Transmission- 5 Speed automatic write up with pics for second gen 4 liter trucks

@gearcruncher got a suggestion of what I'm seeing here? Truck has sat in the garage for the last 2 months. Moisture build up internally, or radiator mixing fluids? Or just the result accelerated wear and now's a good time to replace? Fluid wasn't exactly milky, more like graphite so I'm leaning more towards internal wear vs water contamination. I only observed the discoloration once 99% of the atf had been drained. It appeared red in color while it was draining.

2006 A750F with 195k on it.

 

Signs of moisture for sure . .
Does your antifreeze have oil globules floating in it ?
Have you taken the truck for a swim ?

 

Not sure. I'll have to check the radiator. No swimming, just parked. I'm thinking now's a good time to swap in that spare trans I have.

 

We see this on Hilux's, the stock transmission cooler in the bottom of the radiator cracks and coolant mixes in with transmission fluid.

 

Opinions on adding a drain plug to the torque converter? I'm skeptical about what may have entered a torque converter I got with the transmission I'm swapping and looking for a way to flush out anything that may have contaminated the torque converter. Will it cause the TC to become out of balance? Would it be as simple as adding another drain plug 180° off to counteract the imbalance? I'd rather not have this one cut open to keep costs down.

 

You can do it but gotta be super careful .
If I was going to do it , 1/8th national pipe thread plug rather than the standard 3/8 plug and its got to be shallow .
I have drilled many converters in the past in order to install a flush plug but not on a locking converter . Never caused any imbalance
In the old days , we didn't have a converter clutch to contend with . In today's newer cars and trucks , we have to deal with a converter clutch dampener and its located inside directly behind the mounting pads where your converter bolts to the flywheel . Looks the same as a flywheel in a manual transmission application . Even by over tightening the converter bolts to the flywheel can create a converter lock up chatter . I believe this is why there are no converter flush ports on the newer vehicles .

As an alternative ,
You could take the converter to a trans shop and have it flushed . They have a special flush machine strictly used for flushing converters or start the truck and give it a flush before driving the truck .

Forgot to mention : run your vent line up to your dash . These transmissions are famous for water intrusion

 

That's what I was reading on a Corvette forum that Google returned when I searched TC flush.

 

Also, once the TC pumps atf out, what's the next path/route the atf takes? Directly to the filter/screen and then into the pan?

 

The converter is by far the hottest operating mechanism inside the transmission. Once the fluid is inside the converter , the fluid is sent directly to the cooling system to be cooled .
From the torque converter to the cooling system then back to the transmission pan

 

Thanks again, you've been a big help with all of my transmission related problems.

I'll soon find out if that 2012 t4r a750f will work in my 2006

Replacement trans from 2012 t4r


Old trans from 2006 Tacoma.

 

So far I've got about 200 miles on my transmission swap using a 2012 t4r a750f with manual shift tcase behind it and no problems from install to driveability. I even used the t4r BH stamped bell housing which I was hoping wouldn't bite me in the ass and be just slightly different than the Tacoma bell housing. So unless I'm gloating too soon, it would seem any a750e/f from any vehicle Toyota offered it in, will interchange where another a750 was. You're not locked into the year range that Toyota says will only interchange with your year truck.



My 06 a750


The 2012 t4r a750. Note the Japanese writing, I'm assuming this a750 is manufactured by Asin Warner in Japan? Since the t4r is manufactured in Japan.

 

Update: Just finished a 400mile road trip consisting of mostly highway travel, over 2 mountain passes and speeds of 70-85mph and not one issue. Trans shifts like a dream with TC temps peaking at ~205°F on the longest grade and averaging 180°F the rest of the time. Truck was moderately loaded with camping gear, and just me solo in the truck no trailer. Next time I wouldn't hesitate to source a A750F from a 2015 Tacoma with low miles for a swap.

 

Last month I took my Supercharged 2012 with 105K in for a long overdue trans flush. While it was there I had the tech install TransGo’s SK A750 kit and the A750 Boost. https://transgo.com/products/a750e/

I wasn’t having any real problems with the trans. The shifting was a bit lazy with the SC and it was time to change the fluid. The kit is noticeable but not harsh at all. The shifts are quicker and more positive. It really shines in downshifting to pass. Overall the transmission just seems “smarter” and better finding/staying in the correct gear while pulling the gear longer with a load. I just did 1300 mile road tip, with day out in the Oregon Dunes. Aired down, long hill climbs, while enjoying all that glorious sea-level boost and the trans stayed cool and pulled hard.

 

https://youtu.be/t73jM6mT8sU

 

So I accidentally found out today that when you have 4H engaged, the transmission won't go into 5th/OD?

On Saturday I was starting to climb a friend's steep driveway so I stopped and threw it into 2LO, FJ case swap, climbed the grade and once at his house I went to pull it out of low range and shift back into 2wd when the weld on my shifter broke but I knew that I had managed to get it out of the low side and into the high side. I just wasn't sure at that point if it successfully came out of 4wd and into 2wd since I also don't have the front drive shaft installed at the moment.

Fast fwd to this morning and afternoon while commuting to and from work, I noticed I was still in 4th gear since the tach was showing 4k+rpms on the freeway doing ~65-. I did everything I could think of to help persuade the transmission into 5th and it just held 4th gear. Once I got home again, I crawled under and sure as s, it was still engaged in 4HI.

 

@geargazer I making alot of assumptions here, but do you know if any shops local to socal that you would recommend for general transmission servicing. 08 taco with 195k miles.

 

Tacomas shift into 5th and lock up while in 4x4 . At least mine does
My first guess would have something to do with the temperature sensor and I would scan for codes to begin . Overdrive is the first thing that gets cancelled for very minor glitches .
Temp sensor , brake switch , PRNDL switch , TPS sensor as well as 4th gear switch all come to mind .
I hope everything continues well with your test transmission . You did a fantastic job on that truck

 

Are you trying to speak with me ?
Send me a pm with your actual location and I will hook you up

 

No codes present at this time stored, or pending that my obdII scanner is seeing, P code related at least. what's weird is that once I got the tcase back into 2wd it had no issue shifting into 5th, and I didn't shut the truck off to do it. It was still idling on the shoulder as I crawled under and manually moved the shifter linkage by hand. I'll take a look at my TPS this evening, it's been a while since I cleaned it, and also the throttle body.

 

Hey all! New-ish owner of a 2010 Tacoma, bought it back in June of this year with 210000km, now has 213000km \ 132000miles. Been driving it on and off issue free till the cooler temps came up here in Canada.

I don't know the service history of the truck, so I had it burned in the back of my head to change the transmission fluid however I just didn't get around to it till recently... Here's what prompted the fluid \ filter change.

The truck has always had a noticeable shift change from 1st to 2nd, more randomly after warmed up vs cold. However the cold prompted a new issue to arise. A slip or flare (rpm jump) hard shift between 4th and 5th in the cold. When I noticed this I parked the truck and did a flush out of the transmission fluid. I pumped out 13l of old, brown fluid and now have a nice redder fluid coming out (I followed the how to guide on here). The pan was relatively clean aside from the normal residue found at the bottom of the pan (no chunks or anything alarming)

After the fluid change, I did a transmission relearn in techstream. I drove it to work, the temps now are even colder than when they were when I first had the issue arise. Good news is the slip \ flare shift seems to have gone away, however I have a very very noticeable hard shift between 4th and 5th. The shift between 1st and 2nd remains the same.

Monitoring the transmission fluid temps driving to work, that being a 20min commute. The fluid is getting up to about 109 degrees (43°C reported by torque) so it's barely getting into the normal operating temperature to see if the issue slowly gets better with heat.

Now I plan to keep this truck for a long time, so I'm looking to try to resolve and save any damage done to the transmission by having this hard 4th to 5th shift.

My thought is in the distant future tget the sonnax shift zip kit and add Lubegard near future make a grill cover for my truck to try and boost the temps of the fluid ... However I'm not finding any answers as to if this will resolve the issue I'm having... Read up on others having similar shift issue but no answer.

Thanks for any input given in advance!