Evaluating wear material in NHW11 trans pan at 125k

Hi Chap,

Since you said that the old fluid was pinkish red and not near-black, my guess is that the factory-fill fluid had been changed by the prior owner. However it sounds like the pan had not been removed since the layer of the ferrous muck sounds much deeper than I recall when I removed the pan on my 2001 at ~60K miles.

Is it possible that the non-magnetic debris is plastic insulation from the wiring? If in fact that debris is from the bearings, and you don't hear unusual noise when the car is underway, then no worries. I would say that your transaxle wear sounds normal pending identification of the non-magnetic debris.

 

If that had been the original fluid, it would have been black, to say the least. I also second it has been changed at least once before, but the pan had not been removed

I'm wondering how much muck will accumulate in the +2004 Prius, as there is no easy way to take apart the cvt. Just a drain plug and a fill plug, no pan.

 

I changed my 07 at 6K miles. I wanted to get some better quality fluid in there. The magnet had about 1/16 of an inch film on it and the fluid smelled real good. I'm in the process of getting a PDA on it to add to Bob's fluid analysis study. I replaced it with the product linked below and the car runs perfect. I can't hear the drivetrain anymore at 90+mph.


Red Line Oil: Gear Lubricants

http://www.redlineoil.com/pdf/3.pdf

 

Hi Ed,

That was a brave thing to do - being among the first to use a fluid other than Toyota ATF WS...

What drivetrain noise did you previously hear at 90 mph?

 

You are using "Synthetic D6 AFT", the Type WS substitute, right?

Did you pull a sample of the virgin oil for a baseline analysis? This gives you an idea of the relative amounts of additives already in the oil so combined with the analysis from the previous fill, you tell what percentage was replaced. We've found that in the NHW11 Prius, about 15-20% of the last oil does not drain even if the pan is removed. I like to use the ratio of viscosity, a bulk oil property.

By all means, when you get a month or 5,000 miles, draw a small sample from the filler plug for an analysis. You want to make sure there are no chemical changes going on that might 'raise a flag.' You are probably going to be OK but I aborted my AMSOIL ATF test when the Cu levels starting climbing faster than I thought reasonable. I used the 5,000 mile sample to determine how things were working and calculate the residual oil.

BTW, thanks!!! It is good to meet a fellow experimenter.

Bob Wilson

 

Hi Chap,

I'm not sure what your unidentified debris is.

For fun, I've provided a link to 34 photos taken of a disassembled Classic transaxle. Florian Steiper, the photographer, is an active member of Yahoo Prius Technical Stuff group, took apart the failed transaxle from his 2001, and shared these photos with group members early last year.
Prius Transaxle - a set on Flickr

Note that the drain pan magnet looks like it had a bad hair day. Hope that your magnet did not look like that. If it just looks like a swollen garden slug, that is OK.

 

There are plenty of pix of the MG windings kicking around the
net, including in the Argonne/Oakridge papers. Standard magnet
wire enamel, from what anyone can tell...
.
_H*

 

I have seen similar debris in my pan and photos from the Jesse change that Hobbit documented. I am speculating that these are fragments of the case sealant that have broken off and migrated to the bottom of the transaxle. I think as it ages it becomes more brittle and begins to lose the pinkish-red color. However, I've not had much luck getting a good assay of the material.

Bob Wilson

 

If you can figure out a good way to resolve this, I sure would be appreciative.

Once the problem starts, the initial short, nothing stops it. The wire loop couples with any rotor motion to pull power into the loop. It continues to heat the adjacent wires and the problem gets worse. There is a characteristics 'rumble' at the rotor rpm but by this time, it is too late. Error codes will report MG2 too hot but that is a direct effect of a magnetic coupled short.

Florian has speculated a latent manufacturing defect. We've seen a number of failures including one that involved the replacement transaxle from a salvage also failing. My interest in transaxle oil is in part wondering if our transaxles have more in common with power transformers than we ordinarily think. Power transformer oil has unique requirements that include working in high temperatures and high voltage fields. Yet the differential gears run semi-submerged in the oil, which should promote foaming and micro-dieseling. Some of the older oil samples suggest this is going on, converting the 'transformer oil' into something else.

This remains an interesting puzzle, even more so now that the NHW20 runs at twice the voltage of the original NHW11.

Bob Wilson

 

Hi Chap,

If you have an ohmmeter, how about cleaning one of your larger pieces of non-ferrous debris, dry it, then see what the resistance is. If high, then it might be sealant. If low, then it is probably metallic.

Florian said that the bearings did not appear to be worn, so your theory that the rotor was scraping is plausible.

 

I was meaning that the entire drive train seems quieter to me since the change to synthetic D6.

 

Could someone point me to the procedure for changing the transaxle fluid on a 2003 NHW11 and what fluid the dealer and others might recommend (Toyota type or Synthetic D6?).

When I asked the dealer ~75K miles about trans fluid change they said you don't/can't do that but I am now discovering they were wrong. The car now has 120K miles and I want to change the fluid and if it is tested and safe would like to use the best fluid available or at least the same fluid that Toyota used.

Thx!

 

Yes you are way way overdue.

Its really easy. Uses Type T-IV fluid. Basically Dexron D4. Redline Oil makes an excellent D4 fluid.
Or just dealer for fluid & while getting fluid get a new pan gasket too at the dealer. Gen 1 is 4.9 quarts.
Just jack the car up in front. On jackstands.
Remove the cvt side fill bolt first (to make sure you can get it out) and then drop the pan.
Clean pan & magnet real good. Inspect closely with flashlight for any issues.
Get a funnel with long extension and snake it through from the top of the engine. Install that funnel into the fill hole. Gen I is 4.9 quarts.
Also Gen I uses mechanical shift cable linkage so spray some lubricant on that assy & cable to.
There's hundreds of detailed posts about it just search and read them all and you can get a very good feel for it. Its easy.

And your way way overdue for Inverter Coolant change too. Since your under the car I would do that to. That's really important and really affects mileage too. Again lost of posts to read to get complete understanding of that buts that's really easy too.

Good Luck!

 

Is WS really the right fluid for a NHW11? http://priuschat.com/forums/generat...mk1-nhw10-making-funny-sound.html#post1142125 mentions "Toyota ATF T-IV". Bob did a bunch of experiments like at http://priuschat.com/forums/generation-1-prius-discussion/70560-nhw11-type-ws-27k-miles.html.

 

No. Five US quarts of ATF T-IV is the correct fluid for NHW11.