Questions about the process(es) of changing automatic transmission fluid

Messages
664
Location
new jersey
on my Tacoma 4 speed auto transmission(non -sealed) I just bought a case of genuine Toyota T-IV ATF off EBAY seller and did 4 pan drains and refills, much cleaner and easier than puling off a cooler line and ended up with the same results. I just drained every morning COLD and measured and replaced thru the dip stick hole the same amount for 4 consecutive days each day I drove the truck to get it to operating temp. and torque convertor lockup then repeated the COLD drain and refills, was a breeze without major incidents.
 
Messages
5,673
Location
Ohio
Say a car owner changes his ATF. He is using the remove, measure, replace system. His transmission is warm and he removes say 5 litres. He then replaces the 5 litres with new, but cold ATF.
Will the expansion of the warm fluid, compared to the cold, play a factor here? Will adding the same quantity of cold mean too much is added?
I've tested this on multiple vehicles and the amount of "thermal expansion" is negligible. It's not worth even considering the difference plus, transmissions allow for a range of fluid anyway, not a dead-nuts, spot-on volume.
 
Explain this please. What goes into bypass to cause old fluid from the previous change to get pumped into your car?

Here's the bypass explanation from the T Tech manual:
"The BYPASS FUNCTION simply allows the machine to loop within the system when all the new ATF has exited the cylinder. This function allows the operator to walk away (work on something else, etc.) when the machine is running, without being concerned about service completion. When the piston reaches the top of the cylinder (old ATF has displaced all of the new ATF), the Bypass Function is automatically engaged. This causes the fluid now in the system to be forced into a loop through the vehicle and the T-TECH unit. At this time there is no longer an exchange of fluid and the loop will continue until stopped by the operator by turning off the vehicle."

It seems that the old and new fluids never intermingle with these exchange machines. http://jiffylubecs.gradepoint.com/en_us/doc/T-Tech_Manual.pdf
On the machine I used to use at work, it had some internal capacity that was separate from the dirty / clean sections for recirculating. You could see the color change when it went into bypass. Plus you still had everything that was in the lines , etc. If the fluid in the vehicle before yours was black, the fluid circulating wasn't clean for sure.

When you got it hooked up and started the vehicle, it was in bypass mode with your dirty fluid circulating until you hit the exchange button. Then it would start letting out the dirty and introducing the clean fluid. So there were times of circulation through the transmission of what was in the machine, hoses, etc. Now if the car before yours had really clean fluid, contamination was minimal for sure. But if it was black or a filthy power steering system, then you def got some of that dirt. While I think the setup was great for severely neglected systems. I personally wouldn't use it on my car since I am good about maintenance. It just isn't needed and poses too much of a risk of getting other stuff into my vehicle. It sounds great in theory, but the actual process is less than ideal. The machine usually left the system 2-3 qts low on fluid as well. It had to be topped up after the process was finished.
 
Messages
453
Location
England
I've tested this on multiple vehicles and the amount of "thermal expansion" is negligible. It's not worth even considering the difference plus, transmissions allow for a range of fluid anyway, not a dead-nuts, spot-on volume.

Hi Hall
Thanks for helping.

I do not understand this. When i look at the fill chart it seems to show quite a difference in the level when the temperature increases. I am obviously misunderstanding something here.

The level increases by 40mm from 77f to 167f.
3_0L%20TURBO%20DIESEL%20WH%20XH%20NAG1%20FILL%20CHART.jpg
 
Messages
5,673
Location
Ohio
What volume of fluid does 40mm on the dipstick represent ? I've done this with (4) different cars - '14 Fusion (2x), '08 G35 (2x), '12 Accord, '12 Civic. In all cases, the ATF was hot (vehicles were driven for 15+ minutes and drained fairly quickly after driving). I transferred the fluid to a 5-liter bottle and marked the level. With the Fusion and G35, the temperature was 150º F (66º C) or higher. I let it cool down to ~80º F and for all intents and purposes, the level didn't change. Did I measure the volume or weight using lab-grade equipment ? Nope, just a clear, plastic bottle with a black marker mark and an infrared thermometer. Do I allow the fluid to cool to measure how much to replace now ? Nope...
 
Messages
105
Location
Vancouver, WA
Apologies if this is a stupid question.

Say a car owner changes his ATF. He is using the remove, measure, replace system. His transmission is warm and he removes say 5 litres. He then replaces the 5 litres with new, but cold ATF.
Will the expansion of the warm fluid, compared to the cold, play a factor here? Will adding the same quantity of cold mean too much is added?

I ask, as my W5J400 needs a dipstick and a means of measuring fluid temperature. Easier to replace just what comes out if tranny is operating just fine.

Thank you.


You need to buy a dipstick or make one DIY.
I used to own an ML320 which has the same 722.6 transmission, no dipstick like you. I bought a dipstick from MB dealer for about $40, you can buy one much cheaper from Amazon/Ebay. Here's how to make one yourself.

At least the ATF on this MB 722.6 tranny expands quite a lot at its operating temp of 80 degrees C. Its ATF capacity was 9 qts.

MB_dipstick.JPG
 
Messages
453
Location
England
What volume of fluid does 40mm on the dipstick represent ? I've done this with (4) different cars - '14 Fusion (2x), '08 G35 (2x), '12 Accord, '12 Civic. In all cases, the ATF was hot (vehicles were driven for 15+ minutes and drained fairly quickly after driving). I transferred the fluid to a 5-liter bottle and marked the level. With the Fusion and G35, the temperature was 150º F (66º C) or higher. I let it cool down to ~80º F and for all intents and purposes, the level didn't change. Did I measure the volume or weight using lab-grade equipment ? Nope, just a clear, plastic bottle with a black marker mark and an infrared thermometer. Do I allow the fluid to cool to measure how much to replace now ? Nope...
Hi Hall
I honestly do not know what volume the 40mm increase in fluid is. It looks a pretty big sump pan so i guess it could well be a significant amount. Note that i say guess.
The answer of course is to temperature check and use a dipstick. However, the thread title Questions about the process(es) of changing automatic transmission fluid and considering the owners who use the drain, measure and fill method, i thought my question was valid.
 
Messages
453
Location
England
You need to buy a dipstick or make one DIY.
I used to own an ML320 which has the same 722.6 transmission, no dipstick like you. I bought a dipstick from MB dealer for about $40, you can buy one much cheaper from Amazon/Ebay. Here's how to make one yourself.

At least the ATF on this MB 722.6 tranny expands quite a lot at its operating temp of 80 degrees C. Its ATF capacity was 9 qts.

View attachment 56734

Hi Sparky.
Thanks for helping.
Yes, it does seem to expand a lot with a temperature. Hence my query as to adding cold fluid when hot is removed.
 
Messages
1,300
Location
ottawa
Thanks for all the responses, guys. I've done the DIY cooler line thing, I always wondered if running until it sputters is bad.

Also thanks for clarifying that the fluid exchange machine uses the car's own trans pump to do the work.

Some background on why I ask: I take my car to the track and after about 10 track days the car is shifting at way too high of an RPM. This means that all the fluid is degraded so I want to flush it entirely because all the stuff that's in there now is bad.

In future I would consider partial changes as routine maintenance, but this time I need to exchange it as completely as possible.
Your trans might have changed the shift points from your aggressive driving...all auto transmissions are not adaptive. That is they change / shift on how your drive.
Your fluid might be ok.
However, I personally would drain and fill twice - if it were my car.
 
Messages
18,343
Location
NH
What volume of fluid does 40mm on the dipstick represent ?
I wonder... maybe the fluid in the sump has a large area, until that sump is full, then maybe it necks down? So when adding fluid, the apparent measured level would change slowly as filled, until the large cavity was full--then additional fluid would show quick change. Think of a 2 liter soda bottle. Once you get close to the top, it starts to fill very quickly. Now add in heating effect and then fluid level might change "a lot" as it heats up.

Personally I've never understood why transmissions should be so picky about fluid level. Missing 2 or 3 quarts then yeah, problems. On an 8 quart system, give or take, what's a quart either way? Not only that but they used to have a remote ATF cooler and those I thought only circulated when the thermostat (if so equipped) allowed fluid to circulate.

Anyhow. IMO 40mm can't be correlated to anything without know the transmission, a mm of movement could be a mL at the top of the dipstick and that same mm of movement on the dipstick could be a quart on the other end, for a particular transmission.
 
Top