If you're concerned about changing fluid on an old transmission, then first do a drain/refill and see how the transmission responds.

Many ATF fluid exchange machine really use the cooler line flush method as in DIYs. Except they measure the system fluid more accurately.

 

I did do two and it responded fine but it's still coming out pretty dark brown. No perceived issues with slipping gears or anything. I'm not exactly sure what it would feel like, but I assume when the transmission changes gears, this occurs when I see the RPMmeter drop back down to 1,000, that if there was a problem, that's when I'd feel some grinding or jumpiness. And I do not.

 

I'm not sure why @tanyak is concerned about the drain/fill technique. That is probably the easiest way to change ATF and is even easier than an oil change! Cooler line is a little trickier IMO but still very doable. And I'm not sure why you would need metal tubing - just get some clear vinyl hose to slip over the ATF lines.

Regardless, my vote is for drain/fill. Just drain it, measure it, and put the same amount back in. Drive for a few weeks and repeat. Drive for a few more weeks and repeat.

And you only need a new crush washer on the last drain/fill (although some people reuse the old one regardless of how many drain/fills).

 

I've done two drain and fills and it's easier than an oil change, yes, but I still have to jack the car up, put jack stands, chock the rear wheels, get under the car, get a few drops of ATF on the driveway even at my best, fill up a drain pan, hold the drainpan up over a container with a funnel, get a torque wrench, set the torque wrench to 13 foot pounds, reset the torque wrench back to zero.

I've done it twice and I know it's really not that big of a deal. Just writing out the steps because if I understand the DIY guide correctly, then all I would have to do is:

1. Use pliers to remove the tip cooler line clamp from the radiator. No jacking the car up is needed, I believe my model Corolla the top cooler line is the tranny exit line.
2. Slide the hose off the radiator.
3. Plug an adapter into the line that has a hose running into a container
4. Start the car, let it run for 30 seconds. Confirm the volume drained, re-add the same volume. 1 quart increments is ideal.
5. Reconnect the cooler line, reconnect the clamp.

No jacking the car up, no getting on the ground, no dripping ATF, no pouring ATF from a collection pan into containers, no torque wrench, no risk stripping the bolt or pan.

Seems like the best way to do it, unless there's some risks I'm not aware of and you get to change all of the fluid in one shot, instead of only changing 1/3 of it each time and having to wait for it to mix with the old.

 

If already two drains and refills and the result is fine, then sure go for the cooler lines.

 

I've now done three of them and it's still coming out a but dark but I can finally see some reddish hues to it!

 

GM had a bulletin years ago to only do drain and fills and never any other way.

"The use of external transmission fluid exchange or
flush machines is not recommended for the automatic
or manual transmission. Use of external machines to
replace the fluid may affect the operation or durability of
the transmission. Transmission fluid should only be
replaced by draining and refilling following procedures
in Service Information (SI). Refer to Automatic/Manual
Transmission Fluid and Filter Replacement."

https://static.nhtsa.gov/odi/tsbs/2020/MC-10173416-9999.pdf

 

Thanks for sharing this bulletin! I was wondering if the method listed here, which involves:

Connect cooler exit line to a collection waste bottle
Start the engine
Wait until 1 quart fills the waste bottle
Stop the engine
Fill 1 quart into the transmission via dip stick port
Restart engine
Repeat until fluid comes out clear

I think the difference between this and the professional flush machines is that they are pressurizing the new fluid to push it in. Whereas this method is relying solely on the pressure created from the tranmission that goes into the radiator. And new fluid is filling the pan through the dip stick port via gravity.

Is this still considered a "flush" and could it be dangerous?

 

Is the transmission shifting hard? Any codes for the shift solenoids?

 

I dont see the check engine light but I do not own a scan tool. I do own a cheap OBD2 tool.

I dont think it's shifting hard. I look at the RPM-meter and when I'm accelerating and the RPMs drop backdown to 1000 is when I think the shift occurs, and I dont feel anything jarring.

The only thing that's a bit hard is shifting from Park to Reverse. Under normal circumstances, I dont feel it because I shift it from Park into Drive in one smooth motion. But if I try to move it slowly, it's hard to shift between P and R but once in R, it's very gentle pressure to go into the other gears.

The parking brake is on during this P to R shift because I saw a video from Car Care Nut a few years back that suggested always putting parking brake on to protect the transmission parking pawl.

 

What you're doing is how oil change centers like Valvoline do for transmissions - external pump - just drain-fill - start engine for about 8 seconds and repeat until fluid drains translucent which is usually 4 drain fills and about $110.

 

I'm in (almost) complete agreement with this approach, with just a few differences (noted below). I used it every 60K with my Previa, which ran perfectly to ~320K (>500k km), until the rusted body became impractical to sustain.

As he says, using the transmission's own pump is perfectly gentle, so no stress on seals. That leads to one of the ways I part from his procedure: Because it only pumps at maybe 3 liters/minute, that gives you plenty of time through all the gears - say, 10 seconds each - while it is flushing, so you can clean all the passages.

That in turn leads to my other difference with his procedure: once set up, I did the flush from the driver's seat (the hose was long enough that I could see the bucket), so no assistant needed.

My final difference is that, in the setup before running the flush, I usually just flushed the screen with clean ATF rather than replacing it, but I did replace the screen once or twice.

 

Because it only pumps at maybe 3 liters/minute, that gives you plenty of time through all the gears - say, 10 seconds each - while it is flushing, so you can clean all the passages.

Are you cycling through the gears with your foot on the brake for 10 seconds each?

How do you handle adding more fluid in? I think it would be bad if you let the pan go dry, so there's some risk in draining 1 quart, adding 1 quart. I wonder if you could run it with extra fluid, add 1 quart, then remove 1 quart.

 

Some just shut the engine off between fills. It's safer that way.

 

I never found a need to do that. By the time the ATF runs clear at the bucket* (which is when I shut off the ignition), the level is down to within a quart of where it should be. The flush itself just takes a couple minutes, and really works nicely.

[* One of the great satisfactions of this process is seeing the ATF exiting the hose turn from brown to clear cherry red over a span of maybe 10 seconds.]

 

I've used the post @tanyak mention when mine was 200k without any issues after.It was having the stuck lock up solenoid issue,now 340k still working fine.

 

The TSB is meant to keep you at the dealer. Drain and refill and repeat is safest. Too much new fluid and flush chems can be the death of the glue in the clutches. Flush machines are not perfect, especially if the machine's pump doesn't keep up with the drain flow. The front pump runs dry and the trans is done. It's a great way to sell extra service. Having said that if trans fluid is really bad it may be the only way to go. Once. My Avalon used bought at 140K had silver and black fluid Thank you Fred Anderson Toyota Raleigh NC. 8 gallons of Maxlife later it stays red, but I still do a drain and refill once a year. Very old mechanic here. Did hundreds of machine flushes. Once a year saw flush kill a trans. Back to topic, once the fluid is reddish, get a gasket and drop the pan. Clean the screen and add a few magnets to the pan to catch any gear shavings. Used wheel gearing grease on the gasket to hold it in place and as a sealer. Never ever use RTV unless that is the gasket and use RTV from the dealer or one made for transmission. There are alcohols in trans fluid. PS MAxlife IS WS. It is for every trans that uses red fluid except for Chrysler. It is MerconV, which everyone started using when torque converter clutches came along and it was the best anyone came up with. Fell free to howl about only using OE. Which is fine if you get a deal. And the barrel at the dealers I worked for do not say Toyota, it said Warren Oil MerconV.

 

::slow clap::

Well said and excellent information.

This is exactly what I was thinking as I read through the comments here.

Flushes can kill. I've heard that not only can it starve parts of lubrication, but it can stir up sediment that would otherwise have stayed put, out of the way and out of play. (that's second hand info and could certainly be wrong)

Beyond that I also work and have worked in dealers for a long time now. Most fluids are produced by a handful of companies (just like batteries). Reputable brands work for me, even with coolant there are good aftermarket alternatives. Some parts OEM is a must, but for the most part I think fluids can be swapped for non OEM just fine.

 

No worries, just do the full DIY flush and be done with it. The drain and fill method is nonsense. I’ve done the DIY on 3 different Corollas several times and it works

 

A trans intake line cannot suck fluid out of a container.

The fluid is being pushed by the trans pump throughout the trans and into the pan - where as you said in the DIY you saw - they drain the pan - close it up - turn on engine for about 8 secs refilling the pan with the next amount of dirty fluid and then repeat repeat repeat till the fluid drains translucent - Done.

 

. . . The fluid is being pushed by the trans pump throughout the trans and into the pan - where as you said in the DIY you saw - they drain the pan - close it up - turn on engine for about 8 secs refilling the pan with the next amount of dirty fluid and then repeat repeat repeat till the fluid drains translucent . . .

If I understand you correctly . . . I don't think that's right: The whole point of opening that cooler line is to push dirty ATF out of the system and not let it return to the pan. That's why the process works so fast: It's just a one-way push up from the pan and through the system, then out to the bucket.

 

I agree with what you're saying - all I was saying was the intake line cannot suck in fresh fluid - it can only go in thru the normal openings (dipstick or fill hole). I have seen folks connect a hose to the intake line and keep filling a large funnel while draining from the output line and having the engine run to keep pumping out the old - is that what was meant?