75 series leaking oil from top of gearbox????

As has been said the seal between the transfer case and gearbox can go causing the transfer case to pump oil into the gearbox leaving the transfer empty eventually.
Unfortunately this symptom is usually a sign of bigger problems with the transfer case which could ultimately lead to loss of drive to the wheels.
You don't say what vintage the 75 is but several models had problems with the main input splines wearing away which then allowed the gear to spin on the shaft which stopped the drive to the wheels.
Best to get an experienced 4wd place to have look at it before that happens as the resulting to could cost more than repairs.
I had it nearly happen twice on two troopies, the first one an 87 2H powered one and the second time an early 90's 1hz powered model. Both started pumping oil into the gearbox which instigated further investigation. Parts can be bought from Don Kyatt/Terrain Tamer for much less than genuine but the Toyota gaskets are of better quality.

As Peter says.
I have suffered catastrophic failure of the transfer case due to it pumping oil into the gearbox.
The problem starts with wear of the splines in the T/C input shaft and creating end float for the input gear. The oil passes along the splines and through the mainshaft bearing. The oil seal runs on a lip on the input drive gear, has no control over the oil passing along the splines and through the bearing.
This shortage of oil in my T/C caused collapse of the idler gear/shaft bearings (caged rollers) which combined with spline wear of the input shaft disengaged the gears sufficiently to initially chip teeth then destroy the gears.
Luckily I was still mobile and able to effect a replacement transmission without an horrendous recovery cost.
I had travelled less than 6000km. since the last oil change when all levels were correct. It may take no more than 1000km. to empty the T/C then not much more to destroy it.
mike

I forgot to add that when I checked the input shaft splines in the transfer case after noticing changing oil levels that instead of being square section about 3mm they were at best 1mm triangles, very very close to total failure.
It isn't hard to check the wear between the input shaft splines and the main drive gear, drain the oil, remove the PTO cover (big oval cover on LHS), remove the "top hat" cover at the top on the back of the transfer, then with no load on the drivetrain, holding the shaft and gear with your hands see how much movement there is between the two, there should be virtually none.

Benny,

Further to the others advice, we effected a temporary "fix" on a 75 series work ute, with some silastic, as we were busy at the time and needed the vehicle.

Cleaned up the top of the transfer case, and in doing so found a piece of gasket sticking up above the t'case. Got the case as clean as possible, using rags, solvent etc and ran a strip of silastic along the t'case join, and let it set over night.

Don't remember it being a huge success, but did decrease the loss of oil, until we received the gasket and got time to do the job. We had a service ramp as well, and ran the ute up on it each night to top the level up.

In another incident, we had an '84 HJ60 wagon fitted with one of these "transfer hoses" (available from ENZED) and it also developed a leaking rear t'case seal. Long and short was, over a 1200km round trip to Mt Isa, as the oil leaked out of the t'case, the hose was also draining the gearbox oil. Travelled home last 40 clicks with only 3rd and 4th gears. Reconditioned tranny about $3800.

There was recent thread here, maybe last month or so, that was addressing the loss of motion, with L/C vehicles/transfer cases.

Bob

Re replacement of the gasket between the t'case halves, we merely removed the rear tranny cross arm, and lowered the tranny with a bottle jack. Of course removed the rear tail shaft first. Split the case after cleaning off all accumulated dirt, insects, grass seeds and prickles. No doubt some flex in the engine mounts, and if they can't take it then need replacing anyway. The fan will foul the shroud too, but gently lowering the jack shouldn't cause any damage.

And talking of those plastic fans, I'd think that a 75 might need a new one, just to keep on top of any dramas...........the originals fans are now well over 20 years old.

Probably a good time to check for any wear as Peter detailed, and certainly tighten up the big nut on the shaft.

Having a service ramp, ours wasn't a flash hydraulic one :-), makes a difference as you can stand up to effect repairs.

Not sure how such a repair would go on a 79 series, as when I checked mine the other day, the "top hat" Peter mentioned has been replaced by an flat alloy plate, and there doesn't seem to be a great deal of clearance between rear of case and the fuel tank. Will find out if it happens, I guess?

Bob

That may have been a previous post of mine Bob
mike

BTW its probaly not comming out of any seal at the top, it will be comming out of the breather.

cheers

Yep that is pretty much what everyone else said.

Hi Bantam
Does this problem happen with the 100 series, HDJ100R 1hdfte.

Hi Bluefella

Those gearboxes are different to the one that had the seal fail, so the answer on no, however one of my 100 series did have the rubber boot that sealed the gear stick to the gearbox come adrift, I found it after a few days of getting water in the gearbox.

I thought I had a split case, but after near pulling the box out found the problem, I was able to put it back on and it sorted the problem, no more water which was good as it was doing a .8 metre water crossing twice a day.

Bantam,

Just a couple of thoughts on your post.

If one was to use the drain plugs instead of the filler plugs, using one of these hose kits, the oil would find its own level, leaving the gearbox lacking oil, and the t'case would be overfull, by quite an amount. Far better to use the filler plugs, or bite the bullet, and get a new seal fitted.

Second thought was that a drain mounted hose would be susceptible to damage from over aggressive driving in off road situations?

Bob

The dirty great cable tie I put around where the boot fixes to the gear stick on my 80 series is still in place and still stopping hot oil smells in the cab. That was 12 years ago.

as I said my experience is those equiliser hoses do nothing
why replace the oil?

just drain it to correct level from geabox and top up transfer

i had exactly as you describe with the same set up and occasionally id need to do that and as i said im not talking about much oil.

first time I did it i was disapointed as it looked like no where near enough extra oil in the gearbox to do anything
- but it fixed the issue of gearbox weeping oil for a good few months