Leaking ATF at transmission/transfer case

[ferioking]

Hello,

I have an imported 1998 Toyota Landcruiser 100 series with the 4.2 diesel with the A442F transmission. Just recently got back from a 3,500 mile round trip from Texas to New Jersey. I went to back out the 100 series out the garage to give it an wash and noticed a small amount of ATF on the ground. During my trip I didn’t have any weird shifts or symptoms.

I crawled underneath the 100 series and tracked the ATF leaking from rear of transmission where it meets the transfers case.

Checked ATF level and it reads full on “hot” side of dipstick with vehicle cold. The ATF was reading full on “cold” side with vehicle cold a month ago after performing a drain and fill.

I checked around the transfer case and transmission with no other leaks. Transmission cooler lines were leak free. Dipstick out of transmission was also leak free.

Can anyone give me any input on possible fix? Thank you in advance.

 

[ferioking]

Dipstick level when vehicle is cold shows full on “hot”

 

[3_puppies]

might be the rear seal on the trans?
the transfer and trans do not share oil and they use different fluids

 

[BullElk]

AT-205 Reseal

 

[CrackedManifold]

^^^^ AT-205

Works wonders for a leaking steering rack.

 

[2001LC]

First check A/T Fluid level, after driving to warm up (~160F) and shifting through all gear. While parked on level ground, engine idling, A/T in P or N. Check level by first pulling and wiping dip stick, then reinsert "fully" and pull out to read within ~3 seconds.

Clogged breather?
Remove long breather hose, from end at Y (back of A/T, TC adapter case). Let hose hang down for 6 to 8 hours (best in warmest time of day), into a catch can. See if any fluid come out. Of course you can remove long hose from both ends, to clear on the bench. But we'd like to know if any fluid in it, which could be clogging it. Next test your breather to make sure functioning properly. I use my HP air, but one can simple blow into hose. Air should pass easily, through hose out breather.

Knowing if breather or its hose clogged, is a valuable clue. If so, as fluid in Transfer case and A/T expands and foams. The foams can pass from one to the other via Y (98-02), that connect TC & A/T to the one breather.

Flush transfer case. I fill with fresh Mobil 1 75w-90 @ ~30K after draining (dripping) for >1 hour at >68f. To set TC level: Parked on level ground. You may want to add measured amount of AT-205 at this point (optionable). Fill w/M1 75w-90, until flows out, fill hole. Let set/rest 15 mins (@ 68F) or drive to warm, then then top, until flow out fill hole. Place new gasket on fill plug, as you did on drain plug. Torque to 27ft-lbf.

Flush A/T. In 98-02, I use 12 qt. Mobil 1 Multi Vehicle Full synthetic.

Clean all oils from A/T & TC. Clean again again after a few months and few thousand of miles. Monitor for leak. We can live with very minor leak. But requiers check levels as frequent as leak dictates.

If leak issue of A/T - TC clogged breather and or over filling and or mixing of fluids. Above, may be all that is needed. If on the other hand, leak persist. Determine which fluid leak is. Likely gear lube. Reseal TC case.

 

[ferioking]

First check A/T Fluid level, after driving to warm up (~160F) and shifting through all gear. While parked on level ground, engine idling, A/T in P or N. Check level by first pulling and wiping dip stick, then reinsert "fully" and pull out to read within ~3 seconds.

Clogged breather?
Remove long breather hose, from end at Y (back of A/T, TC adapter case). Let hose hang down for 6 to 8 hours (best in warmest time of day), into a catch can. See if any fluid come out. Of course you can remove long hose from both ends, to clear on the bench. But we'd like to know if any fluid in it, which could be clogging it. Next test your breather to make sure functioning properly. I use my HP air, but one can simple blow into hose. Air should pass easily, through hose out breather.

Knowing if breather or its hose clogged, is a valuable clue. If so, as fluid in Transfer case and A/T expands and foams. The foams can pass from one to the other via Y (98-02), that connect TC & A/T to the one breather.

Flush transfer case. I fill with fresh Mobil 1 75w-90 @ ~30K after draining (dripping) for >1 hour at >68f. To set TC level: Parked on level ground. You may want to add measured amount of AT-205 at this point (optionable). Fill w/M1 75w-90, until flows out, fill hole. Let set/rest 15 mins (@ 68F) or drive to warm, then then top, until flow out fill hole. Place new gasket on fill plug, as you did on drain plug. Torque to 27ft-lbf.

Flush A/T. In 98-02, I use 12 qt. Mobil 1 Multi Vehicle Full synthetic.

Clean all oils from A/T & TC. Clean again again after a few months and few thousand of miles. Monitor for leak. We can live with very minor leak. But requiers check levels as frequent as leak dictates.

If leak issue of A/T - TC clogged breather and or over filling and or mixing of fluids. Above, may be all that is needed. If on the other hand, leak persist. Determine which fluid leak is. Likely gear lube. Reseal TC case.

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Checked ATF fluid as stated and reads low so I’m losing ATF fluid. I checked TC and it’s only gear oil in there. Will have to check breather hoses to figure out if they’re clogged.

 

[ferioking]

Is “transfer breather B” on picture what your referring to check if clogged?

 

[2001LC]

The long hose that travels to engine.

 

[Lockmitre]

Reviving this thread...Did you ever solve this issue? I have the same ATF leak where the Trans meets the Transfer Case. I also have a 1998 JDM import but with the 4.7 V8. I have only had it a week but i noticed that it looks like this leak has been there for a while. I cleaned the area to see where it was coming from but couldnt tell, went for a 30 minute drive and looked under there again and saw it coming from the same spot as OP. New to owning a 100 series so any help is appreciated.

 

[Malleus]

Assuming your breather valve/hose isn't blocked, it's the rear case seal.

 

[Lockmitre]

Is the idea that the breather gets blocked and causes pressure to build in the trans forcing fluid out of the seals? I checked the trans dipstick and it is reading really low, at temp its reading in the cold section of the dipstick....

Assuming your breather valve/hose isn't blocked, it's the rear case seal.

 

[ferioking]

Reviving this thread...Did you ever solve this issue? I have the same ATF leak where the Trans meets the Transfer Case. I also have a 1998 JDM import but with the 4.7 V8. I have only had it a week but i noticed that it looks like this leak has been there for a while. I cleaned the area to see where it was coming from but couldnt tell, went for a 30 minute drive and looked under there again and saw it coming from the same spot as OP. New to owning a 100 series so any help is appreciated.

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Yes sir, it ended up being the seal between trans and transfer case. I replaced both on trans side and transfer case side. Stopped the leak.

Just drop transfer case to get to both seals.

 

[Lockmitre]

Yes sir, it ended up being the seal between trans and transfer case. I replaced both on trans side and transfer case side. Stopped the leak.

Just drop transfer case to get to both seals.

Copy....Unfortunate I guess. Not unexpected though with a 28 year old vehicle. I appreciate the response!

 

[Malleus]

The extension housing is supposed to be dry. The ATF is supposed to be in the transmission and the gear oil is supposed to be in the transfer case. The extension housing seal isn't there to keep ATF from leaking; the rear transmission case seal is supposed to do that.

Yes, the breather is supposed to prevent overpressure in the case, but if your seal leaks because of that overpressure condition, simply removing the blockage won't solve the problem. The seal has already been compromised and it will continue to leak, even if the breather functions properly.

 

[Lockmitre]

The extension housing is supposed to be dry. The ATF is supposed to be in the transmission and the gear oil is supposed to be in the transfer case. The extension housing seal isn't there to keep ATF from leaking; the rear transmission case seal is supposed to do that.

Yes, the breather is supposed to prevent overpressure in the case, but if your seal leaks because of that overpressure condition, simply removing the blockage won't solve the problem. The seal has already been compromised and it will continue to leak, even if the breather functions properly.

Im assuming if i replace the seal, which im going to, If i dont also check/clear the breather hose it will just leak again? Both will need to be remedied?

 

[Malleus]

Again, replacing the seal in the extension housing will only mask your problem. The seal that's leaking is the rear transmission case seal. FWIW, getting that seal out is only half the problem. The tailshaft protrudes nearly a foot from the rear case face where the seal is. You'll need a very, very long seal installer to get it in properly.

You can do this with the transmission installed, but you absolutely have to remove the transfer case to do it. If it was me, I'd pull both; getting the transfer case off the transmission is a PITA and it's nowhere near as much trouble as getting it back on, under the truck. With both off the truck, it's a piece of cake. The bonus is you get to clean the engine–transmission harness joins while you're at it. You'll need to climb over the top of the engine to get at them; they're hiding under the lower edge of the firewall.

And yes, the breather still need to work properly.

 

[Lockmitre]

FWIW, The Lexus dealership quoted me 1300 to replace the transmission and transfer case seals. Not as much as I was expecting considering they told me they need to drop the transfer case to get to both just as stated previously in the earlier posts. I would do it myself but I currently lack the tools and space needed for this type of repair. Ill bite the bullet and have the dealer do it this time. I would think I can check the breather hose myself easy enough when i get the truck back.

 

[ferioking]

FWIW, The Lexus dealership quoted me 1300 to replace the transmission and transfer case seals. Not as much as I was expecting considering they told me they need to drop the transfer case to get to both just as stated previously in the earlier posts. I would do it myself but I currently lack the tools and space needed for this type of repair. Ill bite the bullet and have the dealer do it this time. I would think I can check the breather hose myself easy enough when i get the truck back.

I replaced mine inside my garage with a transmission jack ALONE with no lift. Pulled the transfer case off replaced seal on my garage floor and replaced the trans rear seal without having to remove the transmission.

I also did check my breather hose for blockage while having the TC off.

I drained the TC just to make sure the ATF didn’t make its way in there which it didn’t but cheap insurance.

I’ve driven the rig cross country with no further leaks and adequate trans fluid.

 

[Malleus]

FWIW, The Lexus dealership quoted me 1300 to replace the transmission and transfer case seals. Not as much as I was expecting considering they told me they need to drop the transfer case to get to both just as stated previously in the earlier posts. I would do it myself but I currently lack the tools and space needed for this type of repair. Ill bite the bullet and have the dealer do it this time. I would think I can check the breather hose myself easy enough when i get the truck back.

Have them do it when the pull the transfer case. You're already paying them to mitigate the pain, why not be pain free?