ramp too. But now it's nothing.
The only fault code I don't recognise is: 01336 Data Bus for Comfort System sporadic: In one -wire operating mode.
But I'm not even sure it has anything to do with the current issue.
The whole thing feels like flooded engine or similar...Any advice? Thanks
 
I really don't know what to do. I'm moving house in a week, so the timing is really bad.

Shall I try to start the engine by cracking and pumping the gas as long as necessary, then just let the idle go haywire until the system throws a fault code?
 
If you have still got the oil that came out check the volume. Compare it to what went in just to satisfy yourself. Slight variations either way will make no difference. Even if over filled slightly I can't see how the box will stop the engine running. Press the clutch to decouple the box and see if the engine runs.

I’m no A2 petrol expert but it sounds like a sensor failure on the engine.

Edit, a further thought, it didn't come to mind because I don't do this. There is as far as I know there is a fill / level plug; on other VW vehicles I have taken this out to check the box oil level. Could be worth Googling A2 box oil level check and giving it a go.
 
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