I have a heavily used Sienna. It has more than 250k miles. It starts and runs and gets me around. I don't know much about it.
It has a differential with a separate fill and drain bolt. I had to guess that the differential fluid compartment existed based on my experience with an old Corolla I once had.
When I fill the differential the fluid seems to eventually seep into the transmission. It doesn't take long, probably within 10 or 20 miles.
This gets a bit weird because it causes the transaxle to be very overfilled or the differential to be very underfilled.
I'm assuming that there is supposed to be a seal between the transaxle and the differential that keeps the fluid in the two to stay separate.
This is just an assumption. I don't know much about cars.
I don't have a lot of money to throw at the van right now and if I did I would likely buy something with better fuel economy.
In the meantime I'm curious if there is anything that I should do.
Is it better for me to run with too little fluid in the differential or is it better to run with too much fluid in the transaxle? Is there a happy medium?
I know this is a goofy question to be asking but I'll take all the help I can get.
Thanks for reading!
It should be an Aisin A541E, and as far as I know they share fluid. The have separate drain plugs, but the fill from one place.
https://www.youtube.com/watch?v=on4WXjguIQg
Thanks! I've heard varying ideas so far. I haven't confirmed yet if it is an Aisin A541E but that seems to be the consensus online.
For what it's worth, there is a fill port on the top of the differential, it can be accessed by removing the air box on my Sienna.
I can't recall where I first found the fluid capacity for the differential in print. The Toyota dealership that I called corroborated the volume: 3 liters.
When I put 3 liters in the differential the level for the transaxle seems to increase. This would make perfect sense if it is indeed designed to share fluid. What doesn't make sense is the expected volume of transaxle fluid plus differential fluid giving me a reading on the dipstick which is extremely high.
I'm still rather confused about the issue but I very much appreciate your response!
Thank you!
don't forget it takes time for the fluid to migrate from one housing to the other.
Thanks again for the information. Taking your advice got me to the correct level of fluid. I previously thought that it was just an old and worn-out transaxle. I do know that it spent a lot of time as someone's business vehicle and towed a small trailer of equipment to jobsites. My guess was that the transaxle was worn out enough that I should have left the old fluid in there and left it alone.
Thanks so much for taking the time to answer my question. You saved me a lot of hassle. You might be surprised at how many times I checked that fluid and added or subtracted some, constantly baffled by the fluctuations.
The transaxle was shifting okay even when I had it way overfilled, but now it's shifting great.
When I have the time, (hopefully soon) I'm going to ask a heap of other silly questions on this forum. This has been immensely helpful so far!
Glad I could help. Look forward to your other questions.
