I just changed the PSD fluid!

<div class='quotetop'>QUOTE(Floyd @ Oct 3 2006, 09:35 PM) [snapback]327658[/snapback]</div>

I'm not quite at 30K yet, but I will probably do this next spring. Is there a picture somewhere of where the drain & fill plugs are? Thanks!

 

<div class='quotetop'>QUOTE(Beryl Octet @ Oct 4 2006, 10:38 AM) [snapback]327837[/snapback]</div>

Hopefully this will help:

http://hiwaay.net/~bzwilson/prius/pri_T_cold.html

Bob Wilson

 

What fluid did you use for replacement?

 

<div class='quotetop'>QUOTE(yakky @ Oct 9 2006, 05:47 AM) [snapback]329979[/snapback]</div>

For the 04-current Prius, Type WS.

For the 01-03 Prius, Type T is the OEM and there is an Amsoil ATF equivalent. However, some of us are moving to Type WS for improved fuel economy. NOTE: we don't have wear test results for Type WS so use it at your own risk and/or setup an oil testing schedule.

Bob Wilson

 

Was the smell of the old fluid some what like melted Paraffin or candle wax? Mine was quite discolored and had a smell that was different from the new. To me it was the smell of wax?

 

<div class='quotetop'>QUOTE(hdrygas @ Oct 9 2006, 08:23 PM) [snapback]330365[/snapback]</div>

My first transaxle oil smelled of paraffin and was pretty ugly. I had it tested:

http://hiwaay.net/~bzwilson/prius/pri_T_oil.html

Soon as I get 15k miles on this batch, I'm switching to Type WS with an aggressive testing schedule. This will help us determine the service life.

Bob Wilson

 

<div class='quotetop'>QUOTE(bwilson4web @ Oct 8 2006, 11:20 PM) [snapback]329914[/snapback]</div>

Very helpful, thanks. I'd hate to have drained the inverter coolant by mistake.

 

For all you Prius veterans, can you please help define:

1) PSD
2) Transaxle
3) Differential

Are item 1) and 2) the same thing? And if 3) is actually a different item, where is it located and how would one go about changing the oil?

The 2005 Toyota maintenance schedule talks about changing the "Automatic transmission fluid" and "Differential oil" at 60000 miles on the page marked 11 in this PDF file:

http://smg.toyotapartsandservice.com/pdfs/..._service_05.pdf

Why are they separate items?

To make matters even more confusing, on priuschat people also refer to "CVT", "ECVT" and "Transmission" that the manuals don't talk about. I'm assuming that these are also synonymous with "PSD" and "Transaxle".

Based on the following thread, it seems like the Differential and PSD are part of the same unit in Priuses up to 2003:
http://priuschat.com/index.php?showtopic=1...tial&st=100

For a 2003, some recommend dropping the pan at the bottom of the engine. However, the 2004+ models don't have the pan - yet some readers still talk about having to drop the pan in order to change the fluid even with the newer engine!

BTW, I know what the transmission is like in a normal car and I've done ATF changes before, so that's not the hard part for me. There just seems to be more terminology for the Prius and inconsistencies between the maintenance manuals and confusion between the 2003- and 2004+ models.

:blink:

 

For me, all the terms that appear to refer to the transmission are synonyms. There is just one lubricating fluid (supplied as T IV or WS, depending on model year) and there is just one coolant (LLC or SLLC), depending on model year).

Seems to me that the fluid changing guidance in the 'passport' cited above is copied from another vehicle/drivetrain technology (which would explain the separate differential and the reference to towing). It does not do much to inform us how long the Prius transmission fluid *really* lasts, under what driving circumstances, how we might know if it has lost effectiveness, and what damage it could possibly do after. Those matters are currently being worked out in this internet group (and others), before our very eyes.

Anybody with a Prius can contribute to this growing understanding. Once again, I wish that Toyota was doing a better job in advising us how to maintain Prius transmissions...hybrid synergy drives...spinning thingies.

 

<div class='quotetop'>QUOTE(tochatihu @ Oct 19 2006, 09:17 AM) [snapback]335010[/snapback]</div>

Ah, but if you read the very first page of the PDF file, you'll see that it IS referring to the Prius! Perhaps the file is for the Japanese/Canadian/Euro Prius instead of the US version, but it seems to me that the Differential and ATF fluids are different things.

Well, when I actually get closer to the time of changing those fluids I'll crack open the service manual PDFs I downloaded from Toyotoa techinfo. I was just hoping that someone else on this board might have already found the difference between Differential and ATF for the Prius. For the time being I'll assume that they are the same thing, but I'm not 100% convinced.

 

<div class='quotetop'>QUOTE(Ari @ Oct 18 2006, 01:56 PM) [snapback]334676[/snapback]</div>

PSD - Power Split Device is a planetary gear that connects the engine shaft output to the planetary gear carrier and spider gears. This carrier also has a tang that turns the transaxle oil pump. The sun gear is driven by MG1, sometimes called 'generator' and via computer control, provides the variable part of continously variable transmission. The outer ring gear connects to the rest of the fixed ratio gears and MG2, sometimes called the 'motor.'

transaxle - the assembly to the right of the engine when facting the engine compartment, just under the power inverter. This assembly includes the PSD, MG1, MG2, fixed gears and differential gear.

differential - the final gears in the fixed gear set that provides power to the front wheels. The wheel shafts connect to the differential output shafts.

All moving parts are lubricated and cooled by the transaxle fluid, which comes in two types. Type T-IV is used in the 01-03 Prius and Type WS is used in the 04-current Prius. Some members are investigating used of of Type WS in the 01-03 Prius. There is no separate lubrication system for the differential gears.

Bob Wilson

 

Confused.

Bob says PSD, transaxle and differential are all the same. One fluid change for transaxle takes care of all three. But in his like showing a fluid change he talks about the inverter and that he accidently drained that and so changed the fluid for the inverter and transaxle. So I am at 55k and want to change the fluid people worry about at 60k. I have a 2005. Is it the transaxle or inverter to worry about?

Thanks for any help.

 

<div class='quotetop'>QUOTE(etyler88 @ Oct 26 2007, 10:54 AM) [snapback]530699[/snapback]</div>

The power-split device (PSD) is composed of a set of planetary gears and a shaft. Those, and some differential gears, reside in the transaxle, along with some bearings, washers, a chain, two motors, an oil pump, and a few sensors.

The transaxle is lubricated and cooled by transaxle fluid, which can be drained via a drain plug on the underside of the transaxle.

The transaxle motors are also cooled by coolant fluid. The transaxle shares a coolant circuit with the inverter above it: coolant from the inverter radiator passes through the inverter, then to the inverter pump, then to motor-generator 1, then to motor-generator 2, then back to the radiator.

That circuit can also be drained via a drain plug on the bottom of the transaxle.

The two drain plugs are very easy to tell apart, if one has read the service information. If not:

The coolant fluid circuit drain plug is the one on the underside of the transaxle that is closest to the engine. The drain plug is a 24mm (15/16") hex.

The transaxle fluid drain plug is the one on the underside of the transaxle that is farther from the engine. On the Gen I, the drain plug is also a 24mm (15/16") hex-head fastener in the middle of a stamped steel oil pan. On the Gen II, the drain plug is a 10mm Allen fastener. No pan.

 

<div class='quotetop'>QUOTE(jk450 @ Oct 27 2007, 02:28 AM) [snapback]531084[/snapback]</div>

Thank you, that is easy to understand.


Couple follow up questions, it the lubricant fluid fill plug easily accessible on a Gen II?


Just curious what kind of substance the coolant is, is the coolant the same kind of liquid as the engine coolant fluid?

 

<div class='quotetop'>QUOTE(etyler88 @ Oct 29 2007, 09:29 AM) [snapback]531914[/snapback]</div>

Easy enough to get to, if you have the car raised up. You have to snake the fill hose in from above, but it's not too hard.

The inverter coolant is water-based, and is exactly the same as the engine coolant. It's a non−silicate, non−amine, non−borate ethylene−glycol coolant with hybrid organic acids (i.e., a combination of low phosphates and organic acids). The transaxle fluid, is, of course, oil. When new, the fluids are remarkably similar in color and feel.