I just rebuilt my transfer case, I made a thread following the process. When I was rebuilding it I also installed headers and had to chose my car on for a few moments. I thought the rear of the transmission was sealed, but it wasn't, and transmission fluid blew out of the back of the transmission.
I didn't think much of it and went ahead and emptied my transmission thinking I would do a normal drain and fill once the tcase is installed. Finished up the job and everything was good.
My transmission is the A443F trans from the 80 series. It has a 6quart drain and fill according to the FSM, 13q dry fill. It drained for about a week while I was rebuilding my case, and the front end of the vehicle was lifted.
Long story short I started with 6 quarts and it didnt touch the dipstick when warm. I expected this since im sure that I ended up draining more than 6 quarts. I ended up adding 2-3 more quarts before I could see it on the dipstick, but it wasnt even at the cold line while it was hot. It seems like everything that I added after that was not raising the level of the dipstick, it was staying low. I added a bit at a time then cycled the shifter, drove it, remeasured. At one point it started dumping fluid out of my vent tube that exits out near the middle of the dipstick tube.
To me this was an indicator that the transmission was overfilled, but it was really confusing because the dipstick was reading very low.
I did further digging today and ran into some serious issues. There are two air vents that lead to the dipstick, I wanted to see which one was leaking. Its an extremely tight area but this appears to be the setup:
Lower vent at dipstick -> attaches to middle section of transmission at the frontmost portion of it, ends there
Upper vent at dipstick -> leads to middle section of the transmission at the rearmost portion of it, attaches there to the second transmission vent, and has a Y tube that leads to two other spots. The ends of these tubes connect to the top of the transfer case, and then the actuator
Since the tube at the top of the transfer case was the easiest to access, I removed that one first. When I removed it, ATF dripped out. That was a pretty big red flag to me but I started the car. I expected transmission fluid to run up from the transmission through the vent, and come out of the disconnected hose
Instead what happened was ATF fluid (not gear oil) started spewing out of the top of the transfer case the moment the wheels started turning.
At this moment, i'm fully expecting that my transfer case is entirely full of ATF fluid mixed with gear oil.
What I'm unsure of is if the ATF ran from the vent valve back into the transfer case, or if it's somehow entering from the input shaft.
The input shaft feels really unlikely, though. The transmission output leads into the female transfer case input gear which is a solid bit of metal that petrudes from the case. There is a seal on both the transmission end and the transfer case end. Once the input shaft is on the transmissions output shaft, it cannot move forward because of a snapring and the outside of the transfer case. It is fully and properly seated, or else it would have never been able to go onto the transmission.
Even if one of those seals are damaged, there is a dry area between the transmission and transfer case. That area has a drainage channel at the bottom that was designed to indicate if either seal was leaking. No fluids have come from that channel.
Right now all I know to do is drain the transfer case, and presumable the transmission. If ATF got into the transfer case than in my mind that means gear oil made it back to the transmission. Whats weird is that it's been driving almost entirely normal
Any suggestions as to next best steps? Dump both transmission and tcase and pray it doesnt happen again? Are my vent lines configured incorrectly somehow? It seems like theres no where else for them to be
I didn't think much of it and went ahead and emptied my transmission thinking I would do a normal drain and fill once the tcase is installed. Finished up the job and everything was good.
My transmission is the A443F trans from the 80 series. It has a 6quart drain and fill according to the FSM, 13q dry fill. It drained for about a week while I was rebuilding my case, and the front end of the vehicle was lifted.
Long story short I started with 6 quarts and it didnt touch the dipstick when warm. I expected this since im sure that I ended up draining more than 6 quarts. I ended up adding 2-3 more quarts before I could see it on the dipstick, but it wasnt even at the cold line while it was hot. It seems like everything that I added after that was not raising the level of the dipstick, it was staying low. I added a bit at a time then cycled the shifter, drove it, remeasured. At one point it started dumping fluid out of my vent tube that exits out near the middle of the dipstick tube.
To me this was an indicator that the transmission was overfilled, but it was really confusing because the dipstick was reading very low.
I did further digging today and ran into some serious issues. There are two air vents that lead to the dipstick, I wanted to see which one was leaking. Its an extremely tight area but this appears to be the setup:
Lower vent at dipstick -> attaches to middle section of transmission at the frontmost portion of it, ends there
Upper vent at dipstick -> leads to middle section of the transmission at the rearmost portion of it, attaches there to the second transmission vent, and has a Y tube that leads to two other spots. The ends of these tubes connect to the top of the transfer case, and then the actuator
Since the tube at the top of the transfer case was the easiest to access, I removed that one first. When I removed it, ATF dripped out. That was a pretty big red flag to me but I started the car. I expected transmission fluid to run up from the transmission through the vent, and come out of the disconnected hose
Instead what happened was ATF fluid (not gear oil) started spewing out of the top of the transfer case the moment the wheels started turning.
At this moment, i'm fully expecting that my transfer case is entirely full of ATF fluid mixed with gear oil.
What I'm unsure of is if the ATF ran from the vent valve back into the transfer case, or if it's somehow entering from the input shaft.
The input shaft feels really unlikely, though. The transmission output leads into the female transfer case input gear which is a solid bit of metal that petrudes from the case. There is a seal on both the transmission end and the transfer case end. Once the input shaft is on the transmissions output shaft, it cannot move forward because of a snapring and the outside of the transfer case. It is fully and properly seated, or else it would have never been able to go onto the transmission.
Even if one of those seals are damaged, there is a dry area between the transmission and transfer case. That area has a drainage channel at the bottom that was designed to indicate if either seal was leaking. No fluids have come from that channel.
Right now all I know to do is drain the transfer case, and presumable the transmission. If ATF got into the transfer case than in my mind that means gear oil made it back to the transmission. Whats weird is that it's been driving almost entirely normal
Any suggestions as to next best steps? Dump both transmission and tcase and pray it doesnt happen again? Are my vent lines configured incorrectly somehow? It seems like theres no where else for them to be
