Changing G/Box oil HDi 90

[Blubayou]

Hi guys,

Just doing 72'000 service on the car, thought changing the gearbox oil would be a good idea for longevity.

Couple of problems, I've found what I assume to be the drain plug (a little 13mm bolt with a sealing washer) but it's not right at the bottom so any nasty stuff will be left behind. I also can't find the filler plug.

After searching the forum it seems I need to jack the back up to drain it all then refill with the correct amount through the reverse light switch as the filler plug is inaccessible.

Any guidelines? I'm afraid I don't know the gearbox type.

Thanks in advance.

[no2lurch]

the only advise i can give is make sure the plug where you fill the box back from can be removed BEFORE you drain the existing oil! you dont want to find the filler plug cant be removed leaving you with an empty box!

[jasper5]

The gearbox oil drain plug has an 8mm square hole in it and is located at the bottom of the gearbox/diff casing.

Yes, you fill the gearbox from the reverse light switch....2 litres of oil if I remember.

[Blubayou]

Thanks guys.

See what you mean now, the drain plug sits right at the bottom under the diff? What I thought was the drain plug is probably the filler and is easilly accessible from the front right underneath. I'll find out in a minute.....

[Blubayou]

Ok it's raining, so looks like it's gonna be done another day.

Major offput is the fact that I need to put 2ltrs of gear oil thro' an 8mm hole...... I remember doing this on an Alfasud many years ago with a pumpy oil can. Nearly killed me.

Any ideas? High pressure easibleed kind of thing?

[no2lurch]

from past experience, gear box oil bottles have a sort of funnel neck whihc can be inserted in the plug hole, then either turn upside down or squeeze it in.

[Blubayou]

That's what I thought but the end of my bottle is 10mm ish, this it a tight little hole....

[Blubayou]

I'm suspicious that this small bolt is not the filler as when it comes loose it feels like it's locating something!

[lozz]

box01.jpg

thats the drain plug

u have to fill from reverse light switch as above alteady mentioned By jasper,

[jasper5]

I'm suspicious that this small bolt is not the filler as when it comes loose it feels like it's locating something!

DON'T take that 13mm bolt out

[steve_earwig]

I thought the BEs had a reversing light switch just like the MLs

[Blubayou]

Laugh! Thanks Jasper5, it didn't feel right, I guess it is supporting something!

I've found what looks like the reversing light switch located on the top, if I take out the airbox I should be able to remove it & easily pour in 2ltrs of oil.

Just found a breather too, may be easier.

Best plan?

[steve_earwig]

The breather will head off inside too, so use it if it's bit enough (the one on my ML5C's is hooge and probably designed for the job as there's no filler/level plug - and didn't I have a laugh finding that out )

[jasper5]

The breather will head off inside too, so use it if it's bit enough (the one on my ML5C's is hooge and probably designed for the job as there's no filler/level plug - and didn't I have a laugh finding that out )

Thinking about it, the breather might be a better filler hole

[jasper5]

Laugh! Thanks Jasper5, it didn't feel right, I guess it is supporting something!?

It probably holds up one of the selector rods.

In the old days, VW put a bolt on the front of the gearbox casing which looked like the filler plug....it was actually the bolt holding the selector rods in position.....you had to remove the gearbox and strip to repair them.

VW later changed the filler to a large hexagon nut and replaced the selector holding bolt with a large phillips screw.