Tdi 1st gear noise when breaking

[xpro]

Hi all.

My 06 Tdi 150 developed some weird noise today. 65k miles, well looked after car, im not a hard driver.

Gearbox appears to be very smooth, no bangs or rattles, but when downshifting and engine braking, only in 1st gear, i get this horrible whine, grinding noise as if the clutch plate is sort of slipping and making noise when the friction starts. It only happens when going into first gear when engine is braking.
All other gears are fine, no whining and no juddering.

I dont know what is going on.. I changed the gear oil a few months ago, clutch is not slipping. Maybe DMF? Even do it doesn't sound like the dmf is gone..

Any ideas please?

Thanks

 

[xpro]

Just a quick update:

The noise nearly stops and can not be heard when the car is hot.
Also when driving in the reverse gear, there is no noise.

It only happens in first gear, and only when deaccelerating from 2nd gear.
Acceleration in first gear are fine, no noise..


Help appriciated!!

 

[BigJase88]

Gearbox main bearing starting to wear! Mine whines like a good un when decelerating in every gear :O

Try a gearbox fluid change to see if it helps

 

[BenG]

I get a slight whine decelerating in gear in my car too. Worn bearings seem to be an issue with the 6-speed gearbox.

I guess engine braking in first will put greater stress on the 'box than using higher gears, so maybe avoid that OP?

Is it advisable not to use engine braking in gear but just knock the box into neutral and just brake?

It does mean not being able to take advantage of the overrun fuel cut-off, but I guess it's cheaper than a 'box rebuild...

 

[xpro]

Thanks for the replies.

It does sound like a worn bearing indeed. Only starting to go as it can be only heard in first gear.

Im very fussy and i hate driving the car like this, so i will take the box out hopefully this weekend and go from there.

Pain in the a$$ all i can say

 

[BigJase88]

Fix mine while your at it

 

[xpro]

update:

Removed the gearbox yesterday, clutch and flywheel all good. Surprisingly the flywheel was in very good shape with minimal play.

So i stripped the gearbox down fully as there was no fault with the clutch assembly. Also the release bearing was in good shape.

It took me a while to go trough all the gears and bearings, with everything looking in good shape.

Last bearing removed ( rear input shaft ball bearing) revelled some scorch marks on the outer part of it.
The bearing itself was in good shape, but the problem was that the bearing itself spun in the gearbox housing.

Under load in first gear the problem was that the complete bearing was spinning, and not only the inner part as it should. The clearances between the housing and the bearing are obviously too big.

Still looking into various options, but its looking like i will need a new casing. .

Will put some pics up later

 

[BigJase88]

Think i'll stick with the turning the music up idea

 

[xpro]

Hi,
Just a quick update and a few photos.

I finally put the gearbox back together after renewing the main shaft bearings and all the seals.
( after spending some time on the net, this appears to be a very common problem with 02M gearboxes. I got some good info on the vwvortex.com)

As the main ball bearing bearing was slightly loose, but still holding in place,( it wasn't damaged, but the weak aluminium case allowed the bearing to spin in the housing ) I had to machine the top of the case where the circlip goes as it was worn and i then fitted some shims on both sides. ( My 02M gearbox was the latest type and it did not require any shims in the factory spec, but as the housing was worn due to the bearing eating into it i had to use shims on both side to reduce the shaft play. Now its perfect.

I also used Loctite 620 bearing retainer (Apparently the strongest Loctite retainer for gaps up to 0.5mm) and i tapped two small 6mm holes on both sides and i fitted two grub screws just as a precaution.
The bearing is now 100% secure and it should not spin again. Hopefully

Some pics below.

Two screws tapped in and holding the bearing in place

Just to show the bearing itself and the worn housing where the bearing is pushed in. The shiny circle on the inside is the worn spot from the bearing outer race spinning.

This is now repaired by using .6mm shims to bring the preload back as it should be, and some loctite retainer and two grub screws sitting on the bearing case.

Worn housing, eaten by the bearing

 

[BigJase88]

Yup guess thats the state of mine too!

Can't be bothered fixing mine! Turn radio up and voila

Been doing it for the 15k i've owned it