Gearbox oil leak

[Nomad]

Hi all,

I've replaced the gearbox oil in April this year. Redline mt90 and new Toyota crash washers 9043018008. Torqued off to spec 39Nm.
Checked a few weeks later for leaks, it was all good so I refitted the under trays. A month or so ago I started noticing gearbox oil smell inside the car. Finally had a look today and found the oil was leaking from the drain plug. I torqued it off to ~45Nm to crash the washer a bit more.

 I'm now confused what I did wrong for it to fail?

Had to order another bottle of redline as I can't tell how much oil I've lost

[Joesson]

@Nomad
I can't comment about the torque value you used, nor the use of a crush washer on an oil drain hole.
I did use crush washers ( as@ Carolyn 's suggestion ) when I refurbed the front brake calipers on my 2 as the standard flat washers did not seal.
What I am aware of is the flat washer on the sump drain plug does tend to stick in place and I have read that putting a second washer on top of the old does not provide a seal.
Did you inadvertently leave the old washer on the gear box drain hole? 

[Carolyn]

Id take the plig out, making sure you catch as much oil as possible, clean uo the seat (sealing surfaces) and, perhaps use a dowty washer.  I'm sure you can find the right size in an internet search.

Otherwise a freshly annealed copper washer should do the trick.

[Ardent]

Every day is a school day.

And today's lesson for me is, dowty washers.

[Nomad]

@Nomad
I can't comment about the torque value you used, nor the use of a crush washer on an oil drain hole.
I did use crush washers ( as@ Carolyn 's suggestion ) when I refurbed the front brake calipers on my 2 as the standard flat washers did not seal.
What I am aware of is the flat washer on the sump drain plug does tend to stick in place and I have read that putting a second washer on top of the old does not provide a seal.
Did you inadvertently leave the old washer on the gear box drain hole? 

Definitely removed the original washers, I've got them laying around in the garage

Id take the plig out, making sure you catch as much oil as possible, clean uo the seat (sealing surfaces) and, perhaps use a dowty washer.  I'm sure you can find the right size in an internet search.

Otherwise a freshly annealed copper washer should do the trick.

I've never used them before, will give it a go. The car has to go on the axle stands anyway for a gearbox oil refill.

The torque values for 1zz-fe engine gearboxes are important as I've heard from people on Avensis forum it's not uncommon to micro crack the gearbox around the draining plug thread.

 

[Nomad]

The size of the Toyota original crash washer:
outer diameter = 24.3mm
inner diameter = 18mm
t = 2mm