Mario Laliberte

Hi guys,
I have a problem with the gearbox oil of my BJ42 1981, when driving it seem that the oil is migrating from the transfer case to the transmssion. Assuming starting from cold with both, transmission and transfer full of oil, and driving for an hour then i stopping and checking the oil, I will find that the oil in the transfer case is lower and the oil in the transmission is over flowing from the filling plug., Only explanation is that the oil is going from the transfer case to the transmission. Any of you ever had or know about this problem and how to solve it I would appreciate your input
thanks
Mario

toyoda addict

I'm not familiar with the BJ42 but on a Toyota pickup, a worn transmission output seal will cause the transmission/Tcase oil to mix.

PickleRick81

Old thread but worth an answer. There is a seal between the transmission and transfer case on h42 fj60/40 split and I believe even the old solid 3 speed cases on land cruiser fj40.

Your bj may be a h55 but it's near identical to the later h42 so it still applies.


It's been a long time since I've pulled either and it's not difficult. But, if you don't want to tackle a job that big by yourself there is a hack.

The transmission and transfer case have fill plugs. Remove each plug and drill/tap them to accept an npt to 3/8 barbed brass fitting.

Then run a high temp 3/8 oil compatible hose from the transfer case fill plug to the transmission fill plug.

Now as the transfercase over fills it pumps back into the transmission. You can run like this indefinitely. Even after rebuilding mine I kept it like this as a safety measure. Once you run one dry you can do so much damage that it's not worth rebuilding.