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Leaking ATF - Mystery of where to check?


DanF.
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2004 Pathfinder 3.5 4x4 Automatic

 

There is a sizable leak that coming from somewhere not visible on the bottom of the transmission/transfer case itself. It is as if there is a pressurized leak spraying up and over to the passenger side, between the two doors. It is coating the underside of the Pathfinder, but not actually leaking down from the transmission. It's getting difficult to figure this out.

 

Several months ago my wife brought it to her mechanic who said that the 4WD sensor was leaking. After replacing that sensor with a new part the leak seemed to go away, until a couple weeks ago, and now the leak is happening fast enough where it's causing issues with how the transmission operates. It is currently spraying out onto the bottom of the passenger side in the same place as before, and causing the same drip pattern on the ground when the Pathfinder is parked.

 

I don't normally drive the Pathfinder (wife's rig) and have to rely on her description of the issue. She finally admitted that it was shifting weird and stalling out at STOP signs. I drove it yesterday, and while checking the fluid level found it was not even registering on the dip stick. Awesome.

 

Once I filled it up with Dexron III ATF the transmission shifted normally and operated as if there was no issue at all. So that's nice.

 

Her mechanic swears that he can't find the source of the leak, and I'm not too fond of his lack of ability since he seemed to have no problem finding the previous leak. He claims that sometimes the transmission just runs low after a lot of driving. WTF?!?

 

So, my question is: Where are the possible places where the transmission could be leaking from?

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OK, thanks for the suggestions guys. Where are the lines located on the transmission? I've got a ton of snow outside now, and am going to have to wait until there's a bit of better weather to do any investigation.

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I don't know on that particular tranny, but it will be two lines coming off of the side and running forward towards the radiator. It should be the only lines coming off of the transmission.

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I don't know on that particular tranny, but it will be two lines coming off of the side and running forward towards the radiator. It should be the only lines coming off of the transmission.

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The trans lines will be coming from the right side of the case and heading up toward the right side of the radiator.

But there is another possibility. You assume it's pressurized fluid because of the way it's flung all around. That's also what you will see if it' leaking out of the rear pinion seal. It will end up on the slip yoke and the super high rotating speed flings it off and all over the pace.

That's my vote. Most likely and obvious source by about 90%.

 

 

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Rear pinion would be a leak back by the differential, not by the tranny. It also would be gear oil, not ATF.

 

Rear pinion won't be flinging fluid between the front and back doors and running down the tranny body.

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I think he meant the output shaft seal on the trans. That would be flinging fluid at right angles to the output shaft, and unless there's something in the way stopping it from ending up on the driver's side, my money's still on the cooler line.

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I think he meant the output shaft seal on the trans. That would be flinging fluid at right angles to the output shaft, and unless there's something in the way stopping it from ending up on the driver's side, my money's still on the cooler line.

 

 

Yeah, the drip pattern is only on the passenger side. It's as if it's being sprayed up at the body of the truck, and traveling down the "frame rails" and dripping further out towards the doors/step-bars.

 

I'll be moving to rental house soon, and it has a small garage. I'll be able to jack the Pathfinder up and take a peak at the problem and try to find the issue. Right now our apt. parking lots are all angled, and covered in snow/ice. It's also too f$#king cold out to bother trying.

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I think he meant the output shaft seal on the trans. That would be flinging fluid at right angles to the output shaft, and unless there's something in the way stopping it from ending up on the driver's side, my money's still on the cooler line.

Yep! I did NOT mean to say pinion, but you figured me out.

 

And this can end up on just one side. Fluid will fling off right away at high enough speeds and can show up on one side due to the direction of rotation.

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Yep! I did NOT mean to say pinion, but you figured me out.

 

And this can end up on just one side. Fluid will fling off right away at high enough speeds and can show up on one side due to the direction of rotation.

 

It doesn't seem to be as far back as the transfer case/driveshaft connection. It's in the same exact area as the 4wd sensor location that was a leaking issue before.

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