To flush or not to flush

I just got an 08 5.7 4x4. Carfax shows the transmission fluid was changed at 48,000. Maybe it's been done again, maybe not. It now has 166,000. I'd like to replace the fluid. Drain whatever comes out and replace with new stuff in the same amount? Or use the cooler lines to exchange all the fluid? Maybe just drain and fill then make that call when I actually see the condition of it? From what I read, the bolts on the pan can be a nightmare so I'm thinking of not taking it off. I loosened the check plug just enough to have some come out on my finger. It's dark, slight red tint, and doesn't smell new but I wouldn't think it smells burnt

 

Drain and fills are what most people recommend, but if your confident and can pull up the pan temp on a gauge, the cooler lines to do a full swap is the way to go

 

Kinda risky..

I did this in my escape, drove fine right after I changed the fluid. Next day, cold start, wouldn't shift to 2nd, jumped from 1st to 3rd. Over a couple days I was able to force it to 2nd by manually shifting to that gear. First 5-6 1-2 shifts when cold were real harsh, then drove fine. I hypothesized that the new fluid mixing with old caused some dirt to precipitate and slightly clog the valve body passages, but not enough that they wouldn't eventually clear with driving.

I did another 3 drain and fills and now it drives like new, each d+f made the trans shift better and more willing to grab 2nd when cold.

You might find the same thing happen to you. Just don't do a power flush, that's much more likely to jam up your transmission to the point you might only have 1st gear, if any gears at all.

Up to you, it's a shaky place to be in. Personally, I would try changing it. But think it over very well first.

 

Want to add, I would do a basic drain and fill, not use the cooler lines at all. Any pressurized fluid going in/out could cause serious problems since the old fluid is so dirty.

 

Poppycock, the cooler lines aren’t using or adding any excessive pressure to the system, the tranny pump is doing all the work, same as normal when the engine is on.

 

So how does that work to remove the old and replace with new? Run old fluid out sending line from trans, while siphoning new fluid to sending line to cooler?

 

You let it spit out into a bucket, and then run a fill hose to the fill port and pour in fluid. Again doing it this way, your not asking your tranny to do anything it isn’t used to doing everyday of it’s moving life

 

Fill fresh at the trans and pump out old at the disconnected cooler line. People recommend 2 qts at a time so you don’t run it low on fluid.

 

Yes I understand the use of the internal tranny pump is normal, obviously. My hangup is the procedure of simultaneously extracting and adding fluid in a controllable and measurable manner without making a huge mess, or starving the trans pump, which I am assuming works similarly to an oil pump, driven off the input shaft of the trans?

 

I’d drain the pan which will remove four then add that and an extra qt back, then turn truck on allowing 2 qts to drain, shut off, add 2 qts, turn on etc. You’d want someone working the key while you’re watching fluid. Doing it this way you’ll never be more than a qt low and you’ll have to do this cycle 5 times or so to get all the old fluid out.

 

Gotcha. Not a bad system. Not sure if I'd elect to replace all the fluid immediately just because of the difference in lubricity of new vs old tranny fluid, I don't know if its so big of a difference that it might cause the trans to slip, since it's used to old fluid.

 

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

Here’s a write up that I followed which hopefully will explain it better for you.
My tundra has the sought after transcooler- that made it very difficult to get into temp check mode range, should have done it on a warmer day

 

It sounds like you’ve done this before?

 

I’ve only don’t partials on the Tundra since I’ve had since new but I’m getting ready to do this on the LandCruiser.

 

Our Sequoia had 110k miles on it and we decided to take it to my mechanic for a proper trans flush using the 'dialysis' machine. Glad I did it too cause she needed it.

 

Saw this same post on TW

 

Tundra and an LC.. thats a rare group...my man...

BTW that link is great. But I think there is a video on how to do a full drain fill of the old Tundra (Gen 1) on youtube as well that explains the process.

Well i guess someone has shown how to do the full drain fill on the Tundra 2nd gen as well.. here's the link below.

MY ONLY Comment from the video would be --- instead of manually putting the transmission on check mode via the OBD2 paper clip jumper.. just get a OBD2 reader. Plug in the correct formulas (which you can find online if you search) for your transmission pan and torque converter and check the Transmission temperature that way. OBD2 Reader can be had for $5 bucks from aliexpress. Get the bluetooth 4.0 one so both iphone and android can read it.

Here's the link to the one I use. https://www.aliexpress.us/item/3256...2RLrSkh&gatewayAdapt=glo2usa&_randl_shipto=US

 

LandCruiser is the wife’s - I may have had some influence in the decision.

I like to tell people the only thing better than a Toyota 5.7 is 2 Toyota 5.7s.

 

I just had a drain and fill done on mine with 218,000. The first few days after the d/f I noticed that the truck had a really pronounced down shift when braking. You could Really feel it shift down in every gear. I decided to wait and see, so after about a week it smoothed out and is running like a champ now. I'm thinking that it took a while for the tranny fluid to really blend in once it was changed. I'll be doing another drain and fill in about 20k miles. 2007 C/M

 

All I know is I bought three used Yotas with 96k+ miles. '05 Tundra, '07 4Runner, '08 4Runner. All three I took right away into Groove Toyota in Denver for a full flush and fill via the cooler lines. All have to tow, so that was a no brainer. The Service Advisor and Tech just considered it routine, been there done that. 18 qts exchanged, $350 and four hours later all was smooth. Dealers don't buy exchange machines if they don't work and cause problems.

 

This is the right method. https://youtu.be/ej_6BZpK3gg
I did mine at 200,000 miles. Records showed it had the first d/f at 120,000 miles. I did the above process 3 times to get clean fluid. Trans worked perfectly afterwards with smoother shifts.

 

I just don't understand why one wouldn't use the BUILT-IN leveling procedure to ensure you have the correct amount of fluid.?

I am of the opinion that you can never know if the previous level was indeed correct. Faye even mentions that this service had been done before (by someone else) and there is a difference in volume depending on temperature.

Just taking the time to do the proper procedure removes all of these variables which could throw the level off.

I have done several drain and fills at this point, and I still do the leveling procedure EVERY TIME. Even though I am quite sure the level is correct to begin with.

Different strokes I guess.