Geatbox rising oil leve (1 Viewer)

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Joined
May 26, 2022
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Location
Texas
Hi guys,
I'm new to this forum. Searched before posting this thread, but did not found such issue.
So, I'm owner since 1y and half of LX450 and when I get the car the oil in gearbox was far above maximum level on cold measurement and hot.
Then 2-3 moths and ~1000 miles I serviced the car. Change all fluids, repair a lot of stuffs and also changed the oil in gearbox with filter. Also the gearbox was removed from the car and sealing was changed.
Car started shifting very smooth...
From time to time I was checking the oil levels, and oil started to raise.
Checked the coolant, no change in level, the oil in gearbox is still red and did not change the color.
Suddenly after 1500 miles gearbox started to leak a lot.
So currently car is in service again, we will remove gearbox again and we will try to find where this leak comes.
But question is why oil is rising the level, we checked transfer box oil and it's just where should be.
Is someone knows why oil is rising?
 
When you check the transmission fluid level, are you checking it while it is running or while it is not running?
 
How is your coolant level? There's a transmission cooler/warmer in the bottom of the radiator. If that corrodes sufficiently, you'll get coolant mixing with your transmission fluid. That will quickly destroy a transmission.
 
When you check the transmission fluid level, are you checking it while it is running or while it is not running?
I always check the level when engine is running. Once on cold gearbox and then when I back after driving at least 30~40 miles.


How is your coolant level? There's a transmission cooler/warmer in the bottom of the radiator. If that corrodes sufficiently, you'll get coolant mixing with your transmission fluid. That will quickly destroy a transmission.
Coolant is not changing the level. And also the oil in gearbox is still clear and like new.
 
If the "gear box" is the automatic transmission. Then I would change the filter in the pan. It may be clogged with friction material. Drop the pan, clean the magnets, install a new filter.

The auto trans in the LX450 takes 15-16 quarts I think (I just know its alot). If only the pan was drained using the drain plug, you only get about 6 quart from the pan. It sounds like just enough trans oil is getting through the filter, The oil is pumped out to the oil cooler and then goes back to the pan faster than the trans pump can pull the fluid.

Or.....the seal between the transfer case and the transmission is leaking and gear oil is getting into the transmission....

My guess. I dirty pan filter. Or the new filter was installed incorrectly.
 
If the "gear box" is the automatic transmission. Then I would change the filter in the pan. It may be clogged with friction material. Drop the pan, clean the magnets, install a new filter.

The auto trans in the LX450 takes 15-16 quarts I think (I just know its alot). If only the pan was drained using the drain plug, you only get about 6 quart from the pan. It sounds like just enough trans oil is getting through the filter, The oil is pumped out to the oil cooler and then goes back to the pan faster than the trans pump can pull the fluid.

Or.....the seal between the transfer case and the transmission is leaking and gear oil is getting into the transmission....

My guess. I dirty pan filter. Or the new filter was installed incorrectly.
The filter is new and the pan was removed before ~1000 mils
One of our guesses was seal between transfer case, but the level in transfer case is up to maximum since it was changed also before 1000 mils.
We still did not removed the gearbox to check what is it, but it's leaking even on not running engine
I'll share more info when I have, but most probably hydro pump seal or the seal inside the transfer case is leaking
 
Ok,
I'll try not to shotgun a bunch of what-ifs...
How many miles on the transmission? In general was the rig maintained? Or are you fixing/bringing the rig back to life?
The inner T-case seal is a possibility, however not likely. This would mean bearings or shims in the trans or t-case have worn enough to allow enough movement to release gear oil past the seal into the transmission. Usually its trans fluid into the t-case.

How dirty was the pan during the first oil change?
As you know, transmissions do not make fluid. Was the transmission overfilled? only half of the total fill comes out via the drain plug (less than half).
It is possible, changing the fluid released additional (loose) friction material into the wetted path that remained inside the transmission. It may be the transmission fluid needs to be changed again. Drop the pan, and inspect the filter. Shine a light through, can you see light when looking from the other side?
in addition to the pan filter Install a Magnefine fluid filter on the cooler return line.

Magnefine Inline Transmission Power Steering Filters

https://www.magnefinefilters.com

One way to ensure a full flush is to drop the pan, change the filter, add new fluid (topoff). Disconnect the return hose from the transmission cooler. Attach a piece of hose to the oil cooler and put the other end into a large bucket. Using the dry fill (transmission) oil amount. Subtract the fluid that was drained from the pan. Start the rig with the drain hose in the bucket. The transmission oil pump will start pumping the internal (transmission fluid) into the bucket. Stop when you see clean red fluid or the amount of fluid equals a total fill (pan + bucket). This process can be messy. Have a person ready to stop the engine if the flow stops, or never starts. This will not hurt the transmission/torque converter. Provided you turn the engine off as soon as the fluid stops pumping or you have reached the total fill amount.

I am leaning toward needing a second flush.

 
Copied from the truth portal (google):
When you have old or burnt transmission fluid, it may become discolored and cause varnish deposits to build up inside the system. These deposits typically float around the old fluid and don’t really build up anywhere as you continue using the same fluid.
However, once you change the old fluid with new fluid, these deposits get washed away and it becomes sludge that sticks to the filters of your transmission system. This prevents transmission fluid from flowing through the transmission.
Therefore, you need to flush your transmission before adding new fluid.
 
Any update?
 
"---also changed the oil in gearbox with filter. Also the gearbox was removed from the car and sealing was changed.

Questions:

Why was the transmission removed from the vehicle??

What seals were changed??

Where is the leak coming from: the pan, the front of bellhousing, rear near transfer case, the side of the transmission, or???
 
"---also changed the oil in gearbox with filter. Also the gearbox was removed from the car and sealing was changed.

Questions:

Why was the transmission removed from the vehicle??

What seals were changed??

Where is the leak coming from: the pan, the front of bellhousing, rear near transfer case, the side of the transmission, or???
I'll try to summarize from the begging.
I bought my LX450 from Florida, before dealer send me the car, he made maintenence which was removing the gearbox to change the sealing on engine side because he explained to me it was leaking.
So he did it. I received the car and it was not leaking.
However I wanted to make full revision on car status and I went to a service which know what is doing and did serviced a lot of 80 series. The mechanic found that a lot of bolts were not tighten on gearbox and also he saw that dealer service used some silicone on the side of gearbox. Mechanic saw this from the service opening door on gearbox side, so we decided to remove the gear from car and to check why silicone was used and also to change the sealing on gearbox side.
I forgot to mention that when I received the car, oil in gearbox was above high level.
Maintenance my mechanic included changing the oil on gearbox, a new filter and properly leveled oil.
When I get the car it was great and was shifting very well, shifting was smooth.
But the level started rising after ~500 miles. Then suddenly one day when I parked the car on rear and stopped the engine for about 2-3 hours, I saw a small leak on floor the car was ~6-700 miles after maintenence.
I started checking every time when I park for a leak and there was nothing, absolutely nothing for next 600 mes. Non a single drop, not in my garage, not on every place I parked. But oil level in gearbox was rising slowly every day.
Couplenof weeks passad and ~ 5-600miles without leaking.
Then I parked the car again on same place and again on rear. Guess what another leaking and it was more than before. And after this day leaking did not stopped.
My car is in same service where my mechanic did all maintenance, but still no time to remove the gearbox and check for visible signs.
So this is the story, 2 main question still in my head
Why level continue rising and where could be the leaking from.
Oil did not change the color, so broken radiator not seems to be a reason for rising level and also transfer case is not loosing oil, we did checked this.
Something that mechanic told me last week was that leaking now continue even if car is sitting on place and engine is not running.
 
Have you even tried to get the dealer in Florida to take responsibility for this?
Too late :( it's been around 1y and half, since I bought it.
Im in Europe :)

To answer the question where is leaking, it from inside the bell. And the fluid is on the bottom edge of the bell comming from the small hole just beneath the service door on the gearbox.
Will try to upload some pictures if you want details later.
 
So it sounds like they did a botch job on your rear main seal and it's still messed up. The transmission has to come off to fix that, no way around it. BUT there is no way that this issue could inject oil into your transmission.

I suspect the real issue is your rear main is leaking and you and your mechanic are quick to jump to conclusions that there are other issues at play. Could there be? Possibly, but unlikely. Transmissions don't just create fluid over time and there is no path between the engine and transmission that will squirt oil into the trans.

What color is the oil that is leaking onto the ground? is it red trans fluid or brown oil?

How are you determining if it's overfilled? Dipstick? If so are you following the FSM's guidelines on how to correctly check it? (engine on, up to normal operating temp, shifter in neutral, level ground). Measuring the level at different temperatures will result in very different readings, additionally, if the mechanic filled the transmission to the full mark on the dipstick it will read as overfilled once warm. There is a procedure and a propper way to fill the trans in the FSM. You can get your own FREE version of TOYOTA's Factory Service Manual in the link in my signature.
 
Added to above: if the leak is brown (engine oil) and dripping off the front bottom of the bellhousing it could be engine oil. So your mechanic should also consider that the rear arch area of the upper engine oil pan could be the source of the leak.

Or to put it another way: the rear arch of the upper engine oil pan is directly below the rear main crank seal. So if either is leaking the engine oil will drip out from the same location (bottom front of the bellhousing).

Another possible sourse of a transmission fluid leak is from the power steering system, that is assuming the Power steering system is filled with transmission fluid. A leak from that system can be blown backwards along the side of the engine and drip off the side or rear of the engine or the bellhousing.

Your mechanic could use a UV dye one system at a time (engine oil, transmission, power steering) to help determine where the leak is coming from.

If you're concerned that your transmission fluid has become contaminated
(causing the level to increase) you could send a sample of used transmission fluid to a company that performs Oil Analysis (engine oil, transmission fluid, etc).
 
One other consideration- the transfer case should have gear oil in it, it does not use transmission fluid, so if your transmission fluid is bright red and doesn't look contaminated, it's not rising due to a leak between the transmission and transfer case (unless you do have transmission fluid in the transfer case, in which case you should rectify that immediately). Not to mention that it would be difficult for fluid to transfer between the two, but maybe not impossible. I can't remember if the breathers are connected. In any case, you can check the oil level in the transfer case.

I'd agree that the rising transmission fluid level is likely due to misreading the dipstick. Get the leak fixed, and make sure they use OEM seals, sealant, etc.
 
Once years ago when I had my 80 serviced at a dealership they put automatic transmission fluid (ATF) into the transfer case instead of gear oil, so another reason to check the fluid in the transfer case.
 
The oil is red and is comming from from the tiny hole. It's a lot more now since these pictures are a bit old, they are from the begging when I saw first sign of continuous leaking.
Level up for sure it's not from transfer case, this we already confirm it.
I hope soon we get it down and visually check and found it.

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So the theory is that the transmission is leaking fluid, but the fluid level in the transmission is going up??
 
there is no way the fluid level is going up. It's likely being miss-measured, was probably overfilled and there is a leak. These transmissions really don't like being overfilled, it can cause foaming, increased and inconsistent line pressure and stress on the seals.
 

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