Changing the PSD fluid?

Some Prius drivers including me have had this fluid changed, but I only know of examples with the classic Prius. In my case I did it at about 60k miles. I asked for a new pan gasket as well, so they could wipe out the metal pan and look for chunks. There were no chunks.

Bob Wilson had his fluid changed, got a sample analyzed, and found silica in it that caused him some concern. He has modified the air vent on his, thinking that there might mave been dirt entry.

As there have been something like 10 transmission failures reported on all the groups, it is a valid concern I guess. I am not prepared to recommend that everybody gets this done, but if you are willing to DIY your own engine and cabin air filters, the savings would cover an occasional PSD fluid change. Just a thought.

 

<div class='quotetop'>QUOTE(hdrygas @ Apr 26 2006, 09:05 PM) [snapback]245941[/snapback]</div>

The oil starts out darker on the type t than dextron3, and the type ws is darker than the type t. WS is a dark blood red when new but I have started to notice on some of our customer cars it seems to actually be burning. 6 years of working on them and I did my first major repair 2 weeks ago....transaxle overheat code, mg 1 at 350*. Mileage was 120k I think, and an 02. Cust found an 02 inverter and transaxle assy for 3k at a boneyard.....low miles 15k crashjob. Customer did not want cores back. I now have a working core inverter and a not so well working core trans. I'm going to tear down the trans for my own curiosity and then donate it to a local tech school. The inverter is up for grabs. I had another 05 with 20k on it that got smacked real hard on the left front. The body shop wanted eng, trans, and HVbatt removed. The MG oil was nasty. Another customer in an 04 with 30 k on it came up 2 weeks ago from portland and he requested changing the MG oil. it was burnt. The stuff is supposed to be "lifetime" oil, but it apears to be measured in octopus years (they live 3 years). It's cheap and easy to drin and fill, I think the oil is expensive, but labor is cheap. From all I have seen in the last couple months I am starting to recomend a drain and fill every 30k as cheap preventative maint.
Regards, Mike

 

Thanks for that very informative post, Mike. I am going to recommend to Bob Wilson that he discuss Prius transmission fluid issues with you.

I may not mentioned it around here before, but I use the Graham Davies miniscanner in my 2001 Prius to monitor various parameters while driving. One that has caught my attention on a few ocassions is that the MG1 temperature will increase to values as high as 105 oC under extended heavy load at high ambient temperatures. MG2 does not get so high, and neither to any of the inverter or inverter coolant emperature measuring points. From these I conclude that the inverter coolant system is sized correctly for its job, but that under extreme conditions MG1 is not able to transfer its heat to the coolant effectively.

So far there is very little confirmation of elevated MG1 temperatures in other Prius of either model. Thus the possibility remains that mine in particular behaves in an atypical way. Will continue to monitor this issue, and start a discussion on it if more data appears.

 

Hi Mike,

Doug suggested this thread and it looks like we're in the same pea patch:
<div class='quotetop'>QUOTE(IFixEm @ May 1 2006, 01:28 PM) [snapback]248058[/snapback]</div>

When I drained my NHW11 transaxle, I noticed it smelled of parafin . . . burnt. The test results were eye opening.

My car came from west Texas and I suspect heat stress cooked the oil but it also tested with a bunch of silicon. The only source I could see was the transaxle breather plug. When I disected the breather plug, I found it was a one-way valve and as I unscrewed it, I could hear the air hiss in. So I made a modification that keeps the transaxle at normal pressure behind the air cleaner.

I'll be sending another sample for testing but noticed that after 5,000 miles, even the Amsoil was darker than expected. At least it still smelled like transaxle oil and not parafin. I just regret I didn't drop the pan on the first change and wipe everything I could reach down. I found a fine layer of "black stuff" on every horizontal surface. I wasn't prepared to clean out the little gallery that still had a cup of oil but next time . . .

<div class='quotetop'>QUOTE(IFixEm @ May 1 2006, 01:28 PM) [snapback]248058[/snapback]</div>

When you do, could you check out a couple of things for me?

1. Transaxle oil pump flows for after market cooler and filter? I noticed a couple of 'plugs' on the bottom of the outside case that suggests these may be blocking some ducting. I would really like to know if these plugs were removed, could pipes be connected to a filter and radiator?

2. Wet or dry area by transaxle breather plug? High on the transaxle, I am curious if this area really gets much transaxle oil. One of the ideas I had was to pour transaxle oil in via this port to help wash out anything that might have accumulated. But I don't know enough about the transaxle oil flow paths to know.

<div class='quotetop'>QUOTE(IFixEm @ May 1 2006, 01:28 PM) [snapback]248058[/snapback]</div>

I think the number is between 53,000 and 5,000 miles. I intend to get a year on this oil and change it again next spring. But this time, I'll have temperature data. One thing for sure, the oil get hotter after the car is parked.

I am concerned about the potential for latent heat cooking the oil . . . like in turbochargers. In some turbochargers, they have a small pump to continue circulating oil so the heat won't carbonize the oil and freeze the bearings. Speculation but I'm wondering if a pump like this might make sense. While you're in there, is there any way the oil pump cover could be replaced without removing the transaxle from the vehicle (or cutting a hole?)

When you get a chance, look for "ORNL/TM-2005/33" or "REPORT ON TOYOTA PRIUS MOTOR THERMAL MANAGEMENT". This report is looking at the heat management and concluded the bulk of it is via the transaxle oil. Worse, they indicated the existing cooling mechanisms may not be adequate. This is another reason why I'll be looking at the transaxle oil temperatures.

Well that is all for now. Hope it helps.

Bob Wilson

 

Do any of the repair manual sections have *good* sectional views
of the HSD and transaxle case, such that one could really determine
the flow paths of the fluid? The pseudo-sections in the NCF are
rather unclear about what's open to what in there.
.
_H*

 

<div class='quotetop'>QUOTE(hobbit @ May 1 2006, 11:48 PM) [snapback]248397[/snapback]</div>

I'm not terribly happy with the maintenance manual sketchs. Too often I'll take a part out and find all sorts of details not in the manual. I'm taking photos of everything (except when covered with oil.)

Bob Wilson

 

Bill, the quick answer is yes, there is a way to add a cooler/more capacity. I tore the unit down yesterday and found several interesting things. MG windings were cooked on two of about 50 winding sets. Worlds biggest cow magnet....a drum about 7" diam, and about 10" tall. I thought I would need a cherry picker to get it out of the bore. It looks like clasics and next gen can utilize a cooler. I'll get some pics and try to post them. I'm going to be at the alt fuel fair with one of the company prius. I'll have the unit in the back for those that want to see the bowels of a PSD. Henry, I keep hammering on the kids, but good help is hard to find at $10./hour. I think I have finally broke their habbit of dropping tires down to 32! Baby steps. Got to go...more to follow. Bill I'm going to put together a "kit" of parts and try to find a local cust. to donate a car for a prototype.
Regards, Mike

 

Mike, if you are within 500 miles of Carson City NV and want to install a transmission fluid cooler (or something similar) into a classic Prius, mine could be that car.

Just understand my perspective on the situation: it appears that MG1 cannot offload its heat completely, when the going gets rough. MG2 seems to do this better. I have no data on transmission fluid temperatures in particular.

 

It would be nice to come up with an 'alternate schedule' for changing all the relevant fluids. Maybe the techs here can get their heads together as they see how things age and make something that could be stickied.

 

Hi Mike,
<div class='quotetop'>QUOTE(IFixEm @ May 3 2006, 03:58 PM) [snapback]249275[/snapback]</div>

I'm also interested in the kit especially if it can be installed without removing the engine/transaxle assembly from the engine. BTW, I'm starting to get some initial results with my transaxle drain-plug mounted thermister.

It looks like the temperature in light duty commuting runs about 40 (F) higher than ambient. So 60 (F) outside -> 100 (F) transaxle oil temperature, at 80 (F) -> ~120 (F). A modest hill climb, 600 ft. ~51 mph, causes about a 5 (F) increase in temperature. A modest hill descent, 600 ft. enter 65 mph and exit 50 mph using just "B", increases the oil temperature by about 4-5 (F). I have plans for more rigorous testing.

I don't have the exact temperature profile but it looks like the transaxle oil temperature increases about 2-3 (F) about 10 minutes after parking . . . BUT these are ad hoc observations!! I intend to get better data this weekend including some high speed cruse and larger hill climbing and descending tests.

Are you a west coaster? Where is your shop?

BTW, let me know who this "Bill" character is. He sounds like one of us. <grins>

Bob Wilson

 

<div class='quotetop'>QUOTE(bwilson4web @ May 3 2006, 08:05 PM) [snapback]249408[/snapback]</div>

This worries me because I pull a trailer. I think I need to look into changing the oil on somekind of regular bases.

Thanks!

Keep up the good work and keep us informed.

 

After reading a few posts of early PSD failures - I think most of them were bogus though - I changed my PSD fluid at around 12,000 km with the factory recommended Toyota fluid. It cost me around $35 as I did it myself. The Canadian maintenance menu actually recommends a PSD fluid change, but much later at around 90,000km.

Hint: Take off the plastic dam underneath, that makes it MUCH easier!

The new fluid appears to me about the same color as Dex III. The fluid I drained was VERY dark, almost a cherry color. The drain plug magnet was also loaded with tiny slivers and fuzzies too.

I'm approaching 55,000km and will sometime this summer change the fluid again. When you consider how cheap the fluid is in contrast to a new PSD/transaxle, change the fluid.

I've also done early fluid changes in my new vehicles with rear axles, and was surprised at how much crap ends up on the magnet after only 1,000km.

 

Can that stuff be disposed of in an environmentally sound fashion,
i.e. like recyling used oil?
.
_H*

 

<div class='quotetop'>QUOTE(hobbit @ May 4 2006, 08:58 PM) [snapback]250007[/snapback]</div>

Yes. It is just a heavy duty oil. Take it to your favorite recyclers and IMHO send a sample to an oil testing service. Only by mapping the actual oil characteristics do we have a chance of figuring out sensible service intervals.

BTW, I ran the Amsoil ATF for 7,000 miles: installed at 53,000 and flushed at 60,000 miles. The weekend before the oil flush, I installed my transaxle vent modification to address the high silicon load found in the original oil. This modification is under test and shown here for informational purposes:
<blockquote>http://hiwaay.net/~bzwilson/prius/pri_vent.html</blockquote>
Bob Wilson

 

I don't think Prius PSD's are going to drop like flies any time soon. I thought I should check that repair order mileage, and 120k was wrong it was an 01 with 159k. We have about 475 vin numbers (1st and 2nd gens) in our customer files. Several have more miles than that one and no failures yet. The autopsy report will find this unit failed as a result of an electrical failure that would not be atributed to lack of lubrication. If what happened is what I think happened, then additioinal thermal transfer would not have helped either. I won't go into specifics.
That being said, I do have a few ideas to improve capacity, aid in heat exchange, and reduce deposits. I also like the idea of finaly, after doing this for decades, being able to look a custmoer in the eye and tell them to change their alternator oil. I have one of the fittings I need, a second to scrounge up tomorow, and then a small cooler and a simple mounting kit/method. There is a good possibility I will have a demo prototype at the alt fuel fair in Lacey Wa. on 5/6/06 I have waisted more time the past few days looking at both gen PSD's, the oil pumps, and brass fittings than I care to say.
The best part for you is it will be a simple DIY instalation, or an inexpensive labor charge. There is a couple details that if you miss at best you scrap a $110 part, at worst.....the whole PSD. I think I can build them on an exchange part basis unless there is a huge demand. Then I'll invest a couple hundred dollars and stock a few from our parts department. It will be at least a month before my wife got the credit card bill. If we do it on an exchange basis, nobody has to buy the $110 part. I modify yours and sell it to the next person with a cooler and hardware. A couple bucks for a little time and I think we can do the whole thing for not much over a hundred dollars. I have to get some cooler prices for an odd piping size.
More to come...Regards, Mike

 

<div class='quotetop'>QUOTE(IFixEm @ May 5 2006, 02:34 AM) [snapback]250130[/snapback]</div>

Please add one 2001 Prius to the waiting list, Mike! I wish to keep the fluids happy. The motor windings' insulation will just have to look after itself (;>)

BTW if you have any crapped-out NHW11 accelerator pedals in your shop I can renovate them also on an exchange basis. Trade?