Will transfer-case gear lube foam, if contaminated or overfill?

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Edited 11/19/22. This thread gets more into foaming of lubricates, causes and effects. The two main causes of excessive foaming, we're concerned with: Overfilling and contamination. I also came to conclusion, with helpful post from others and looking at adapter case. It would be nearly impossible in the 98-02 to get cross contamination between transmission & transfer case. As such I also change title replacing the words: "ATF" with "overfill!"
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I would think, if gear lube contaminated with ATF, it would foam. What say you mud?

Also, if ATF leaked from transmission into transfer-case. Couldn't it get in gear lube, in the 98-02? I've never pulled one apart, so don't know!

I've got and issue, in a 2001 w/353K miles. It's very clean stock Land Cruiser. With transfer-case leaking rather badly at both forward & aft output shafts. Why is the question! I've seen many, some with more miles, some never flushed, not leak. Never have I seen one leak this bad!
Possibilities:
1) Is bad bearing(s) or gears, causing vibration/wobble, damaging seal(s)? At both end, at same time. Than I'd think it to be a bad transfer case altogether. Seems fine IMO, just in town City & HWY driving.
2) Excessive fluid pressure, which over-filling could cause. Last fill was DIY, and IMO likely under-filled a tad. It was noted leaking, before last flush also.
3) Gone to long before first flush, and old gear lube damaged seal(s). Note: most rubber on vehicle about as one would think or better for age and miles.
4) Contamination in transfer-case gear lube causing excessive foaming of gear lube. Which would greatly increase pressure, and possible blow foam out breather. May explain fluid in breather tube.
5)?

Here is some current history and what I observed:

Owner, DIY changed transmission ATF and transfer-case gear lube. Just before 1,600 miles HWY drive, to me here in Denver. Owner foggy on transmission topping procedure, he used. But seem to be detail oriented and meticulous. He slow filled transfer-case and let run out fill hole, before plugging fill hole. Not letting settle for 15 minutes, than re-topping as FSM recommends. Which generally leaves, just a tad low.

I saw leaks upon inspection. Worst is transfer-case at both out-put shafts. leaving oil spots everywhere it was parked. Also some ATF residue attracting dust on plastic, at bottom of radiator near pre ATF oil cooler nipples/lines, in and out. Found the After-Market (AM) radiator pre cooler nipple's large nuts, needed snugging. Which they often do "right out of the box" in these AM radiator's. ATF cooler hose clamps, not put back in factory indentations (orientation), which can lead to weeps. It did not appear as if a lot of ATF fluid seeped out (see pictures).
Inspection notes:
A) Transfer-case, leaking badly at both ends.
B) Transmission .5 qt low, at between ~158F (ATF Temp, monitored through tech stream).
C) Transfer-case ~1/3 cup over-filled, and leaking badly. Likely under-filled a tad, last flush.:hmm:
D) ~2 table spoons of what appears to be gear lube, came out of transfer case breathe tube.:hmm:

Side note: 2 times only, out of about a dozen cold start-ups. I hear a rattle while warming up. Like CAT heat shield loose rattle. Seems to be from mid undercarriage area. Engine cover and both factory under-shielding were off. Found Heat shields and their bolts, to be in excellent condition and tight, no rattle fist pounding test). This rattle was both while idling in N, and while driving in D, until operation temp reached.


Forward output shaft
IMG_0071.JPEG

Aft transfer-case output shaft leak
IMG_0076.JPEG

IMG_1370.jpeg

IMG_1371.jpeg
 
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I'm probably not much help here but I did breeze over the Chowcares video where he pulled one to do the seal. Looks like a bit of a project, might help make sense of the setup seeing it all pulled out
>> The fluid dripping picture looks pretty dark and not very thick. Have you done a drain and fill since to see if cleaner gear lube is leaking or some kind of mix?


>>
 
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JunkCrzr89

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Also, if ATF leaked from transmission into transfer-case. Couldn't it get in gear lube, in the 98-02?
That would require multiple seals to fail, at least one at the t-case input shaft, one at the back of the transmission, and 2 (IIRC) at the adapter box.
 
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I'm probably not much help here but I did breeze over the Chowcares video where he pulled one to do the seal. Looks like a bit of a project, might help make sense of the setup seeing it all pulled out
>> The fluid dripping picture looks pretty dark and not very thick. Have you done a drain and fill since to see if cleaner gear lube is leaking or some kind of mix?


>>

Thanks for posting the video.

Fluid does looked dark, in what I captured from overfill coming from fill plug also. It seem a little to dark, since had just been changed ~60 days & ~1,600 HWY miles ago. But we've no way to now how long PO(s) had gear lube in, and it can take a few flushes to clean out old gunk from fluid not synthetic and not regulary flushed.
That would require multiple seals to fail, at least one at the t-case input shaft, one at the back of the transmission, and 2 (IIRC) at the adapter box.
Thanks. I'll get parts diagram and study those 4 seals.

Do you think ATF in gear lube. Would cause gear lube to foam?

What started my wondering if ATF got in transfer case:
1) Transfer case overfilled, when it should have been low.
2) Breather tube having about 2 tbsp of gear lube.
3) Transmission low, when it was just topped.

I can't say I've checked a transfer case breather tube, for fluid before. Have you seen it holding gear lube?
 
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JunkCrzr89

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Do you think ATF in gear lube. Would cause gear lube to foam?
It shouldn’t. I know some old timers that used to mix the two on purpose in older Chevy autoboxes, often at a 50:50 ratio. Their claim was that it improved shift smoothness.

I can't say I've checked a transfer case breather tube, for fluid before. Have you seen it holding gear lube?

What do you mean by ‘holding gear lube’? If the gear oil gets hot enough, it can expand and, if the t-case is overfilled, actually come out of the breather. I’ve never seen that happen with a t-case but I have seen it happen with differentials that folks overfilled.

My opinion is that the t-case was likely overfilled, which when at operating temp caused gear oil to enter the breather tube, and upon subsequent cooling, air was sucked back into the t-case and caused foaming.
 
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wrong gear oil will foam. depends on what was used, brand and type.
 

Bisho

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You’ll need to pull the T-case to change the output seals. When I pulled mine the transmission output shaft was seeping (~280k miles). It had a small cut and I replaced it.

IIRC I don’t think it possible for the fluids to mix, though. They are 2 separate assemblies connected by a shaft. If the transmission leaked it would go in the void between the two.

1E1BB344-7C0C-4F87-A435-25368B9AB42B.png
 
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It shouldn’t. I know some old timers that used to mix the two on purpose in older Chevy autoboxes, often at a 50:50 ratio. Their claim was that it improved shift smoothness.

I can't say I've checked a transfer case breather tube, for fluid before. Have you seen it holding gear lube?

What do you mean by ‘holding gear lube’? If the gear oil gets hot enough, it can expand and, if the t-case is overfilled, actually come out of the breather. I’ve never seen that happen with a t-case but I have seen it happen with differentials that folks overfilled.

My opinion is that the t-case was likely overfilled, which when at operating temp caused gear oil to enter the breather tube, and upon subsequent cooling, air was sucked back into the t-case and caused foaming.
By holding gear lube, I mean: It had gear lube in the hose that connect TC to it's breather valve.

I had pulled hose off TC side, at first union (splice fitting about 5" form TC air pressure bleeder port). I checked breather for free air out-bound moment, then restricted air movement inbound. It seemed okay, perhaps a lite restriction. Planning on pulling TC the next morning. I just let the hose hang to floor, free from TC side port. The next morning, I found a puddle on shop floor, under open end of breather hose, hanging still attached to breather valve.

Typically I'm just checking function of breather, so just reattach hose once checked. This was first time I recall, just letting a breather hose/line hang free overnight.

So this is the question, was TC overfilled! Also was AT under filled. Was fluid in breather TC hose, just accumulation of oil droplets vapor from TC over time!

wrong gear oil will foam. depends on what was used, brand and type.
I have to agree, gear oil does foam. I saw a demo years ago, about adding lube additives in gear lube. It showed how some can cause excessive foam and reduce lubricating ability.

Doing some google searching. I find info, that all gear lubes foam. That anti foaming additive is in gear lube and ATF. The ratios varies by manufacture in PPM and type. Which are sensitive as to both. I was also seeing ATF use less PPM, than gear lube.

You’ll need to pull the T-case to change the output seals. When I pulled mine the transmission output shaft was seeping (~280k miles). It had a small cut and I replaced it.

IIRC I don’t think it possible for the fluids to mix, though. They are 2 separate assemblies connected by a shaft. If the transmission leaked it would go in the void between the two.

View attachment 3170457
Helpful picture, of the 98-02 configuration. Thanks.

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Thanks guys, some very useful info and opinions.

The owners description of how he fill TC. Leads me to believe he did not overfill. Same for transmission, in that he did not under fill. But unless I do the services, I don't know. If he was not level as he though he was, and or AT temp not correct. He'd have both levels wrong.

So I've decided to just refill TC, top AT and watch. I suspect we'll find transmission holding level. Also TC leaks and level drops. Also that breather tube does not fill with gear lube. In this event. A TC reseal with bearings should be all needed.

But if we get a repeat of AT fluid dropping and TC fluid overfill. Than we'll need to address transmission and it's root cause(s) also.

I may add AT-205 to one or both. Still considering! As this would skew the test.
 
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Bisho

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AT-205 stopped by output shaft leak for 18 months.
 

AimCOtaco

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I'd also vote for overfill or improper fill of the T-case.

I've had leaks start on long trips before to... I assume from weak parts under full heat soak running for hours impacts tolerances and moves gunks and junks about.
 

JunkCrzr89

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Any idea what brand and type of gear oil owner put in?
 
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Any idea what brand and type of gear oil owner put in?
No. I'll ask!
DIY owner in question here, and appreciate the time and suggestions on my behalf!
What did you use?

I'd also vote for overfill or improper fill of the T-case.

I've had leaks start on long trips before to... I assume from weak parts under full heat soak running for hours impacts tolerances and moves gunks and junks about.

Yeah, the more I looked at the more I am 99.99% certain, it was overfilled. Still I'm questioning the fluid found in breather hose. Was the fluid a buildup over time, or a recent event. I'll be checking more of the breather hoses in the future, not just whether breather working.

Where it is certainly possible for the seals to fail. The adapter's void, would need to fill with fluid. Since adapter case is not sealed to transfer case, it would seep out before getting to a level high enough. So unless a fluke perfect seal. I'd see a bad leak at seam of adapter case. I do see weeps at adapter seam, often. But to date, they've all been minor.

For now I cleared hose, changed gear lube to M1 75W-90 and added 2 oz. of AT-205 to transfer case.

I know some say do not use synthetic gear lube. But one gear box specialty shop, which was noted as saying that in mud. Listed Mobil 1 as the exception.

Here's this 2001.
IMG_1633.JPEG
IMG_1630.JPEG


Here's a picture of a gear lube leak at adapter in a 2006. Area was cleaned and gear lube reappeared soon after. We used AT-205 and it stopped returning.
Transfer 11-1-19 leak pinpoint.jpg
 
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AT-205 stopped by output shaft leak for 18 months.
18 months is helpful.

The question was concerning foaming. Now that I'm looking closer at "foaming". I became concerned, as I added the AT-205. Could it increase foaming. OH s*%t!

Speaking with AT-205 years ago. They said, we can just leave in or flush out, it made no difference after 5 hour use time. The seals absorbed what they needed, and would not need again for 7 to 10 years. But if foaming increased, heat would also, and so would vapor.

How can we test AT-205 effect?

Any idea what brand and type of gear oil owner put in?
You did indeed and with example. THX!

Here some info I found:
There are several ways that foam causes problems:
  1. Heat — Foam heats to extreme temperatures under pressure, generating steam within the fluid. Then, foam compounds the issue by creating an insulating layer that prevents the heat from dissipating. Heat and water contamination limit the lubricant’s effectiveness.
  2. Wear — Because air is trapped inside the fluid, the fluid barrier is no longer impenetrable and wear-causing metal-to-metal contact can occur.
  3. Oxidation — The air trapped in foam promotes oxidation and shortens the service life of the fluid.
Hydraulic and other industrial applications face another issue. When hydraulic fluids foam, they become compressible and can make machinery inoperable or extremely inefficient. The


What Causes Foaming Hydraulic Oil​

According to Causes and Solutions for Foaming in Oil, there are several possibilities as to why your hydraulic fluid is foaming. They include:

  • Contamination in the form of either water, solids, or even grease
  • Cross-contamination with the wrong type of fluid
  • Excessive aeration of the hydraulic fluid (which is usually a mechanical issue)
  • A reduction in pump output efficiency
If you've already been using defoamant, foam can still form if you are using too much or if it has depleted



 

Bisho

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I was just thinking - the breather tubes route to the dipstick / filler tube. Its conceivable that some ATF could get into the breather tubes from filling the transmission.
 

dubdub20003

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I filled with non synthetic 75w90 or whatever weight is listed on the FAQ sticky. I knew you may be into it, so didn’t spring for the good stuff… only wanted it clean before a 1600 mile trip.

I just don’t know how I could over fill in largely flat ground!
 
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Non synthetic is fine.

Perhaps PO used a poor lube, was contaminated, overfilled or combination. Which resulted in increase foaming, so it leak when you purchased. Then you quickly drain leaving enough residue of old lube, contaminating your new. Perhaps where you did the change, was not as level as you thought.

I found a series of video's "Lubrication Explained". Where Guy runs and online training courses. Here's a question on foaming, where possible cause was stated: "residue of previous product"

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1 year ago
I worked In a lubricant manufacturing industry and at times meeting foaming characterisitcs in manufacturing blends can be of challenge, any idea what could caused the failures? We are talking about brand new blending products that fails foaming specifications even after adding antifoam to the maximum level allowed.
2 replies

Lubrication Explained
1 year ago
Could be a few reasons, but usually foaming is a result of contamination. In a manufacturing plant if the same equipment is used to manufacture different products then there’s easily going to be residue of a previous product run - sometimes the additives just don’t play nicely together.

1 year ago
Thanks for responding, whish you could come and work for us:)
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I found a video, "Flender foam test". Be nice to have this equipment test.



I've never looked into issues of lubricants foaming before. I now see overfilling can increase foaming. Foaming increases pressure within a case. I've seen specific references to excessive foaming resulting in leaks and filling breather tubes. Which most notable causes of foaming, noted in a white paper "Hints & practice"of the Flender foam test equipment as well as many places. Overfilling and contamination. Overfilling needs no explanation. Contamination, can be most anything form moisture to other lubricates mixed in, to even some residue remaining when new added.

A take-way form this:

In base-line or when any service done. We need let case drain well, and care we do not overfill. We'd also be well serviced to re-flushes with the same brand lubricant a second time, in short order! So as to remove any contaminants, that may have been in or added.
 

jLB

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Same guy, or similar problem?

 
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Same guy, or similar problem?


Well that's interesting. Thanks for posting.

He said red AT oil, in breather tube. Interesting! I did not get a good look at my fluid on floor, but though it gear lube.
I need to go back and look at routing of both transmission & breather tubes.

He said red fluid from TC. But did not say, which gear lube he used or it's color. But all I've seen start life as a lite golden, turn black. He just mentioned, the type of bag lube came in. He's seems to (now) be thinking, AT fluid came from breather into TC.

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I ending-up not resealing, as I indicated would be the case. I just drained breather hose. Then drained & filled TC with M1 and some AT-205. I just top the transmission at ~160f w/M1 (which I'm told, is what was in it). In just short drives city & HWY. No leaks! But only ~100 miles total in short trips. It's being driven 1,600 later this week. So we'll see how it!.



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Side note: on seals I found a variation in seal PN #. If build date before, during or after April 2001. Old seal has ending date of use and new seal start date, both April 2001. If your MFD is 04/01 (April 2001) build date. Toyota states use old PN, which is corrected 7 of 10 times.
 

jLB

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Well that's interesting. Thanks for posting.

He said red AT oil, in breather tube. Interesting! I did not get a good look at my fluid on floor, but though it gear lube.
I need to go back and look at routing of both transmission & breather tubes.

He said red fluid from TC. But did not say, which gear lube he used or it's color. But all I've seen start life as a lite golden, turn black. He just mentioned, the type of bag lube came in. He's seems to (now) be thinking, AT fluid came from breather into TC.

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I ending-up not resealing, as I indicated would be the case. I just drained breather hose. Then drained & filled TC with M1 and some AT-205. I just top the transmission at ~160f w/M1 (which I'm told, is what was in it). In just short drives city & HWY. No leaks! But only ~100 miles total in short trips. It's being driven 1,600 later this week. So we'll see how it!.



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Side note: on seals I found a variation in seal PN #. If build date before, during or after April 2001. Old seal has ending date of use and new seal start date, both April 2001. If your MFD is 04/01 (April 2001) build date. Toyota states use old PN, which is corrected 7 of 10 times.
From what I gathered, his conclusion was that overheating the transmission fluid, while he was playing on the beaches in Baja California, was what originally caused ATF to be transferred from his transmission to his transfer case, via his breather lines. He didn’t seem to have conclusive answers of whether the AT was overfilled, but seemed to have evidence of ATF in the transfer case, leaks from the transfer case seals, and unexplained underfill to overfill in his transfer case, on the drive home.

It just seemed that it might be relevant to the problem that you were chasing.

It might be an argument for separating the AT & TC breathers, if/when you choose to extend them.
 

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