2019 Tundra transmission drain and refill

For those of you who drain and refill your transmission fluid do you subscribe to the put in what comes out method or run the truck until it is at 99-111 degrees and use the overflow plug? The reason I ask is before removing the drain plug I removed the overflow plug and drained right at 2 quarts. This told me that using this to check the fluid when it was warm wouldn't work. Of course my overthinking did it anyways and after replacing 4 quarts of cold fluid with 4 new quarts of cold fluid I warmed the trans fluid and monitored it with my scan gauge II. When I opened up the overflow plug fluid came pouring out just as it had during the initial drain. I reinstalled the plug and ended up draining out just shy of 1 1/2 quarts. Luckily I ordered 6 quarts of Toyota ws fluid so I put 1 1/2 back into the transmission.

My only thought is that maybe my transmission is missing the small plastic straw that threads in before the overflow plug.

What are y'all's thoughts?

 

The truck was off?

 

Truck was off when I checked the overflow. Should it have been running? If so, in Park?

 

Yes and yes. Make sure you have cycled through each gear (R, D, S1-S6) a couple times with the engine running between adding fluid and checking the level.

 

https://youtu.be/NUAuGmDGntY?si=e9huyt4Lu-7qFBxl

This video outlines the proper procedure very clearly.

Many people will get in here and just say "drain it cold, from the drain plug. Measure what you get out, and replace with exactly that."

I'm too OCD to do that method, and so I did mine in the same way this guy does in the video above, except for I used a scan gauge to check it at precisely 101°F (again I'm super OCD). But I also recognize that just draining and refilling the amount drained will likely work 99% of the time.

That being said no method suggests opening the check valve first before draining and subsequently filling the transmission. So don't do that again.

 

I was mostly worried about being able to remove it after the drain and refill. Similar to making sure you can remove the fill plug before removing the drain plug!

 

I get that, next go around just crack it open for a quick second, as you really only need to ensure it will crack loose, and not even loosen it enough to let fluid out until you're ready to check the fluid level.

 

I did the drain & fill of the transmission fluid when I installed an external trans cooler (the GCS kit).
Once I drained the transmission (little less than 4 qts came out), I refilled using about 5.5 qts, to account for the trans cooler install (added hoses, etc).
Then turned the engine on, shifted thru the gears until the trans pan temp reached 90F, then put it in park, waited for it reach 99F to do the "wait for trickle".
I also used Scanguage II for the temp monitoring.
I'm glad that I did this procedure (and will do so next time), because I think that my transmission was slightly underfilled from the factory.
It's anecdotal, but I feel like the truck shifted a lot "smoother/faster", especially when driving at first in cold temps. Previously, I'd feel a slight hesitation between shifts, esp in lower gears.
Btw, I did this last year when I had about 30K miles on the truck, should have done it sooner, but the truck is shifting great now.

 

As stated, the truck must be running when checked at the correct temp. Also there is no straw in the pan, I dropped mine once, this is what it looks like.

 

I’ve done it both ways. I did the temp check procedure when installing my cooler, and I did the “just put back what you drained out” method when doing my 60k drain/fill service.

I’ll probably stick to the latter method from here on out. Two reasons:

1. Fluid volume is hardly different at all hot vs cold (or ambient).

2. The method they give us to check it is pretty imprecise IMO. It just comes across as “meh, when it’s a trickle (whatever that is), replace the plug”. They know these transmissions are stout and are good with +/- a quarter or eighth of a quart.

Draining ambient temp trans fluid into a measuring container and putting back the exact same amount of fluid at the same temp seems far more precise to me. If you want to be OCD about it, do it in the morning with your new fluid having sat outside overnight so they’re at the exact same temp.

 

I think fresh fluid also shifts noticeably better too. when i did my last drain/fill i thought it wasn’t shifting perfect, added a half quart of fluid and it became spot on. I think there is a decent amount range in fluid level that it will tolerate

 

All good points. Here's another thought I had though:

Typically when doing the temperature-specific method, most folks will add an extra half quart above what they drained out. Then as you warm up the transmission and shift though gears there's an extra 1/2 quart of clean new ATF circulating. After draining the "appropriate" amount out of the check valve you may have slightly better diluted the old ATF than someone doing just a typical drain and fill. But that overall effect is still probably quite negligible.

 

I also make sure vehicle is level prior to performing this procedure, especially my stock Tundra with nose down attitude.

 

Alright fam, bringing this one back up. In my previous truck I always took it to the dealership for this one, as I'd read about a pin, temp, this and that.

Having watched the CCN video, this seems trivial on my '21. My question is the whole DNDNDND flashing D sequence vs ambient temp fluid (I like the idea of leaving the fluid out, hell right below the truck bottled of course). Now here's my thought though, the shifter sequence moves fluid around to some degree, be it old and more come out, or just moving it in general. I've got a few more thousand miles before I do this but wondering what you all do/prefer

Here's another kicker for me, my driveway isn't flat so that part has concerned me as well with the shifter sequence method as you guess at what the spot of a trickle is.

So given my circumstances, what would the group suggest here?

 

Maybe find somewhere flat you can do the job? Or just fill back exactly what you manage to drain out. Also I'd use a scan gauge or other similar OBDII scan tool to monitor the temp for the level check procedure versus the weird shift sequence song and dance

 

Hey there. It's me again

Want to spend some more money on your Tundra?

Look into the Scangauge III to be able to view all your gauges live as well as read and reset codes. It's a great tool to have! Especially for your transmission maintenance.


Just to add, I believe your '21 doesn't have the stock cooler so you wouldn't need to worry about the pin but I'd double check that too be certain. Also with the SGIII you wouldn't need to do the paperclip/jumper in the OBDII step since you'd be reading the gauge.

 

Aight, so lets say I have access to TIS, ScanGauge still needed? I don't have any desire currently of displaying an SC all the time, so it would be more of a use it as needed tool.

Now assuming I have either, what temp are we looking for here? CCN gives a range, what does everyone shoot for? How fast does the temp climb? I'm debating this as a solo job, or a phone a friend job. Best of all, I have time but trans is my next 'major' service.

Also, with TIS/SG, what about the not to level driveway?

Lastly, what about the BT OBDII dongles and an app? That one isn't about cost, as it is convenience. Being under the truck, at the ready for the appropriate temp range.

 

When I drained mine I was surprised on how little drained out.

 

" I think that my transmission was slightly underfilled from the factory "
Same here

 

I'm not familiar with TIS, so I can't say for certain. I have a Scan Gauge II (the simpler, smaller cheaper one), and I like that it's much smaller than the Scan Gauge III pictured above. It's also nice to be able to hook it up when I plan to tow and monitor trans temps during that towing trip.

When I did this I waited for the pan temp to hit 101°F. I believe the range CCN gave was 99-111°F, so I just picked a number in there. Note that it took probably 10 minutes of idling for the trans to get to that temp.

Oh and there's so few tools involved (Allen wrench for check plug, ratchet, 14mm socket for drain plug, and i think 17mm or 19mm socket for fill plug, some tubing and a funnel) in this job, that I'd just find somewhere level to do the work. Hell pull up to an Oreillys parking lot and knock it out

 

So, one thing about SGIII I dislike is the large display, that was until I saw this install pic.

That I could get behind, as well as I tow occasionally. Also, the wife is in a 4Runner so an investment in tools isn't a concern as much as some screen/monitor mounting. This install pic may settle that for me.

 

Hmm, not gonna lie that's a pretty cool spot but accessing the lower part of the screen to toggle through menus would be a bit difficult. I would probably cut a bit of that plastic and have a thick backplate to push the SG out. Also not to mention the wiring. You'd need to get a long enough cable to reach your OBDII port. Curious if this guy actually installed it there or if it's just a mockup and doesn't actually have the wiring go thru the headliner, down the A-pillar, thru the dash, and into the OBDII.

Is this photo from a post on this forum? I'd like to see how they did it.

Btw, this is the backside of the SG..


So you'd have to cut a hole in the sunglass holder to run the plug thru.

 

Extremely valid points to consider. I hate with a passion cutting up my interior, wiring, etc and would look at having OEM replacements stand by, or alternatives which has me going back towards the BT, OBDII setup. On the wiring, I read that CAT6 ethernet cable is all I need, and I'm swimming in various lengths due to my career

 

I went another route... and this one lets me.... errr, I mean, my wife watch Netflix on road trips.

 

This ^^

Is why I like the Scan Gauge II. I can hook it up in 5 seconds, hit the road and monitor my temps/etc on that trip. Then when I'm done towing I can stow it away in 5 seconds until needed again. No cutting, no tablet behind my steering wheel or blocking my view past the A-pillar

 

Just use a cheap IR thermometer, ita not an exact science.

 

I've got one of those too, but don't trust it. In the CCN video he shows an IR vs what the system see's and the temp difference could put you out of range.

 

I can see your point, and even though I have a MagBak case, it's never on the dash. All of that going on would bother my OCD.

I've got a few months to decide what I'm going to do here, just wanted to get in front of it. The job overall seems pretty straightforward, and a variety of methods or tools can be used and it's highly likely I'm overthinking and overcomplicating all of it.

Appreciate everyone's feedback thus far.

 

I can see where the temp of the metal outside could be quite different from the actual fluid inside.

Yeah the new head unit was killing a few birds with one stone. Better sound quality, Android Auto, better NAV, the screen mirroring, front camera, and the gauges.

I wanted to be able to monitor trans temps while towing, not so much for the drain n' fills. I just pay my mechanic to do 'em.

Now that I work close to home I'm only driving 5-6K miles/yr. so I don't mind paying him to do 'em every 5 years or so.

The Veepeak BT OBD scanner and app is a popular choice on here, and might be a logical method for your needs.
With that you can get separate temp readings for TC and pan.

 

Yep, and good points. I'm already '21 so have Apple CarPlay, wireless dongle and tech12volts sub/box/amp so I'm good on the HU replacement for the time being.

And to your point on the BT OBDII and app, it would accomplish exactly what I'm after here, and I can take the phone under the truck with me to be quick with the timing of temps, and fluids. Decisions decisions as usual.