Slight oil leak between transfer box and autobox

[knicko]

I have noticed a slight leak at the forward end of my transfer box, where it mates with the back of the automatic gearbox. It is not enough to drop oil on the ground as I would certainly have noticed this. However, there is definitely wet oil around the join. It certainly appears to be oil and not ATF, so I presume I have an oil seal gone on the input shaft of the T Box?

I have searched the forum and see from a photo by Bob Murphy (I can't attach photos to posts yet) that the input shaft has a metal cover which appears to house an oil seal that sits over the input shaft. The metal cover is also gasket sealed and bolted to the forward face of the T box by the look of it.

I presume that the mating surfaces of the T box and Autobox are just bolted together and do not need sealing as there should be no fluids in this space?

Looking at this, I presume the fix will be to disconnect both propshafts and electrical plugs from the T box, then uncouple the T box from the autobox and remove the T box, so that I can get at the offending seal and replace it? Will I also need to lower the back end of the autobox to gain access to some of the bolts?

Once the T box is out, can I replace the seal just by removing the plate around the input shaft, or will I have to open the T box itself?

Once drained of oil (not much I know), how heavy is the T box as I will probably be tackling the job on my own with car ramps?

Are there any other things/problems that I need to consider?

Many thanks, Nick

 

[BobMurphy]

If you really, really, really want to go to the bother of doing this for a slight oil weep then OK.

As you say, there is an oil seal at the front of the Transfer box - Part No. =

36102J (90311-40021 SEAL, TYPE T OIL (FOR TRANSFER COVER).

And there is one in the back of the auto box extension housing - Part No. =

35735A (35735-30020) RING PLATETARY OUTPUT SHAFT OIL SEAL

Remove the T-box lever and Auto Box lever (just in case). Drain the oil from the Transfer Box and uncouple the propshafts and wiring (make a note of which plugs go to which of the three detector switches). Set the T-box lever to 'HL' (High, Locked).

Jack the T-Box and remove the cross Member and lower support bracket.

You may have to lower the rear of the auto box to get at the coupling bolts and to wriggle the T-Box free of the Transmission Tunnel - I did have to do that on my manual box. Use a second bottle jack to support the Auto Box. You will probably get drowned in ATF so I would drain the Auto Box before starting just in case.

Once everything is about to separate it would be best to have a transmission jack handy. The T-box is an awkward shape and won't sit on a jack without wood blocks to support it.

Alternatively, lie underneath in your heaviest boiler suit with a couple of sacks on your knees and use your knees to support the T-box as you wriggle it free - it weighs 50 Kilos so be prepared.

Once it is out - Do Not pull the two Transfer Levers forward from the front of the T-Box casing or the detent balls & springs will drop in behind the shafts and you will have some grief to sort out (its easy enough with the box on the bench, but if you don't discover it until the T-Box is re-installed it will be a pain).

You won't have to open the T-Box to change the oil seal - removing the front housing will be enough. There are a pair of sealing rings on the shaft (like piston rings) so watch out for those and treat them carefully. There isn't a gasket under the front housing - Toyota just use silicone sealant or RTV sealant or something.

When you are ready to start I'll post up some pictures to help you (it will take me a while to sort them out).

Good luck. Its not difficult - just heavy, dirty and awkward when doing it on your own. As always, don't strain anything by letting the box hang on the shaft as its separating.

Keep us posted.

Bob.

 

[knicko]

Ok Bob, thanks for the thorough briefing!

I might now have access to a hydraulic ramp and this sounds like the way to go, especially if I can recruit someone to help me with the heavy lifting/wriggling the T box free. You make a good point about just leaving the 'leak' until it becomes unacceptable and for now, I think I will do all the fluid changes (including all three diffs) that I planned and see if the leak is still minor with new centre diff oil.

Out of interest, why would I be showered in ATF while splitting the T box from the autobox - surely there is a seal on the back (output shaft) of the autobox that would prevent this?

Many thanks again Bob.

 

[BobMurphy]

Out of interest, why would I be showered in ATF while splitting the T box from the autobox - surely there is a seal on the back (output shaft) of the autobox that would prevent this?

The Transfer Box Input Shaft passes through an oil seal on the back of the Auto Box. When the Transfer Box is removed there is nothing to stop oil coming out of the auto Box - particularly if its hanging low at the back.

I haven't done this with an Auto Box, but I got covered in oil when I first removed a Transfer Box from a Manual Gearbox .

Learning Curves and all that .

Bob.

 

[knicko]

The Transfer Box Input Shaft passes through an oil seal on the back of the Auto Box. When the Transfer Box is removed there is nothing to stop oil coming out of the auto Box - particularly if its hanging low at the back.

I haven't done this with an Auto Box, but I got covered in oil when I first removed a Transfer Box from a Manual Gearbox .

Learning Curves and all that .

Bob.

Ah of course! Obvious now you mention it. Thanks Bob.