Help! Did i destroy my transmission?

2016 Limited 4Runner
Did a drain and fill, i have done this once before as well. All Toyota fluids and washers.

I drained 3 quarts and 2 cups, refilled 3 quarts 2 cups plus a couple of squeeze's extra from the pump to allow for the level check. Did level check at 104 F, fast flow then slow trickle, torqued up all the bolts. Truck drives fine changes gears when expected and is fine under load.

Came back after test drive to check for leaks around the bolts, bolts and drain check are fine but i notice oil near where the two pieces of the transmission are bolted together.

I don't know if it was there before, but i know that important area as the two pieces of the transmission meet together, now I'm concerned, did i damage the transmission?

Photo's attached.

Thanks,

 

Spray it clean with brake cleaner and then check again after a 20 minute drive .

 

You are fine. Meaning you did a text book drain and fill. That was probably already there. As the person above me said, spray some brake cleaner on it and then watch it. But you did the drain and fill 100% correctly.

 

That leak is probably completely unrelated to your fluid change.

There is a seal on the transmission that goes around the transfer case input shaft, and if it starts leaking, transmission fluid leaks into the empty space between transfer case and the transmission case, then leaks out of that seam. The seal shows up as brown in these pics.

 

Thanks guys. You think this is something that needs to be looked at / repaired now or shall i keep driving see how it goes? Thanks.

 

Yes, it should be repaired eventually, years down the road when the leak gets bad.

 

Based on the photos @McSpazatron posted - I am familiar with that kind of seal. It could be a double lip or a single lip seal. Hard to tell from the angle the picture was taken.
These seals are fragile - meaning the lip that rides the input shaft is delicate. The rest of the seal assembly is just there to support the lip. Based on your profile, you have a 2016, but how many miles? And has the transfer case or the transmission ever been removed?

The seal can be replaced with the proper tooling - a remover tool and an installer. The remover tool essentially destroys the existing seal assembly, but if you intend to replace it, it doesn't matter. Anyway, I asked if the transfer case had ever been removed because those types of seals are very easy to damage by nicking or cutting the lip when removing or installing the input shaft.

The leak may, or may not get worse. Your transmission would only be damaged if enough fluid was lost. As others have said, I would clean the area and then keep an eye on it.

 

So a few things OP,

1. when you started the job was the unit showing the same leaks? Or was everything bone dry?
2. These leaks usually start higher and they go to the lowest point possible so trace as high as possible and see where the highest place is.
3. If you overfilled the tranny, by logic the extra fluid in the system tends to escape or go somewhere, forcing it's way out at the weakest point possible. So check again if you put in more than what you drain.
4. When you drove last, did it do ok, or did you feel something different?

Hope you get it all resolved. Everything has a fix.

 

Funny story, the seal does look fragile. Something I definitely recognized before I slid the transfer case back onto the transmission output shaft. I needed to be extra careful since I did not replace it with a new one.

And wouldn’t you know it, I totally bungled that part of the job. I installed the transfer case with me on my back, slid the transfer shaft in, and missed the transmission output shaft on my first couple of attempts. The transfer shaft ended up resting directly on that seal on every time I missed. Sigh lol. You should have heard how far my french has come!

Anywho, I wanted to finish the job so I figured I’d chance it and keep an eye on it for leaks. It’s been 35,000 miles since I finished the job, and so far no leaks. Also, the salvage transfer case I used did not have the cleanest looking surface where the seal rides (fine surface rust). I tried to gently clean it as best I could.

All this to say, I definitely feel I’m on borrowed time with this seal.

ETA: I thought you’d appreciate this pic, 2toys…this shows a ring on the salvage TC shaft showing where at least one part of the seal makes contact.

 

I have reused installed lip seals a number of times. I have had both good and bad luck doing so. As a note: never touch the seal lip with your fingers. In this case - use a soft artist style paint brush to wet the lip area of the seal, as well as the shaft that will be inserted into the seal. It goes without saying that cleanliness matters.

I don't think you are on borrowed time with the reused seal. Since it didn't leak when you reassembled the TC to the transmission it might surprise you how long it will last - as long as the transmission fluid doesn't get low.

The ring on the transfer case shaft is common. It is the reason the lip needs to be wet as well as the shaft that it rides on. Depending on rotation speed of the shaft when it is working, the lip can be burned if the lip is dry and not wetted during assembly, which obviously would leak. it's amazing how a soft seal can leave a mark in hardened chromed surfaces that are ground to size.

Congrats on your mastery of the French language!

 

Hey Chessguy, here are the answers to your questions:

1. when you started the job was the unit showing the same leaks? Or was everything bone dry? Didnt check, plus leak is a bit further down from fluid pan and refill are
2. These leaks usually start higher and they go to the lowest point possible so trace as high as possible and see where the highest place is. Couldnt see it higher, but upon looking the bottom of the transmission looks "wet"
3. If you overfilled the tranny, by logic the extra fluid in the system tends to escape or go somewhere, forcing it's way out at the weakest point possible. So check again if you put in more than what you drain. Will do
4. When you drove last, did it do ok, or did you feel something different? Nope, drives exactly as normal, took it up and down a steep high, changed gears right about when it normally does.

i brought the truck new and do all my own maintenance. I did notice when i first did the drain and refill i got one quart less out of it. I refilled the same amount plus a little extra but found when i went to do the level check i had no fluid. So i put in an extra quart and then did the level check. I read on various online posts others had the same. First time round i did pull the level check at 101F and not the 104F, which more people are saying is correct. Maybe that caused an overfill?

 

Checked this morning, no leaks on the garage floor.

 

first you need to establish exactly where the leak is coming from. Do the brake clean on it and watch.

 

When I did my pan drain/refill, I had the same experience. I had to add a fair bit more fluid than drained in order to get a dribble from the standpipe.

Checking the temp at 101 vs 104 probably wont make any difference *if* the temperature specs are there to account for changing volume as temp increases. I’ve seen videos of people checking fluid volume at different temperature, and it hardly seemed to change at all, hot or cold.

But if the temp specs for checking the standpipe are there because, for example…a certain valve opens in that temp range, that leads to some sort of circulation and change in level…then I guess one degree of difference might actually be very critical.

Because I don’t know the exact reason engineers gave us those temp specs, I prefer to take the pan-temp reading as reported through OBD-II (Car Scanner app is my favorite). Using a IR temp gun would introduce too many variables that could interfere with getting the exact temp.

 

Do you have a quick synopsis of what your procedure was when you did your drain and fill?

 

In response to @ChessGuy post above. I mentioned that in my post, that the general assumption of why we are given a temp range for checking level is because fluid volume increases with temp (expansion of fluid). But at the same time, I’ve seen vids of people measuring volume of trans fluid at different temps, and they found that volume did not appreciably change between, iirc, room temp and low 100s.

This is why it begs the question…is volume expansion (as a function of temp) the real reason they give us very specific ranges for checking level? I’m just wondering out loud if maybe there’s another reason…like for examples valves and such opening or closing within the “check temp range” which lead to different levels inside the pan.

 

This is a job that requires I not be distracted, as there is an order to things, and timing is important because the temp window passes quickly once you reach it. Probably best not to rely on a quick synopsis, but to understand what you’re going to be doing before doing it, rehearse it in your mind before doing it, then executing.

But basically, if I recall:

-remove the fill plug first, as a matter of good practice.

-With the engine off and cold, I drained the pan fluid using the drain plug on the pan into a graduated container.

-Refilled trans with the same quantity of new fluid.

-Start engine, and open standpipe plug on pan. If no fluid comes out, add more until it starts overflowing, then close up standpipe drain before it gets to the “dribble” rate.

-Wait forever for the temp to rise to the check temp range. I put it in drive and held the brake to speed it up a little. And to circulate things.

-Monitor temps, once within range, open the standpipe, let drain till fast dribble, then close standpipe.


I seem to remember being surprised at having much less of a dribble at target temps than I expected, so I may have added a little more and restarted the last standpipe procedure (I’m OCD lol).

 

Thank you. I had no plans to use your summary as the instructions to perform the task, just was curious what all you did in general to see if it's something I would be willing to undertake. The procedure has been written up plenty of times, but it seems the details of how to monitor the correct temperature to do the level check differ from user to user.

 

To me, it’s one of those things that requires the right tools before doing it. I don’t want to risk a transmission on the assumption other simpler techiques are good enough. In this case, I think having a Obd-2 reader to get the pan temp is important, as well as a brand new, squeaky clean fluid pump to refill/add fluid.

 

It's easy.

Once your 4runner warms up, all you have to do is hotwire the OBDII port with a paperclip and move your shifter around like you're playing Street Fighter at the arcade!

What could go wrong?

 

I know, right?

Then there's the possibility that once you've completed the process, however successfully, your eyes (like the OP) will mysteriously be opened to see heretofore unknown leaks showing up all around your transmission.

 

The solution to that is easy. Just don’t look around!

 

As long as your paperclip isn't in the "wrong hole" to fry the ECM or BCM, not much other than burning your arm on the cats!

 

Nah, no temperature valves or transmission thermostats. What do you think you drive, Tacoma 6-speed?

In the past century where transmissions historically had dipsticks, usually there were hot and cold markings (like the PS reservoir still does) and you were told to use the hot markings for more accuracy. The low viscosity WS fluid supposedly has greater thermal expansion than legacy fluids, so Toyota introduced the electronic temp check.

The first year or so of A750 used Type IV fluid and had a dipstick:

 

So did as instructed, cleaned everything around that area with brake clean and took it for a twenty minute drive, involving various inclines / declines / acceleration / deceleration, forcing gear changes, etc.

Found the leak to be that one bolt at the bottom, images attached.

A few questions for you all please:

1) Is it worth fixing this? A friend of mine called it seepage rather than a leak.
2) I had scheduled a road trip, will cover about 1500 miles, is it ok to still do that?
3) Looking at the photo, its the back end of the transmission leading to the TC, can anyone confirm what this bolt is attached to?
4) Should i even have it repaired, worried about the repair shop doing more damage than good, hence why i started doing all my own maintenance in the first place.
5) Any 5th gen transmission leaks are unheard of, did i cause this by missing something?
6) My plan of action was to monitor the leak and in a couple of years do a top up on fluid and level check. Then a couple of years after that it should be due for a drain and fill again. Thoughts / risks / concerns?

I appreciate all the responses.

Thanks,

 

Is that bolt torqued to spec ?

 

At first I was thinking, yeah, just tighten it a smidge to see if the leak goes away…but the problem is that the bolt is not the source of the leak. The leak is on the seal that goes around the transfer case input shaft. The trans fluid the just leaks into the hollow space and accumulates until it makes it way out through the machined surfaces between the transfer case and the adapter case mounted to the transmission. It doesn’t have any gasket at that interface precisely because it’s supposed to be a dry cavity.

My opinions in response to your questions:

1. It’s worth watching it a while before deciding what to do. If it stays a slow seep, maybe I would just leave it until it’s convenient to fix. But, if you’re physically able, this job might fall under a DIY category. Even if you don’t have a lift.

2. I’d drive it a as much as you can before the trip in order to establish how much it’s leaking.

3. That bolt, and all other similar bolts around the curcumference of that case, is simply what joins the transfer case to the case adapter that’s connected to the transmission
If you take them all out, and slide the transfer case backwards to remove it, this is what’s left. You can see the receiving end of those bolt holes in this pic.


4. I wouldn’t worry about having it repaired if it’s necessary. It’s not a super complicated job (it’s not like splitting the cases on the transfer case and exposing all its innards). Yes, everything can be screwed up, but this seems to be a low risk job for some one that works carefully. Like I said, it may be within reach of a DIY job, so long as you’re careful about how you slide the transfer case back on so you don’t mangle the new seal. That requires muscles and luck, or a jack for the transfer and a method to keep it well balanced and positioned while you do the lift and slide. That’s going to be the biggest pain will be neck. Next biggest pain is torquing down the driveshaft bolts with wrenches that are too short lol.

5. You didn’t cause this leak. Unless maybe if you’ve already needed to remove and reinstall the transfer case previously.

6. That’s a reasonable plan I think…but only after you’ve established the leak rate. If you start seeing puddles or if the other bolts start to show drips, that means you have fluid collecting in that empty space. If that’s the case, I’d get it fixed.

 

You are fine.

 

Figure 20 minutes to leak 1 drop. 20 drops = 1 mL. The transmission can malfunction with 1L or 1000 mL leaked out. 20x20x1000/60/24 = 277 days before the transmission malfunctions from this leak, assuming it doesn't get worse (it might on very cold or very hot days).

For what it's worth, check the transmission breather isn't clogged. The transmission and transfer case breathers are between the back of the engine and the firewall: