2001 Prius transmission failure

Superb work by Scott, Art, and of course Hobbit for the finding. My favorite image was the Jackson Pollock approach for applying loctite to bolts!

Bittersweet through that Art's won't do this again, with the full accounting of reasons why.

Tempting to suppose that the original O-ring installation could be an underlying cause in other failures as well. Tempting but unsupported, and obviously it's a long way in, to try and find out.

However I would like to put a suggestion out for discussion. It *is* possible to measure the transmission fluid pump flow without disassembly. I say this not because I've done it, but rather that 'IFixEm' (who has not posted at PC for a long time) revised my NHW11 to have an outboard transmission fluid filter. He built a few others, as well. It may be that he fully described the design here at PC (time for an archives check...).

Anyway, do the mod, and the fluid is pumped through an external piece of hose, and then back into the case. In my example, the outboard filter is spliced into that hose. But just as easily, a flow-measurement device could be put there instead.

Having used them for other purposes, I'd suggest something along the lines of:

http://www.coleparmer.com/catalog/product_...asp?sku=3270352

might be suitable, and easy to 'log from'. The stated 10 cSt limitation is pushing it, but if we are only really interested in relative values...

With or without a published spec for fluid flow rate, such a fluid flow mod on a few NHW11 could establish the typical range of values. Any found with much lower flows would deserve closer inspection (or a hasty sale!).

So would it work? Or importantly, could a similar design be used on (the much larger population of) NHW20s?

 

IFixEm's description of the transmission fluid pump modification

http://priuschat.com/index.php?showtopic=19667&hl=

unfortunately the images do not appear for me. Anybody know how to access those? I tried (without success) at web.archive.org

You'd think I could just take a picture of 'my' NHW11 but it is in New Mexico and I am quite far away.

 

<div class='quotetop'>QUOTE(tochatihu @ Sep 14 2007, 11:52 PM) [snapback]512880[/snapback]</div>

It would be unusual indeed for an assembly error to create a pressure loss that somehow did not cause a unit failure until 80K.

 

<div class='quotetop'>QUOTE(jk450 @ Sep 15 2007, 12:00 AM) [snapback]512924[/snapback]</div>

I would have supposed the very same, prior to this new info from Art's. Now I am willing to consider the possibility that it might take quite a long time for such an intial assembly error to cause a total system failure.

The majority of internet-reported NHW11 transmission failures have occurred between 50k and 150k miles. Most of those have been dealt with by Toyota, under warranty or generously afterwards. No forensic info from the gimmes has been made public. I really wish that someone would prove me wrong in that assertion! We'd love to know what's going on in there!!

I used to claim that NHW11 Prius trans failures were 1/10,000, then 1/000. I am being pushed by recent data towards 1/100. Still that would be relatively low compared to some conventional automatic transmissions. However, as a tireless cheerleader for Prius technology, I feel that my ankles are getting tied.

So, can we test the lubrication function of NHW11 and NHW20 transmissions? Apparently so, either by flow rate (as I suggested earlier here) or by pressure as Bob Wilson has proposed in the Yahoo technical group. The NHW11's have a bottom pan, so it would be much easier to determine if the o-ring was done correctly. The NHW20 lacks such access, but (based on my great confidence in Toyota's upgrading), I'll bet anyone here a buck that the NHW20 has been notably improved in that area.

So, for those who are now negotiating compensation for transmission failures, keep doing what you're doing, and maybe mention that there *might be* a *little tiny* design and assembly issue in NHW11. No problem for them to demonstrate that your o-ring was done just right.

Everyone else, the vast majority of Prius drivers with no such problems: I repeat that precautionary transmission fluid changes are the only card you can play. Unless of course somebody offers to measure the pressure or fluid flow in your transmissions. Stay tuned.

 

<div class='quotetop'>QUOTE(tochatihu @ Sep 16 2007, 05:46 AM) [snapback]513270[/snapback]</div>

I would like to think you are correct, but the drawings from the 07 Service Manual don't support your position:


[attachmentid=11486]

[attachmentid=11487]


Can I have my dollar now? Or should I wait until the first failed O-ring is found?

Hopefully, Toyota has fed that info back to the factory, so the individuals installing the strainer tube can guard against this problem.

 

<div class='quotetop'>QUOTE(jk450 @ Sep 15 2007, 05:00 AM) [snapback]512924[/snapback]</div>

Hi Jk450,

Given that these transmissions have shown 250K + mile durability in taxi service, 80 K for this problem does not seem wrong as long as some oil gets pumped into the gears. Its just that there is not enough volume of flow for proper sump cooling to take place.

I have had some professional experience with constant displacement lubrication pumps. Sucking air does not completely stop oil flow, but does drop the output pressure dramatically. So, any chips or things in the flow pathways would choke off flow. Remove the air intake, and static no-flow pressure can be as high as 1000 psi. Which would push most chips right through any oil passages.

The machine I was working on had a oil pump filter that leaked air. We could not get the flow sensor to engage. The sensor was a spring loaded ring magnet that was pushed back by the flow, so that it operated a reed switch. There was clearance around the ring magnet for oil flow. It was designed so that when there was high veloicty flow the drag was enough to push the magnet back against the spring. Still, there was oil coming out of the lube points, which were crimped tubing that directed oil into larger gears. The mechanic had plumbed the filter on the intake side of the pump, which it was not designed for. Suction resulted in the gaskets in the filter not being seated. Putting the filter on the output side, it did not leak, and there was dramtically improved pressure. Which easily operated the flow sensor.

This is the same situation as in the pictures shown. The screen is summersed in oil, and the o-ring is above oil level. So, if its split it would alow air bubbles to stream in with the oil flow. The air would compress in the constant displacement pump, and output pressure would be limited dramatically. But a small dribble of oil could still flow. Which would lubricate, but not cool the transmission components.

 

<div class='quotetop'>QUOTE(VAFairfaxHybrid @ Jun 1 2007, 04:14 PM) [snapback]453533[/snapback]</div>

My 2002 Toyota Prius
lost power and shut down on a Southern Calif freeway
in Spt. 2007.
It acted like I ran out of gas but I had a full tank.
Pressed accelerator- no power.
The red water temperature light came on.
It was towed to the dealer.
Diagnoses, trans axel malfunction
replaced HV transaxel
also replaced drive belt and tensioner.
74000 miles on the car.
No more warranty (60000 mi).
My car is maintained to the highest levels with regular service.
After much nagging
Toyota said they will help me with half the costs of the part.
After adding the labor charges, this ordeal costs ME $3490.74
I am VERY disappointed and
it could have been a very dangerous situation.
I sent the NHTSA (National Highway Traffic Safety Administration)
my information about this ordeal and Consumer Affairs also.
And I'm opening a case with Toyota
1-800-331-4331

 

Hi Jhprius,

Yours was not the first car to coast to a stop on the side of a highway after 74K miles of usage. And it wont be the last.

The only case you have is if you have the old transmission, and can show the specific defect that led to a premature failure.

74 K miles , unfortunately, is not premature for the other cars out on the road today. And with the compensation that Toyota gave you, the price is in-line with the repair of other cars today.

So, your going to have a hard time showing any damages.

If that happens to my Prius I will be very disappointed too however. But you know we all take risks when we buy things. And any other car could have had just as short as transmission life. Car transmissions do not last forever.

 

Sorry to hear, jhprius. There is little we can do after the fact, but it would be great if you can post all the details such as diagnostic trouble codes that were reported.

The red water temperature light would be extremely rare, and I'd like you to confirm it was that and not some other light. Edit - was it the one I've circled?

[attachmentid=11521]

Drive belt and tensioner also rare or possibly not reported in the internet Prius discussions. I assume you mean the one in the engine?

I am involved in compiling cases of reported transaxle failures, and it is very sad to add new ones. The best that can come out of it would be a fix or preventative maintenance to reduce their occurence in the future.

Nothing would please me more than for Toyota to provide this themselves, but if not it would have to come from the user community.

 

<div class='quotetop'>QUOTE(jhprius @ Sep 17 2007, 07:26 PM) [snapback]514006[/snapback]</div>

I certainly hope you don't mean the folks at http://www.consumeraffairs.com/

If that is who you are referring to, then you've just lost a lot of credibility.

 

I've been following the discussion as well as I can, though I know absolutely nothing about cars, so the technical discussions are over my head.

I just wanted to let you know that the red water temperature light was indeed the first warning light that came on when I experienced my problem with my 2001 Prius (at almost 100,000 miles). After the red temperature light came on, then the others came on, too. Every time I stopped and turned off the car, the red temperature light was the first one on again when I restarted. (I stopped at several service stations, where some very nice folks helped me make sure I had plenty of coolant.) I was able to continue driving, though the car was not responding normally. When I took it to the dealer the next day, they said the transmission was failing. (I gave more details & the codes in my previous emails in this discussion.)

We finally made the hard decision to have the transmission (or whatever it really is called) replaced. Toyota kicked in $2,000 -- I was unable to convince them to cover more of the repair. The final cost to us was $2,900.

To say we are disappointed is an understatement. We're just crossing our fingers that there are no other unexpected major repairs in the near future, as we plan to drive this car until it dies. I realize that any car with 100,000 miles will have repairs in its future, but we just didn't expect this from the Prius so soon! We're still hoping for at least 200,000 miles before it dies, but time will tell. We really like this car, but we are definitely nervous about it now.

I hope my experience is useful to others out there. Thanks to everyone for all the help & advice. I'll let you know if anything else develops with our car.

 

I've gone back and forth with Toyota corporate and they will not cover the "transmission" failure on my 2001 Prius. It's unfortunate that they will not recognize what is looking more and more to be a defect, and cover it accordingly. I am unwilling to sink another $5K into this car (91K) since it's clear that Toyota will make every effort to wiggle out of warranty coverage in the future.

My confidence has been shaken in both Toyota's quality, and especially their commitment to their customers. So, what can I get for a 2001 Prius which needs a transaxle replacement? Can I get more from a salvage broker?

Thanks to all here who have provided great information.

 

<div class='quotetop'>QUOTE(pkamm @ Sep 23 2007, 09:20 PM) [snapback]516741[/snapback]</div>

I would try to find a used transaxle in your case. Assuming that the rest of the car is in good condition.

The value of your car would be whatever a similar Prius would sell for minus the cost of repair.

 

Try to get them to give you an extra good deal on a new Prius they have in stock and trade it in. You may come out better this way if the dealer is interested in having and keeping a happy customer. Plus they will repair it cheaper for the used car dept. Or maybe they will just charge it to the warranty of another vechicle they own.

 

Pkamm, I am sorry. A few years ago the 'floor price' for a classic Prius 'with problems' was $5k. More recently I have seen them (body damage) go for about $4k, so there has been some decline in value. By all means treat such numbers as miminums!

Have little idea what a salvage vehicle dismantler would offer, but my intuition says 'less'.

Have you given any thought to installing a salvage vehicle transaxle as dogfriend suggests.

Amhobby's suggestion only makes since if you have not 'given up' on Toyota. Perhaps you have, though I hope not.

 

<div class='quotetop'>QUOTE(tochatihu @ Sep 24 2007, 05:11 AM) [snapback]516793[/snapback]</div>

Toc,

Thanks for your advice.

I will be writing an article about my experience in this situation and offering it to both the New Times and Tribune in San Luis Obispo. I will also offer it to a family friend who writes regularly for the LA Times to see if he finds it news worthy. And, I will be posting it in several online blogs and news outlets.

My experience with Toyota corporate and Toyota San Luis Obispo has been disappointing. I did not expect this kind of treatment. I thought that Toyota would be especially interested in providing customer care to the folks that took a chance and became early adopters of an automotive technology still in its infancy. It appears they do not particularly care about those folks who helped put the Prius in the public eye. That's unfortunate.

I believe that we will eventual find that there was indeed a defect in the early transaxles. But Toyota has determined that it's not cost-effective to admit this and cover these expensive repairs. So I will warn the class of 2001-2003 of these pitfalls, and suggest that Toyota's commitment to its customers may not be what it's built up to be.

Customer loyalty is critical these days. The hybrid market is getting quite competitive. I hope Toyota doesn't learn this lesson too late.

-pk

 

I'm beginning to research recalls and complaints on the NHTSA website about the 2001 Prius. I'm wondering if the recall in 2006 could have anything to do with the eventual failure of the transmission. Search here for 2001 Prius recalls:

http://www-odi.nhtsa.dot.gov


I encourage all you gen 1 Prius owners who have experienced a transmission failure to file a complaint at NHTSA so this defect can be documented.

 

PKamm,

It is too bad that your transmission failed. However, it failed out of warranty, so Toyota is not "wiggling" out of their warranty responsibilities. People expect Toyotas to never fail, but sometimes they do.

To me, hearing a story about a Prius whose transmission failed out of warranty, and having Toyota refuse to pay for the repairs does nothing to harm my faith in Toyota. The warranty has a term limit. If you want a longer term, you can buy an extended warranty.

 

<div class='quotetop'>QUOTE(Winston @ Nov 1 2007, 06:00 PM) [snapback]533596[/snapback]</div>

Winston,

Your point is a good one. However, some parts had a 60K warranty, and others had a 100K warranty. Toyota said that the entire transaxle needs to be replaced, but it's not clear where the failure occurred, or how. When a recall is issued, the warranty makes no difference.

 

<div class='quotetop'>QUOTE(pkamm @ Sep 25 2007, 01:44 AM) [snapback]517288[/snapback]</div>

Sometimes part X fails, and sometimes part Y fails, but I haven't seen a narrow pattern of failures that points to a specific defect. And these cars are now four to six years old.