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]

I'd take the plug out, making sure you catch as much oil as possible, clean up 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

[Nomad]

Two months later I finally got around to check the level of transmission oil and refill if necessary.

By closer look it turned out the root cause of the leak wasn't the drain plug but the seal which sits inside the gearbox. The flange on the CV axle was crashed I assume by a ply bar when the previous owner tried to remove the axle to replace the boot (I've seen a receipt for that). And the damaged edge has cut into the seal.



Question, to replace the seal I need to pull the axle out. Do I need to remove all 3 arms attached to the wheel hub and the strut. Or is there an easier way?

[Carolyn]

Two months later I finally got around to check the level of transmission oil and refill if necessary.

By closer look it turned out the root cause of the leak wasn't the drain plug but the seal which sits inside the gearbox. The flange on the CV axle was crashed I assume by a ply bar when the previous owner tried to remove the axle to replace the boot (I've seen a receipt for that). And the damaged edge has cut into the seal.

Question, to replace the seal I need to pull the axle out. Do I need to remove all 3 arms attached to the wheel hub and the strut. Or is there an easier way?

Remove the bolt connecting the arm that goes from the chassis to the hub.  Remove the bolts at the bottom of the strut that attach it to the hub. The assembly will swing away far enough to get the axle  out of the gearbox.  I think it helps to detach the caliper from the hub too.

[boor]

As Carolyn said - have done it this way a few times.
It's ideally a 2 person job, never attempted to do it on my own.
Be careful when putting the shaft back in - that's when the seal can get damaged (don't ask how I know).
In general, these seals are quite fragile and I was getting a new one every time the shaft was out.
Cost of seal vs. the hassle to go and re-doing the whole process and you'll have to get a new seal anyway.
Do it once and right.

[Nomad]

Brilliant, thank you.

I've ordered a seal puller to make it easier too.