i have 1986 former army blazer, seems to be throwing oil out of the rear of the transfer case, have changed the rear seal twice. can't seem to see were the leak is coming from can anyone help?

 

What transfer case does it have (aluminum case is likely to be an NP208, cast iron case could be an NP203 or NP205)?

You could have a leak around the speedo output, the rear seal, around the splines inside the rear yoke, the rear output housing mating surface to the main t-case body, etc... I would clean things up really well and then determine where the oil is coming from.

Keep the t-case topped up!

 

while on the subject of transfer cases can you tell me what type of fluid to use on an 85 k10 4wd for the transfer case this is my first 4wd so i want to do everything i can to take care of it thanks....

 

Loosely related... It really comes down to what transfer case you have. The newer aluminum bodied transfer cases came factory filled with ATF. The NP205 used 80w90 gear oil when originally released, but somewhere in the mid-80's GM changed them to ATF. I can't find it now, but I have seen that using ATF is better for efficiency (mileage), but there is a significant difference in the bearing life when compared with 80w90 gear oil. The NP203 uses 10w30 or 10w40 engine oil as gear oil would kill the pump inside the transfer case.

 

if its the military blazer and its the factory case itll be a np208. if its still leaking out of the seal itself after changing, im in the same boat. ive changed mine 3 times and it still leaks. i dont know if the driveshaft is slightly pitted or what but i just basically got to live with it

 

mine is the np208 from what i read about it takes atf but i was just making sure thanks