Help - Disappearing Auto Transmission Fluid

Hi Guys. I've got a 2010, 4.0 Liter, V6, access cab, 4x4, TRD Off Road with 117,000 miles on it that has started mysteriously losing quarts of automatic transmission fluid. The problem first started with two rough shifts back at 100,000 miles. Toyota dealership looked at my transmission and said they couldn't find anything wrong.

Then at about 110,000 I developed a rough shifting problem and the truck would sometimes get stuck at third gear and wouldn't shift into 4th. Took it to a specialty transmission shop and they said I was 2.5 quarts low on fluid, but they couldn't find a leak anywhere. They had it for four days and couldn't figure it out.

Then about 5 months later (about 116,000) I noticed the rough shifting problem starting to come back. Took it back to the same transmission shop and they said it was 3 quarts low, and after another four days...they still can't find the leak!

In all this time I've never seen so much as a drop of transmission fluid on my indoor cement garage floor. It's back to driving fine at 117,000 miles, but I really don't want to put in a new transmission or rebuild this one if I can't be sure it's going to fix the problem.

Has anyone heard of this happening? Any wild and crazy ideas?

 

This may be a little out there but check your radiator.

I have never seen a transmission run to the point where it burns transmission fluid. You likely do have a leak and may want to get it checked over by another shop.

 

Listen to this guy he us very knowledgeable.

 

Have you checked to see if there is atf in your coolant? Maybe you radiator trans cooler has broke and it going into your coolant. Pink milkshake

 

What’s the bottom of your truck look like? You said your garage floor is clear, but what about the truck?

 

It's dark outside, but I shined my spotlight on it and my coolant looks pink. It was dark and kind of difficult to tell if it looked foamy or not. I'll update tomorrow afternoon.

 

@gearcruncher

That's 5.5 quarts that went somewhere. Could be that ATF is leaking only when under pressure - when you drive; hence, it stops leaking in the garage/driveway, but there should be some evidence at/near the leak source; maybe a pinhole in a rubber line. That much oil transferring into the cooling system would have displaced the coolant level quite a bit, or cross-contaminated into the ATF fluid which would have revealed itself when the ATF level was checked, assuming it was done correctly.

 

Check the transfer case oil level. I'm thinking it's overfilled. A lot overfilled.

 

Do you have your oil changed at a quick lube place? Maybe someone pulled the transmission plug a few times by accident, saw it was red and put it back in without saying anything?

 

How do you overfill the transfer case?

 

ATF leaking from the transmission into the transfer case.

 

Another good possibility.

 

I see...I didn't know that was possible...thanks

 

5qts worth though?

 

Too many factors when you have other hands under the hood of the car but your own. Especially if you take it to a jiffy lube style place. Could be someone pulled the transmission plug thinking it was an oil pan drain plug. Or it could be that last time you serviced it someone filled the t-case instead of the tranny. At 110K miles the only factor for leakage would be something like a pin hole in rubber hosing as previously mentioned which leaks under pressure.

With that being said if you have a leak even a small one would show traces of it flying all over the undercarriage and eventually hitting the rear end. The undercarriage layout of these trucks can be very confusing to someone who is not familiar with it, so I understand things do happen.

Especially at 5 quarts worth. 2 quarts low of fluid alone would cause odd slippage issues at first gear engagement and may cause some slippage into overdrive. I understand you were not at 5 quarts low right off the bat but on two different occasions you were low. What was the mileage interval in between these findings and most importantly, did you have recent services performed to the truck. If so, what was performed?

 

That's what I was thinking, easy to rule out, just remove the fill plug, if overfilled oil will come out.

 

I would agree that Iffy Lube could have drained his trans by mistake, and the quantity of loss makes sense with what the trans pan holds. But they must have realized their mistake and dropped the engine oil and forgot to refill the trans, because if they sent him off with 11qts of oil in his motor I guess that would have caused problems. Then to have it happen twice? that's some pretty bad luck.

 

He didn't take it to a Jiffy Lube place. He said he took his truck twice to the same "specialty transmission shop".

ATF cannot leak into the transfer case. The transfer case and transmission are two separate components and they don't share hydraulic lines; and the transfer case takes gear oil. The transfer case takes 1.1 qts to replace; you can't physically add more than that on level ground.

CO should find another transmission shop.

 

In the old days there used to be a vacuum modulator on American automatic transmissions. The diaphragms were know to develop occasional leaks and the transmission fluid would be sucked into the intake manifold and burned in the engine. No leaks to be found and just a wee bit of additional engine smoke, blue by the way.
Is there a vacuum connection to the Toyota transmission? If so would be a good place to look for the source of the leak.

 

This is exactly what happened to my 1959 Chevy.......... No drips or anything... took it to a buddy mechanic... he said Modulator valve, right away....

That WAS the culprit.....!!

This was my first thought when I read this post.... I don't know if the Tacos have one, but @gearcruncher would know for sure...!!

How about you Crunch..??

John