Transaxle Failure

Wow! Great job! This is the result of Prius owners stick and work together. If something happen to my Prius out of warranty, I am not afraid to fix it myself! Thanks for all the inspirations.

 

Peter, just a little advice.
On a big job like this it's a good idea after a week or so to slide under the car and recheck all the fasteners you can get to, just in case.
I'm assuming you repacked the CV joint with the right grease?

 

Just a big THANK YOU for posting the play by play of this job. Great pictures and documentation! Generous sharing of your experience adds much to the value of Priuschat as a knowledge source for all of us!!

 

Pat, you don't need to pack the CV joints. Transmission fluid leaks through the seals and fills the boots, and then dirt packs in there automatically.



Tom

 

I am buggered if I know how that can happen Tom.
Yes I saw your smilie

 

Before opening up the transaxle, you might take a peek at some of the earlier work in this area. Florian over in "Prius Technical Stuff" disassembled a NHW11 transaxle and Hobbit has also done some work in this area. Also, there is Arts Automotive, a bit late but interesting no less:

Rebuilding a Toyota Prius Transaxle -- Art's Automotive, Berkeley, CA
Replacing A First Generation Prius Transaxle
​

For my part, a couple of thoughts for the disassembly ... as you are able:

• Where does 'debris' collect? - An oil change takes out the suspended debris but stuff that settles out will ordinarily seek a lowest point. Insights about where any other areas might be located, especially the differential area, relative to the drain and fill plugs would help. NOTE: you might consider the current oil a 'flush' and change it out after say 2-5,000 miles to remove anything that might have been left over.
• What is the normal oil level relative to the moving parts and stators? - I'm pretty sure the differential is partially in the oil pool but I don't have anything that shows where that level might be relative to the differential gears. In theory, a lower level might further reduce the internal drag but cooling is also important.
• High resolution, close photography of the leaking and non-leaking seals. I would expect them to be difficult to remove and would suggest taking out the 'good seal' first before taking out the one that failed.
• Carefully check all teeth for evidence of a chip. One hypothesis is a tooth or part of the chain lost a chip, which was ground up into debris that destroyed the rest of the parts.
• Check the coolant races for any 'gelled' material. Hobbit reported finding a gelled material in an inverter coolant race. If you find anything, having a sample for analysis would be great (PM and we can work out the details.)
• The lubricant flow from the transaxle oil pump remains a mystery. Other than trying to force a colored fluid through and looking for where it seeps out, I don't know how to easily map the pump to outlets.

These are just random thoughts and if you're able to deal with any of them, good. Whatever you report will be well received.

Bob Wilson

 

Regarding the throttle body and throttle plate, this accumulation of black gunk is normal. It appears those parts have not been cleaned since your car was new.

The reason for this accumulation is the engine's use of Atkinson cycle where the intake valves remain open past BDC, so some of the fuel/air charge can move back into the intake manifold. A portion of the fuel/air charge includes previously combusted exhaust gases that remain in the combustion chamber after the exhaust valves close. The carbon deposits stick to the throttle body and throttle plate.

You can use throttle body cleaner for this purpose. I have successfully used rubbing alcohol and Q-tips to scrub off the dirt.

I'm also interested in hearing about the process you used to rebuild the axleshafts.

Its really nice to see how you completed the repair, to note that you did not need to suspend the engine from above, and to hear that you felt the job would be made simpler with access to a transmission jack.

Again, congratulations on the successful repair and we are looking forward to seeing your transaxle dissection when you get to that project.

 

I swear I wasn't in any way involved with those half dozen pat sparks'

But there is that hazy night of heavy drinking .....

Uh oh

 

After seeing these pictures, I have decided to stop driving my Prius, just to make sure I never need to replace the transaxle.

Tom

 

Peter:

Sorry to report this is a normal part of Prius operation. I finally got around to cleaning my TB last fall on my Prius, no difference in operation

With both my FJ and my Prius, cleaning the MAF is a better choice. This is the MAF in my FJ after only a year



After cleaning



The MAF guts after cleaning



Cleaning the MAF made a huge difference in how my FJ auto shifted and how it ran. Little difference in the Prius

That's weird. On my FJ, the rear axle fill plug is very easy to reach



The dribble of gear oil is because I had checked the fluid level before taking the photo

The front axle is a lot harder to get to, unless you remove the front skid plate

An entirely normal feeling. Imagine a large petrochemical plant after major upgrades, and you're the Project Manager who is responsible for the startup. My butt had never puckered so much in its sad little life

 

To really play it safe I'm going to hide in my basement

 

Clean it up, dry it off, and dip it in Cosmoline. That should do the trick.

Tom

 

Peter,

Thank you for sharing your adventure with us.
It's been educational, it's been inspirational.

/Gordon

 

Hey, it looks like, in IMG_7177.jpg, that the little blockoff plate
is on the right way without that tab sticking out toward where the
resolver harness will pass. Did it come like that, or did you
flip it?
.
Yes, this is only peripherally related, but something I noticed..
.
_H*

 

Ok, dumb question of the day...So what Peter replaced was the transaxle along with the mg1 and mg2 that are all together in the same housing? He removed the inverter from the top of this housing and removed the axle shafts from the housing. Then he disconnected the transaxle from the gas engine so it could come out the bottom of the vehicle. Am I understanding this correctly? The transaxle cooling system cools the transaxle, mg1 and mg2 right?

Thanks,
Dave

 

Yes. The inverter cooling system also cools the transaxle, and MG1 and MG2 live within the transaxle case along with the power split device and the differential gearing that drives the axleshafts.

 

Would you be kind to do a write up to check and clean the throttle body? I don't believe we have a "How To" guide yet. I am sure many are itching to check how dirty theirs are.

 

What? Do you have any idea what Cosmoline would do to soft, sensitive skin .... oh, wait a minute.



You're talking about something else. Never mind ....