DIY Octavia 1.8t 4X4 Gearbox and Transfer box oil change

[skud missile]

Hello Boys and Girls.

Well since i bought back my Octy 4X4 I decided to change the Gearbox, Transfer box and rear Diff oil as its at 90K and doenst quite have the smooth shift as my BAM S3.

Dont get me wrong though as i dosent crunch or grind, just not as pleasant to shift with.

So i took the time to make a little "how to" thread for any one who hasnt done this before:)

As always there is more than one way to strangle a cat so follow at your own risk.

 

Tools needed:

17mm Allan key socket

4 X axle stands, must be the same travel height....obvious but you can over look this 

3Ltrs of GL-4 Gearbox oil, you will only use 2.5Ltrs depending on how well you drain the old oil. I desided on using the OEM fluids as ive heard of aftermarkets oils causing difficult shifting during cold weather, also some manufacuters put phosfourus in their oils to provide better protection against wear ecpecaily in Hypoid gears and this can eat away at the brass syncromesh in the Gearbox and will ruin the box.

Plenty of rags

Drain bucket

Anti Seize Thread sealant

Torque wrench

Oil Pump (syringe type) C/W rubber hose

 

 

The bottle on the right is the rear Diff oil so dont be thinking thats used in this job as i was changing the rear Diff today as well but forgot to take pics.

 

First this must be done while the Gearbox is still warm from a short drive as this will help to drain the old oil as gear oil is typically thicker than engine oil.

 

Jack the car up and support with the Axle stands.

 

Back off the Fill hole plug on the Gearbox with the 17mm Allan Socket, Very important you do this first as you`ll look like a right tit if you drain your oil first and cant get the fill plug out to fill back up with oil.

 

If you dont have a 17mm Allan socket you can make one with a bolt that has a 17mm head and a couple of nuts on the end for tightening or loosening.

 

Then remove both the Gearbox and Transfer box drain, Very important you remove the Transfer drain plug as this box holds around 0.5Ltr of oil so if you miss this you will still have about 0.5Ltr of old oil in the system.

 

Give it time to drain as this is quite thick oil, So clean up your fill and drain plugs while you wait and remove all metal deposits of the magnet.

Its good practice to put the plugs back into the same holes they came from so remember where they came from. Your meant to replace them but no need imho unless you rounded the heads while removing with the 17mm.

To think that VAG say these fluids are "sealed for life" is a joke! All oil breaks down and will eventually stop providing the protection from wear.

As you can see the magnets pick up quite a bit of metal shavings and sludge so these must be cleaned to keep the magnet functioning.

The one directly above is the rear Diff magnet.

 

Once fully drained apply some Anti Seize thread sealant to the fill/drain plugs and screw back in the drain plugs and torque to 25Nm

 

Fill your pump with your oil and fill your Gearbox through the Fill hole.

Now if you dont have a pump but have a air compressor handy like me i made up a simple pump as below

Simply drill 2 holes in the top of your bottle that are slightly smaller than OD of the hose, to provide a good air tight seal.

Cut one length short, this will be your air line end and leave the other one long as you like, this will be your oil feed line and make sure the long hose goes right to the bottom of the bottle like below

When you've filled your bottle slowly pressurize the bottle and you will see the oil leave the bottle and enter your Gearbox.

Too fast and you`ll blow the lid off the bottle lol, i did this a few times till i mastered the regulation of pressure going into the bottle.

 

Once you`ve filled it or it starts to spill out before your 2.4Ltrs is in, screw the fill plug back in but not tight and then start the car and put it into gear and let the engine turn over for 2 minutes or so then back into neutral and switch off the engine and open the fill plug once more and fill the rest of whats left or untill it leaks out again.

This is very important you do this as the Gearbox and Transfer box share the same oil and by running the car in gear you fill the Transfer box from the Gearbox as there is no other means to fill it from underneath the car.

 

I might of missed a few things but this will get you through the job

 

Cheers:)

Edited 13 October, 2013 by skud missile

[benh78]

Great write up I'll be showing it to my local garage who did gearbox, diff and haldex to see if they drained the transfer box.

[skud missile]

Cheers bud but they'll just say they did lol

[Tech1e]

Is the rear diff coming?

 

would be quite useful to some techs who I have seen drain the diff out instead of the Haldex. Top up the Haldex to find its still full (no surprise there) and they pop off up the road only to find the rear diff ****s itself as its bone dry.

[skud missile]

I can knock up a quick how to at the weekend if there's interest?

Obviously there won't be any oil being drained as I've already changed it but you'll get the idea:)

[Mullac]

I just wanted to reply to this one since it's the one that comes up even when looking for a mk2 4x4 gearbox and diff oil change on Google.

There is actually a diff fill plug but it's not easy to get to on the mk2, not sure if that's different to the mk1?. I drained mine and luckily checked if it had filled the diff after running which it hadn't. I needed to undo a 5mm Allen bolt at the top back and fill the diff with a syringe where it took about 600ml.

So in short. If you've got a mk2 4x4 pre fl and you drain the diff oil, make sure you refill it. It doesn't fill from the gearbox!

Cheers

Callum

[Octabus]

Good write up, I'm also curious about the Haldex filter, Haldex oil and rear diff oil changes .. did the guide ever get done?