3rd Gen Automatic Transmission Fluid Level Check DIY

this is my second Toyota with this weird no dipstick checking procedure. I myself know how to check and or change the fluid. when I checked the fluid on my Jan 2019 built Tacoma, when I pulled the check bolt, no oil came out, none. I had to add around 12 oz to make it trickle out correctly, at the correct temp range, so I think that Toyota still may not be filling some of them correctly.

 

There is a range, do we know what the range is?

 

Not necessarily. If fluid is coming out of the overflow pipe, then the fluid level is at the maximum acceptable level. There is also a minimum acceptable level, and that's generally 0.5 qt (~16 oz) below the maximum level. If you had to add 12 oz to bring it to the maximum level, then in theory your fluid level was within the acceptable range.

 

Idk. If there was that big of a min/max why would they be so adamant about the temperature?

 

Expansion of fluid

 

Yeah exactly.

 

Because temperature significantly affects the volume and therefore height of fluid level in the transmission. If the primary way of checking fluid level right now is by volume, using the overflow pipe as a reference, then the fluid temperature has to match whatever fluid temp the engineers calibrated the height of the overflow pipe to.

Think about it this way... if the fluid was cold then the fluid height relative to the overflow pipe would be low and you would end up adding more fluid than you needed until. Obviously vice versa for a fluid temp that is too high...

The ideal way to check would be by weight... actually draining the transmission and weighing what came out. Temperature would not affect this.

 

I believe the temp is 98 to 115 degrees for the correct temp it's posted above a few posts

 

No I get that. But if there was a min max of half a quart why bother accounting for the thermal expansion of the oil in the first place?

 

All this is true there are still quite a few variables one of those also being what the individual persons interpretation of the " trickle" draining out of the pan is

Next issue would be one of the technical guys on here explain or give a example of the expansion per quart ratio it's far above my equating skills but there is a formula

But I would imagine it's not by very much or there would be quit a issue with bottles of a low viscosity style fluid would be popping or swelling up noticably especially on a hot day in a garage ?

 

Exactly. So why do we assume there would be such a huge min/max? Toyota calls for a pretty exact procedure to measure. So I'd assume the min / max is a few Oz. Not half a quart haha.

 

The be all end all would have been a simple check at cold fill plug like a transfer case since it's a "pressure " transmission and a simple dipstick would not suffice

As soon as I do the drain measure and weigh I will post unless someone beats me to it

Also curious if the 2 wheel is different than the 4x4

 

But define cold! Cold for Canada, or cold for me in AZ? That's much more than the 20* variance that the book calls for. Keep in mind this just my understanding of it all. I could be way out in left field.

 

Another easy experiment would when "cold" just pull the check plug before pulling the drain to see how much drains out

 

I'm probably gonna do another drain and fill in a month or so. Maybe I'll try this. Theoretically, if u did a drain and fill will the trans was at 190*, u could get a little more out of the pan. Negligible probably tho

 

Also, if u hit the quote button in the bottom right it'll copy my reply and tag my name too.

 

Dont burn yourself on the hotter fluid!!!

 

The reason we “need” this complex process is not just thermal expansion. The transmission has different amount of oil trapped in different passages and galleries depending on what it was last doing when you shut off the truck. It takes ages for all the oil to drain back into the pan. Maybe even days if the truck is sitting.

Toyota gave us a method to check the level that takes 1/2 hour if the tech knows what he is doing.

The “cold level” approach would have instructions like “park truck on level surface for 4 days, remove full plug”.

it’s actually better the way it is.

 

Excellent write up and instructional OP, going to do this when I have the time to check my fluid levels as I noticed the harsh downshift when slowing down then giving a little pedal to speed up. Also, if anyone can chime in. How does one use the kit below:

https://www.ebay.com/itm/Toyota-Lexus-Sealed-Transmission-Fluid-Replacement-Kit-/222731930378

From the looks of it, would it be worthwhile to do this? Pros and cons?

I have the Torque app, seen it mentioned that it may work with getting the auto trans temp to get the desired overflow drain point. Any thoughts?

 

Huge FYI!!!!!

The 2020's DO NOT have Pin 13 installed in the ODB connector!!

If you look at the top row, you'll see that #4 looks different than #3, and #13 is different than #14.

I pulled the port out to see the wiring from the backside. The bottom row from above is closer.

Good thing I found this out AFTER I added 16oz to the trans!