ATF drains & metal particles in between clutch plates

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I was watching a video by Chris Fix dealing with questions about changing the ATF. At this point (https://youtu.be/o690DovjDAc?list=PLvKbarVtwhUvKCEzK79P2ex9rWVRxVcTl&t=327) he talks about potential problems when changing transmission fluid when the atf is dark and hasn't been changed in a very long time (which suits the condition of my Sienna—I am pretty sure the fluid has never been changed before yesterday, and it was very dark).

Assuming this idea is correct, are these metal particles circulating freely throughout the ATF, or are they only lodged in between the clutch plates themselves? If this means anything, when I drained my ATF in the Sienna, some of it got on my fingers (both with and without a glove), and it felt very smooth, not gritty at all.

I'm suspecting that these particles are most likely only lodged in between the clutch plates--if the trans was depending on a steady stream of them flowing through the fluid, then merely a drain & fill (which would eliminate a fair amount of those particles from the fluid) would be enough to bring about slipping.

Reason why I'm asking, is that the fluid went from very black, to a dark grey, and I'm planning on another drain & fill, or even a pan drop & filter change, in a few weeks or months, to put more new fluid into the system. This is most likely the first ATF drain & fill ever for the Sienna.
 
Isn't it designed to operate unfiltered where the fluid simply recirculates and it's designed with all this in mind? Is an ATF service even part of the scheduled maintenance? I thought that Toyota didn't even recommend anything other than inspecting (and replacing as necessary) unless used for towing.
 
So worn clutch material in burnt and spent ATF in a transmission that was never serviced and never a problem could actually be what is stopping the transmission from slipping and failing. Changing it out and introducing clean fluid to the system can cause it to fail, since the worn clutch material is stopping it from slipping. That makes sense. New fluid doesn't have worn clutch material in it. What I gained from that video is to continue doing what I have done for many years, change the ATF every 25-30K miles, so the fluid never gets bad enough to be holding things together.
 
If wear material is all that's keeping the transmission from not slipping the transmission has some real issues anyway and on its way out, I don't share his opinion.
 
He's a talented video maker, not an engineer. He's wrong. He makes videos about what he googles up on the internet - which is of course SO reliable - and regurgitates it. The advice you saw there was worth what you paid for it - actually less.

First, putting new fluid by flushing it all at once is not harmful. Pumping new fluid through a transmission is NO different than the internal pump circulating fluid on it's own, unless you use a high pressure pump. Which is not common. In fact, an easy flush can be done at home using the internal pump. There is a filter akin to an oil filter to take out damaging material. New fluid simply isn't going to find some magical pile of beans, residue, or dirt to dissolve and re-flood the unit with.

I take it these ideas are tossed around by people who've never rebuilt transmissions. If a clutch plate is so worn that it can't work with CLEAN fluid, it won't work with dirty fluid. Tiny bits of material suspended in the fluid just physically can't provide enough friction material to hold two worn-out plates together - not gong to happen. A simple thought exercise should help convince you of that:

a) If it were true, then friction discs would never need replacing - the dirty fluid would supply enough material to get them to lock and not slip. Not true.

b) A corrollary example would be fixing a manual transmission slipping clutch by sealing the chamber, then filling it with dirty ATF, maybe some fine sand mixed in. Not gonna work.

Transmission don't have combustion by-products or any nasty things generating filth inside. People extrapolate from their experiences with engines and don't think it through and come up with half-baked guesses like this.
 
^ this. If changing the fluid lunches your gearbox, it was dead anyway. Anecdotal evidence here, but I flushed filthy, probably original fluid out of my 240 at 152,000 miles and the transmission is not only still alive, it's significantly better.
 
Originally Posted by demarpaint
So worn clutch material in burnt and spent ATF in a transmission that was never serviced and never a problem could actually be what is stopping the transmission from slipping and failing. Changing it out and introducing clean fluid to the system can cause it to fail, since the worn clutch material is stopping it from slipping. That makes sense. New fluid doesn't have worn clutch material in it.


This is 100% false.

By the time the friction discs are SO WORN down to the point hat you need "clutch material in the oil" (!)
to provide a transfer of power, that trans is fully baked.
 
What year is the Sienna? I had a 98 and that filter is referred to as a strainer. Cleaning the pan and strainer or replacing the strainer should remove a lot of the goop that is sitting in the pan.

You can max life ATF for the tranny fluid
 
2006. Yes, I used maxlife. It seems to have a very good reputation, especially among people with my cars/transmissions, so I chose that fluid; and it does meet the Toyota T-IV standard.

Originally Posted by JC1
What year is the Sienna? I had a 98 and that filter is referred to as a strainer. Cleaning the pan and strainer or replacing the strainer should remove a lot of the goop that is sitting in the pan.

You can max life ATF for the tranny fluid
 
what Oro_O and 240_Ed said. Exactly. 100% full of win.

My co-worker's father's uncle's barber's gardener changed the fluid in his transmission and it didn't even make it out of the shop, so changing the fluid is bad.
crackmeup2.gif
 
if your transmission is in such a state that a flush or new fluid starts causing slip..... it was worn anyway. I suppose you might get a few more miles out of it if you hadn't changed the fluid but I think your splitting hairs here. These kinds of videos are so unscientific as to be basically worthless IMHO.
 
Sorry, it is a 2005, as can be seen in my sig.I mistyped above, but couldn't edit it.

Originally Posted by JC1
What year is the Sienna? I had a 98 and that filter is referred to as a strainer. Cleaning the pan and strainer or replacing the strainer should remove a lot of the goop that is sitting in the pan.

You can max life ATF for the tranny fluid
 
Originally Posted by Linctex
Originally Posted by demarpaint
So worn clutch material in burnt and spent ATF in a transmission that was never serviced and never a problem could actually be what is stopping the transmission from slipping and failing. Changing it out and introducing clean fluid to the system can cause it to fail, since the worn clutch material is stopping it from slipping. That makes sense. New fluid doesn't have worn clutch material in it.


This is 100% false.

By the time the friction discs are SO WORN down to the point hat you need "clutch material in the oil" (!)
to provide a transfer of power, that trans is fully baked.

Did you watch the video? My point was based on the video. Let me put it another way. If the transmission was operational, [not necessarily good] before the service, and failed immediately, or shortly after, what was conveyed in the video makes some sense.

My comments about how I service my transmissions would always maintain clean fluid in the system, so wear particles aren't what is keeping the clutches holding. And filled for life, is a bunch of garbage for anyone who plans on keeping a transmission for the long haul.
 
I have taken apart Magnefine transmission filters and do not see much in the filter media but there is normally some metal paste on the magnet. If you rub it on your fingers its like Never-Seize.
 
I think the dirty fluid and particles don't help with clutch packs, but they might help with sealing the solenoids that direct the oil pressure, since the fluid is full of material and it starts depositing in various places. With new fluid the deposits can now be suspended in the fluid again, so the hard surfaces start to clean up.

Clutch packs are held together by fluid pressure, so if the pressure cannot be maintained, it can create a slipping effect.
 
Originally Posted by KrisZ
I think the dirty fluid and particles don't help with clutch packs, but they might help with sealing the solenoids that direct the oil pressure, since the fluid is full of material and it starts depositing in various places. With new fluid the deposits can now be suspended in the fluid again, so the hard surfaces start to clean up.

Clutch packs are held together by fluid pressure, so if the pressure cannot be maintained, it can create a slipping effect.


I often thought that might be the case too, along with slowing down leaks, maybe? After watching the video, I thought the "grit," for lack of a better term might give spent clutches a little tooth. Removing that gritty fluid takes that tooth away. Either way the transmission is shot, but with that extra tooth it might have extended its marginal life for a little while longer, had the fluid not been swapped out.
 
it seems the Thesis of this video is: If the transmission fluid has not been changed (ABUSE from black and burnt ATF), AND it is on its last leg, don't change it because the particulates will help to increase lockup and reduce slipping.

The particulates floating around will be composed of small particles of steel, aluminum, and the composite clutch material. It is the Combination of the fluid's FM characteristics and the surface (face) material that determines the overall dynamic coefficient of friction.

At this point the FM in the fluid is probably shot so the final dynamic coefficient of friction has been highly modified anyway.

As to the particulates in the fluid, he is assuming that the aluminum, steel and composite clutch material floating around will "fill in the spaces" between the worn wet clutch faces and extend the lockup for awhile.

He is making the assumption that the particles will embed themselves between the clutch faces and reduce slipping. Worn and "glazed" clutch faces will not do this since the glazing situation is similar to the skating of ice on glass. So the only thing the particulates can do is to reduce the clearance somewhat between the steel plates and glazed clutch surfaces.

Secondly, a fluid with heavily-laden particulates will interfere with solenoid and actuator operation, both slowing their movements and interfering with sealing (i.e., leakage).

Changing fluid Early to about 1/3 of the OEM's OCI recommendations, seems like a proactive way to prevent burnt fluid and glazed clutches.

One thing about changing out degraded fluid that has gone past its service limit with fresh fluid, is this will tell you if your transmission needs service.

I had rather change out the fluid and detect any problems now and have them corrected, than to be out in the woods with my grandsons and fire up the vehicle and it doesn't move.

Can you say, "Long Hike?"
shocked2.gif
 
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As long as the transmission isn't already slipping or shifting funny changing the fluid and filter is not going to hurt.
I've changed fluid on transmissions that it came out as dark like used engine oil and they had 0 issues afterward if anything there was shifting improvement.

If problems are encountered after a change then it was going to happen anyway.
 
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So far, if anything, shifting seems quicker and every bit as smooth, if not smoother, than it was before. The biggest change is that I notice (if this isn't a matter of perceiving what I want to actually be the case) that the Sienna is not taking as long to move from one gear to another now.


Originally Posted by StevieC
As long as the transmission isn't already slipping or shifting funny changing the fluid and filter is not going to hurt.
I've changed fluid on transmissions that it came out as dark like used engine oil and they had 0 issues afterward if anything there was shifting improvement.

If problems are encountered after a change then it was going to happen anyway.
 
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