Transmission Gen ll Drain and fill or Flush?

Yes, the transaxle can be drained and filled.

Neither the shop or the dealer is right. The Prius transaxle oil change is a simple drain and fill, similar to an oil change. Actually, simpler because there's no filter to change. There is no machine required.

 

Well said xl, I could not have answered it any better.

 

Isn't it a bit of a bear to DIY, due to trapped air? I do oil changes in my sleep, and I've done coolant changes on a lot of Hondas, but I've heard Prius coolant change is more difficult.

Also, I would just use the expression drain and fill, not "flush". The latter implies running a lot of water through the system, not needed, leaves mineral deposits, questionable dilution and bad for the environment.

 

Tranny is easy. No air trapped. Coolant is more difficult since air can get trapped. This thread was about tranny.


iPhone ?

 

We need to be clear about whether the discussion is about replacing 1) the transaxle ATF, or 2) the inverter/transaxle coolant.

If 1), all that is required is to drain and fill the transaxle. A flush is not necessary or useful.

If 2), then it is necessary to drain and refill the coolant and then work to get the air out of the system, which is not particularly difficult.

 

Assuming it's about the ATF:

Yeah, the Prius CVT is a whole different animal than a regular automagic transmission. It does not use fluid under pressure to do actual work, its just an oil bath for a few gears and two electric motors. No hydraulic torque converter, no radiator for the fluid.

And Toyota doesn't even officially recommend ever changing it, and many never do. So don't sweat it too much. But so many smart people here recommend it. It is a very simple project to DIY, and only about $40 in fluid.

BTW, I would drain and fill the coolant, too, both engine and inverter, if it hasn't been done yet. By coincidence, that takes about $40 in fluid, too. And Toyota does recommend that.

 

I'd be reluctant to let those guys near it, considering all the misinformation. Be sure they use Toyota ATF-WS. Refill level is set by filling with the car levelled, until it starts coming back out of the fill hole.

 

The run it through the gears bit is for the valve body which a Prius does not have.

You could go to a guy/shop that uses one of the new machines that vac out the old fluid and then pump in the new fluid but that bypasses the best part which is taking the dump bolt off and investigating the magnet end for metal and then dumping the fluid in a a large wide container and looking at that fluid in the sun which will reveal any non ferrous metal not caught by the magnet. The best part of the vac machines is it bypasses the messy dump part. After a vac you can pull the pan off an auto and its pretty dry no mess. No pan on our cars.

It is for all intents and purposes a manual trans. If you suspect the trans fluid is very very bad I would do multiple trans fluid dumps. Do my test and see. But if the trans is running great a vac machine (
car not on just suck & dump through the input hole) is a pretty good idea. Fast and possibly cheap.
Maybe cheap enough to do it again in 3000 miles.

Alot of people myself included send out there trans fluid to have it analyzed. See the trans fluid stickys at the top of the forum.

Btw, I highly recommend changing the Inverter/trans coolant also. That system is very hard on that coolant. Really very easy there's many youtubes about it. If you do get that changed as an interesting sidenote make note of the change in turbulence between the old fluid and the new fluid in the Invert coolant container. The coolant pump works much better with pure coolant. Much more aggressive pumping action. Thats a dump and fill. No vac possible.

I do my trans fluid & Inverter coolant every 30,000. I follow Luscious Garage intervals. (lusciousgarage.com)

I notice a slight increase in mpg's also when the I coolant is changed also. Car is very happy when Inverter very happy.