2002 Toyota Highlander_Transmission Fluid Leak

josiah

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#1
Make
Toyota
Model
Highlander
Year
2002
Miles
160000
Engine
3.0 v6
My 2002 Toyota Highlander is leaking transmission fluid. V6, 3.0 engine, appx 160,000 miles.
Key points:
1) First noticed transmission fluid on garage floor 11/28. Appx 6 inches across.
2) When my wife arrived home with the vehicle I checked the transmission fluid level with dip stick and it appeared normal (between the cold mark and the hot mark, but closer to the hot mark).
3) I looked underneath and saw fluid drops hanging from the two 10mm bolts at bottom of transaxle. because it's the lowest point.
4) Checked my Haynes manual and it suggested that common areas of leaking are:
(a) the pan. But I see no leakage around the transmission fluid pan or the gasket.
(b) dip stick tube. I looked under hood and cannot see the bottom of the dip stick tube. to see the bottom do i need to remove any part?
(c) transaxle oil lines. I have not checked because don't see them under car. do you know where they are located?
(d) speed sensor. does anyone know where it is located?
(e) differential drain plug. once again where is it located?
5) If you are facing the vehicle fluid drops come down from the two 10mm bolts (which appear to hold a cover on transaxle) less than 3 inches to the left of the transmission fluid pan.
6) Up top when I look down under hood I see no wetness.
7) transmission shifts fine.
8) underneath leak drops hang down from 10mm bolts at bottom of transaxle, all thin wetness around and higher up . so it appears be from the transaxle or something above the transaxle.
9) 11/30 I noticed the two 10mm bolts were not rock hard tight so I tighten them with my boxed-in wrench (there was small movement). but later after vehicle was driven I noticed it did not help.
10) 12/2 we drove it to church about 17 miles, after service appx 2 hours later glanced underneath and saw fluid about 2 inches across. so it's not leaking real bad at least not yet.
11) 12/2 rechecked tran fluid level and still looks within acceptable range.

Any advice would be appreciated. Thanks in advance. If you need more info or don't understand anything please let me know.
 
Last edited:

billr

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#2
Do you think that lower panel would come off if you removed those two screws? I'm hoping that is the cover that allows access to the screws holding the torque-converter to the flex-plate. If you can get that cover off, see if you can get a better clue on where the fluid is coming from.

Want a guess? The seal at the front of the trans that rides on the torque-converter hub.
 

josiah

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#3
Thanks Billr. No, there is more holding that panel on, in addition to the two 10mm bolts there are two 14mm bolts. And that's what I can see without jacking it up.
I am on vacation tomorrow and plan to take a better look.
 

josiah

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#4
12/7 took another look.
1)jacked up Highlander to see underneath. I see the same hanging drops from the two 10mm bolts. The bolts hold a cover on the transaxle. As I said before the leakage is about 3 inches to the left of the transmission fluid pan (that is facing the front of vehicle).
2) Up top under hood I traced to transmission fluid dip stick tube down, with a flashlight shined down, and saw no wetness.
3) Under hood When I shine the flash light down I also saw what appeared to be sensors, but I saw no wetness.
4) Underneath I when I look up toward the front I can see wetness so the leak obviously starts somewhere up there.
 

billr

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#5
There should be an easily-to-remove cover somewhere down there, to allow access to the TC-to-flex screws. Find that cover and remove it, start peeking around inside the bell-housing. Am I correct in assuming the outside of the trans-axle is clean/dry enough that you would see if fluid was running down on the outside?
 

josiah

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#6
Billr,
With the driver side wheel jacked-up, on my back with my head under the engine and trans, I can look up and see noticeable misty wet trans fluid in the front (when I say front I mean the left side of engine and transmission facing the radiator), but it misty wet up high and drips down to the cover with the two 10mm bolts because that's the lowest point of the trans.
So there's a film of trans fluid all around that general area underneath. It's misty wet up high and descending down.
So it drips at the cover near the pan but seems to actually starts from higher up.
I wife is gone with it now, so I will try to take another look tomorrow.
Thanks.
 

billr

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#8
It sounds like you are going to have to clean things up on the outside there. Sometimes you can track down such a leak by stuffing a paper towel into the suspect area to act as a "diaper". If the towel gets soaked and the drip seems to slow at the lower area, you have a clue...
 

grcauto

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#9
Regardless of where it's leaking in there the tranny needs to be separated from the engine. It's either the converter seal, most likely, or the seal around the pump cover, maybe, or the converter shell itself although that's hardly likely as when the welds break around converter shell they pour fluid out.
 

billr

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#10
I don't think it is confirmed yet that the leak is inside the bell-housing. The leak may be external to the case and fluid is just ending up down there at bottom of the bell-housing because it is lowest point. That's why I am urging the OP to take off whatever cover there is and see if the inside area is dry or not.
 

grcauto

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#11
I don't think it is confirmed yet that the leak is inside the bell-housing. The leak may be external to the case and fluid is just ending up down there at bottom of the bell-housing because it is lowest point. That's why I am urging the OP to take off whatever cover there is and see if the inside area is dry or not.
Should be pretty obvious if there's a trail of fluid on the outside. If no trail on the outside then what's left?
 

josiah

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#12
I was surprised at the number of replies. Thanks.
Clarification->when I look under the hood I can see the usual OIL gunk, but I can only see down to the exhaust manifold.
When i get on my back underneath I can see the transmission fluid mist coating the transmission, which starts somewhere underneath the manifold and down.
But I plan to take another look tomorrow morning to see where it seems to start. Thanks for the replies. .
 
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#13
As you consider the possibilities of leakage in this area, don't forget to factor in wind conditions inside the bellhousing. When the engine is running/revving, there is a whirlwind that can cause any fluid to do things more "active" than merely running down and across the bottom to leak out at the cover.