Transfer Case Oil darken quickly

I agree with fisho.... having been a Toyota tech in my previous life, we used to change drive line oils every 30,000kms and to be honest, the transfer oil was always the cleanest out of the engine, diff, gearbox and transfer. Dark oil is "usually" an indication of burnt oil. A smell test will confirm that, if that is in fact the case.

The type of oil you're using is the correct one...so stuffed if I know. Are there any particulates in the oil? Is the breather venting OK?

I had a quick chat to our on-site Castrol rep here at.......... where I work now. He suggested taking a sample of the used oil some where to have it analysed.

Smell is "normal" as in not that different from clean oil. Gearbox oil is clear as new. Will try to check temperature and get a sample. Cheers.

Sorry, forgot to answer the following:
- Seems to vent OK
- No particulates or shavings/fillings that I can detect. Nothing stuck to the drain plug magnet.

Cheers.

seek and ye shall find!

in his post he says GB oil is clear as!

:-)

You are right :-((

:-))

KK

Hi Vic,

When you say the thrust washers were black, do you mean they were of an unknown black material in place of copper or they had deteriorated so badly that they appear black? How long did you drive yours with the "black oil issue"? I had plan to do the clutch in a few months so it will make sense to do all at once.

Cheers,

Didier.

Hello again
My oil was dark for one or two changes so about 18 months / 2 years and getting darker.The washers were the correct copper ones but had burnt on the thrust surface,I had the car for one oil change after replacing the thrust and it was not dark then.
Vic

G'day Ross,

I tow in 5th from time to time: flat on highway at around 100km/h when the running is easy. Gearbox oil is always clear and transfer oil problem appeared well before I got the camper and started towing. I just can't remember if it always been there or not. I bought the car second hand and changed all the fluids as soon as I got it. Transfer was clear but I don't know if the previous owner had just changed it or not.... After that, the "problem" started to appear. Never found any metal shaving.

Cheers,

Didier.

Hi,

I am 100% sure that no oil is being pumped into the gearbox. No leaks, level always full. I do carry a bit of weight in the back of the troopy but I would not think it is too much.

Best of luck RR. Thanks for your input.

Having owned several 75 series troopies over the years I found they all suffered from the same or similar problems especially when constantly laden or towing.
The input gear on the gearbox output shaft/transfer input slowly flogs the splines on the shaft out putting a very fine mist/sludge of metal dust into the oil causing the blackness, eventually the metal also helps to remove the case hardening on the idler shaft and it then contributes more metal to the oil.
I never got more than 120k out of a transfer before it needed rebuilding and one of a similar vintage to yours had worn the shaft splines down to about 2mm from the original 5mm by the time it started to make a noise. A hairs breadth away from losing all drive!
Drain the oil, take the PTO cover off the side and the black tin cover off the rear of the transfer case. Hold the end of the shaft inside the tin cover with one hand and attempt to rotate the input gear (closest to the gearbox) with the other hand. If there is any rotational movement of the input gear on the shaft you have a problem. There should also be no movement sideways between the gear and shaft either.
You must have been getting some "sludge" on the magnetic drain plug surely.

Thanks Peter, I'll do as you suggest. I had the transfer case rebuilt at 100,000 and again at about 130,000, mechanic gave me a discount the second time as he couldn't believe the problem re occured so quickly.... neither could I !
Before someone jumps in I only use overdrive on flat going over 80 kms and generally sit on about 90 - 95. Apart from the transfer case I've had a terrific run out of the 75 series, 270,000 kms trouble free but past time to upgrade.
Rob.

Thanks Peter, will check for movement as suggested as well. Didier.