Transmission Flush - drain/fill method vs trans cooler method?

I was planning on doing a transmission flush by dropping the pan, replacing the filter, and then doing a sequence of Drain and Fill's - 15 qts total.

But I've heard some talk about doing a transmission flush by draining from the trans cooler? If that's right, is there an advantage to doing it that way?

Also, is 15qts a good amount for a Drain/Fill flush or can a case be made to run a little more through?

(I am at 125k miles and have never drained the transmission. - I fell for the rumor that sealed transmissions don't need it.)

Finally, given the high miles, should I consider doing another filter change in a month or so in case grime comes loose from the first flush?

EDIT: Ok, sounds like the coolant return capture technique is what I want, especially given my advanced miles (extra dirty fluid). Anyone know of good videos demonstrating this process? All the vids I've looked at so far just drain from the pan.

Thanks much!

 

Your good with your plan with dropping pan and replacing filter. Also 15 qts is the right amount to purchase.
Just master the temp check mode procedure before you do anything and your golden.

 

Temp range is like 97-115F, I believe.

In this video the guy shows that a laser thermometer on the pan is only 4-5F short of his internal sensor (that's a custom install, I guess).

Given that the variance that it is short by is only a fraction of the full temp check range, wouldn't a thermometer be adequate as long as it reads a little over 100F?

 

I checked mine the temp way the first time on my 09...figured out that if you drain it ..it holds 3.2 Quarts

 

I always drain pan change filter put everything back then drain about 4-5 more quarts through the cooler lines with truck running. I try to get as much dirty fluid out as possible. It's doesn't make sense to do drain and fills and only drain about 4-5 quarts out and add in new.

Would you drain only 3quarts of engine oil and leave 3quarts of dirty oil in your motor, on a oil change??

 

What made you change your mind? Usually you measure what you remove if dropping the pan and filter method and add that back. I have a 2015 and just hit 100k a d haven't done mine and when I asked they said not to it's a sealed unit

 

It’s actually easy to do it the right way, sure there’s a little learning curve but that’s why you master the procedure before you do anything. It’s easy. It just takes a little patience and a little will in order to not be intimidated.

 

the drain and fill drain and fill mixes old fluid with good.

If you drain/drop the pan, fill with good, then start the truck to pump old fluid ~2qt at a time (so you dont suck air) then you are pushing old fluid out with very little mixing.

For you @125k. Drop the pan, clean the magnets, replace the filter screen, button back up. Fill trans with 4 quarts of fluid (toyota ws, or maxlife if preferred). Then proceed like stated to pump 2 quarts out at a time from the return line between the trans cooler and trans at the front of the truck (obviously filling back in 2 quarts every time you pump out 2).

Do this for a total of 12 quarts (4 initial fresh in the pan - then 4 sets of pumping 2 quarts out filling 2 qts at a time) and you will have fully replaced the ~11.something quarts the system holds.

Let truck sit on a level surface and cool off completely (hours). Put into temp check mode and let heat up to proper temp, then pull the check plug. You will probably drain out ~0.5qt of trans fluid.

Protip : get 10ft of 3/8 vinyl tubing. Set it out in the sun so you can uncoil it easy (they always come in lil rolls that are a PITA to make straight when cold) as well as all the transmission fluid you are going to use (makes it flow better with a lil heat). Then run the tube from the engine bay down the firewall on top of the trans to the fill plug on the side of the trans. Cut to length up in the engine bay insert a funnel.

This makes a pseudo dip stick tube so when you need to fill the trans, you simply open the fill plug, put the one end of the tube in the hole and pour the transmission fluid in. No pumping with hand pumps or electric things. No mess no fuss.

 

Run from that service department. EVERY fluid has a useful life. I would love to hear what the transmission being a sealed unit has do to with the useful life of ATF. The warranty and maintenance guide (pp45) calls for replacing the ATF in an auto trans after 60k miles if the customer tows or regularly carries heavy loads. It is in the guide as an optional service for special use cases and there is a procedure in the tech manual.

 

Thanks for clarifying the advantage of this method of draining old fluid from the transmission cooler.

I think I definitely want to use this procedure because of the high miles I have ... I want to minimize the risk of dislodged debris clogging valves and such inside.

If anyone knows of some good videos demonstrating this method, I'd appreciate any leads.

Thanks all.

 

So I found this guide on the forums here:

https://www.tacomaworld.com/threads/diy-full-flush-for-automatic-transmission.68462/

But... I am unclear from the pictures which radiator line to disconnect. The first picture with the red arrows seems to imply that one should disconnect the right side (when looking toward the back of the truck). This is the line that runs along the front-ward edge of the front of the truck frame.

But the second picture that shows the line disconnected appears to be the the left side line (when looking toward the back of the truck).

So I'm not clear about which line to collect the old fluid from. I need a video guide if possible to help me be confident that I'm understanding the procedure correctly.

 

I did the trans cooler method at around 100,000 miles. Sorry no videos and I don't recall which line is the return. It also helps to have a remote starter so you can start the truck from underneath while you watch, then shut it down as soon as the flow just starts to show some air. Refill, then repeat a few times.

But I did not drop my pan and replace the filter because when I went to do that, I noticed that the pan bolts were in really bad shape from rust and it was unlikely that I could get them off without some creativity and damaged bolt extraction tools. I needed to get the thing back on the road so that got deferred. Just posting this so that you have a look at that before you get too far along and plan accordingly. Me? I got a set of new bolts from Toyota but I have not got back to dropping the pan. Trans is still working perfect at 136,000 miles.

Another pro tip: get a ScanGage 2 and program it to read trans temperature. Makes hitting the mark easy peasy. It's also nice to monitor trans temp (and whatever other 3 parameters you want) in real time while you drive.

 

I was planning on just doing 2L at a time to minimize the risk of ANY air.

Seems to me like getting air into it could be bad? Would it cause any malfunctions? Or would the air bubbles get cycled out after a minute or two?

 

Which is bogus. Trans fluid is not indestructible, it breaks down and can bog your gears. After having a gear bog/clunk issue I had mine changed, and seeing what mine looked like coming out at 70k I will now be doing it every 50k miles. Also did the filter and magnet.
IMO if you really want the truck to run forever you should absolutely change it. There are many things that can impact how quickly your fluid breaks down, such as driving habits, towing, heavy tires, armor, etc. Maybe bone stock you can make it to 100k+ no problem, but why risk doing irreparable damage to your truck?

 

Interesting, when I did mine at 100k miles it looked brand new. But I don't tow or wheel. But I agree, chemically speaking it is a good idea to replace, even if it looks good.

 

Gotcha. I got the same spiel from the toyota tech after I started developing a rumble from between 2nd and 3rd gear (AT). I run heavy tires and armor plus a RTT, so I figured it had to be the trans fluid. Not to knock the techs, but sometimes they just parrot the handbook if they don't have a lot of field experience.

Drained, filled, and the problem is gone.

 

I use IR readers on my Toyota/Lexus models. I now have an UltraGauge in my Tacoma and the temp variance is 1-3 degrees. And I’ve seen comparisons to TechStream readings in Camry and 4Runner forums with similar results. So, yes, 100 degrees is a good temp to aim for.

I don’t know of a video showing this exact way. I also forget which hose is the return line. I end up using my IR gun - the cooler line will be the return line. I can check and get back to you later on.

Yes, air in the transmission will vent out the breather tube. They will clear out while setting the ATF level.

 

do yourself a favor, only do 2L/2Qt at a time so you dont suck air in. Air in a hydraulic system is bad. Why try to make the job 5 min quicker by pushing out just a little bit more to save yourself from having to do one more cycle on a multi thousand dollar transmission.

FYI, its about 7-10secs per quart pumped out at cold idle speeds which gives you plenty of time. Get a gallon milk jug / clear water jug empty and mark half quart increments on it. Set under the truck and with vinyl tubing you can route the ATF return line to the jug. You can start the truck standing outside the open driver door. look underneath as its running filling and shut the truck off easily just before it hits the 2qt mark.

 

I think this one shows it pretty clearly; its the one that is slightly angled to the side, instead of directly towards the rear of the truck:


But, if you're in doubt you can either trace the line from the transmission. Or just disconnect one, get a drain pan, have someone start the truck for a few seconds and make sure you see fluid coming out. If nothing comes out, you likely have the wrong one.

 

The first time I did mine. Disconnect the return line going to the transmission. Measure what comes out of the pan and add that much to the pan. I believe mine had 4 qrts. Take a gallon jug and measure 3.5 qrts. The key is to not run the pan dry. Put the return line in the gallon jug. Start up the truck. Pump 3.5 qrts out. Shut off the truck. Add 4 qrts. Repeat till the fluid is bright red. Reconnect the return line.

I use the fushion app and a kiwi 3 Bluetooth OBD reader. There are custom pdi’s to get pan temp and convert temp.


I did add this pan 1.5 years ago. It did add 3 extra qrts of fluid.