Transaxle Fluid Change

It's not clear what you mean by "shifting the tranny into brake mode". If you are saying that you are not getting smooth braking to a stop, then it might be because your friction brakes are rusty. Get up to some moderate speed in a parking lot somewhere, put the shift into neutral and brake to a stop a few times. That forces friction braking and will clean off the rust.

In any case it is definitely time to change the ATF fluid as well, but that is preventative maintenance, not a fix.

 

OK, engine braking B mode. No, in my use it is a fairly smooth transition. If you are otherwise seeing normal operation in EV mode below 30 mph, then I would not suspect the transaxle. But without any more specific symptoms, I can't say much. How does the engine run normally: smooth idle, no misfiring?

Generally you don't need to manually select B mode, unless you are in very hilly area.

 

I've got 130,000 miles on my 2007 Prius with no problems other than the common warranty replacement issues and I can count on one hand the times I've used the engine braking. I would read the attached pages well and decide if it's useful to use it as much it appears you are. Can do some damage if you engage it at too high a speed or keep it on and accelerate to too high a speed. Transaxle fluid replacement is pretty simple and you are overdue. There are lots of posts about it. If you're a Do-it-yourself mechanic you can save a lot of money on this one.

 

I changed my ATF ahead of schedule at 80k & it is one of the best thing I ever did for my Gen2. Ever since, the hybrid system charge up the battery much more efficiently on top of smoother shifting. It was the best $40 I've ever spent on my car.

 

While I agree changing the transmission fluid in the Prius is a good idea both to help reduce gear and bearing ware and reduce the risk of possible motor/generator failure, it should be noted that the Prius never changes or "shifts" gears, this even includes reverse.
There is no reverse gear, no neutral, and there are also no brake bands or clutches. Nothing in the transmission changes apart from the direction and speed of the motor/generators, and whether they are being used as motors or generators or in the case of MG1 being allowed to spin freely.

John (Britprius)

 

If you want an accurate view of what maintenance has been done, at least by a Toyota Dealer, including maintenance, repair, warranty recall or Limited Service Campaign work register on the Toyota.com Owners Official Website. You can plug in your VIN and see the cars history.
Odds are the Transaxle fluid has never been changed. Toyota considers it "lifetime".
Luscious Garage, a very competent Hybrid Repair Facility in San Francisco area, recommends every 30,000 miles. Seeing what mine looked like at 120,000, the first time I changed it, I would say somewhere in between , maybe 60,000 is reasonable. Also depends on how hard you drive it. Even though as Britprius said there aren't the conventional gears, there is a planetary gear, ring gear, bearings, plus the heat generated by the inverter, the relatively small volume of ATF all to consider. It has its own cooling system, but the preventative maintenance will save you big bucks in the long run.

 

My understanding is the only time shifting to B is warranted is on a protracted downhill run, when there's a good possibility the hybrid battery will charge as much as possible and there still is a goodly extent of braking needed, to avoid overheating the conventional brakes (which will come into play once further hybrid battery charging is not allowed).

I'd get on a transaxle fluid change as soon as possible. There's a good change it's never been changed, so sooner the better. That said, if there's an abnormality in the transaxle, a fluid change is not necessarily going to cure it. But still, doesn't hurt, and eliminates one variable.

 

That's awesome. It proves once again that preventative maintenance pays off in better performance, mileage and fewer breakdowns. Gen II really has been the Gold Standard in hybrids as far as I'm concerned. Anything with better mileage is a compact.
As Clint Eastwood said in Dirty Harry, "A man's gotta know his limitations". But with some friends on Prius Chat, you can expand your abilities.

 

Sounds good. Only niggle: was the car level when you refilled? Likely not that much difference with slight tilt.

 

Congrads !! Sounds like you covered all the basis. A little peace of mind goes a long way doesn't it ?

 

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I checked my 2007 Prius with a level running along the bottom line of the doors. Have a 4-foot level, so can't just set in on the panel of the open door. Even when sitting on flat ground, this is not exactly level. The rear of vehicle sits higher than front. Probably close enough, you won't over or under fill the transaxle by using this as a measure. I'm sure on the lift under frame at the dealer, it is very close to this.

 

Hi guys, does anyone have pdf on how to change a transaxle fluid?

 

Yes. I'm attaching it. I think the 2005 is the same as my 2007. I believe it was the GEN I that has a removable transaxle pan. Hope the European Version is the same.
There's also a very good YouTube video of a 2004 Transaxle fluid change. Note that he removes the drain plug slowly to avoid a big mess.

 

thank you

 

Hey Austin, I am a qualified technician and recieved toyota factory training on the gen 2 prius some years ago. I now own a 2007 and a 2005 and love them. To answer your question, yes, it's a very good idea to change the trans fluid as there are moving-wearing parts to these as in any trans, however they do not have the same components as any other cvt or auto trans, with e few exceptions. Any trans can benefit from clean oil, period. As for the clunk you're describing, that is the drive plate that is sandwiched to the flywheel similar to a clutch in a manual trans setup. This is designed to act as a damper in the driveline and a safety "fuse" should a total seizure occur in the engine at highway speeds, to prevent wheel lockup and accidents. This increasing clunk as miles accumulate is a common development and it can become a little worrisome although you may rest assured, they do not fail, rather just become annoying. If you study the design of a clutch drive plate you will see springs in the center that are designed to soften the uptake or application of torque so as to lessen the initial harsh impact on the vehicle drivline components and occupants. I purchased my 2005 gen 2 with a bad injector and the po drove it for several months with a misfiring engine. As a result the driveplate is very noisy and clunky. I don't worry because I know what it is. Hope this is helpful.