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knightmb
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Re: How To: Reduction Gear Oil Change

Fri Nov 19, 2021 10:05 am

jaap wrote:
Fri Nov 19, 2021 4:07 am
So, I went back to the dealer this morning. There was oil leakage again and when opening the side plug, oil came out, even though they opened it last time too. So the leakage wasn't caused by over-filling, that's for sure. The leakage seems to come from the little tube, but also the dealer doesn't know why. It remains an unsolved mystery.
It's an EV, just isn't much to go wrong with it on the mechanical side. It's either the tube system as others have already said or some major manufacturing defect in the gear box that just is allowing the fluid to leak out, which would be a first here as I've never read about anything like that happening before. You would be the first. Before jumping to extremes though, my gut feeling says it's simple and the dealership is just over-thinking the issue. This issue can be reproduced, it's easy to remove that air shield at the bottom to see everything. I'm at a loss as to why they can't figure this out. :?
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voltamps
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Re: How To: Reduction Gear Oil Change

Tue Nov 30, 2021 7:11 pm

Might be easy enough to just replace the breather tube, it's a cheap part. Or at least inspect the old one, looking for plugging up.
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Re: How To: Reduction Gear Oil Change

Wed Dec 01, 2021 3:07 am

To continue the tale of the leaking leaf...

I went back to the dealer this Monday. They kept the car for two days.

The workshop manager was a bit less helpful then his colleague last time. He talked more about the end of my 3-year warranty (this week) and how doing your own maintenance might be a contract breach then about what they actually researched or found.

According to his story, there was still too much oil in the reduction gearbox (even though they already opened it twice and I did not refill anything in between). They replaced the oil with 1.35 liter of genuine Nissan oil. They also replaced one part: number 290T7X (BRUSH ASSY) because Nissan told them to do so. That is not the breather itself (part 38322M) but it's close. They gave me this printout from the workshop manual:
Image
Image
Next episode: In two weeks I will bring the car to the dealer again so they can check if it's still leaking. The workshop manager made me promise not to touch anything in between (I think he suspects me of secretly overfilling the gearbox at night).

To be continued...

nlspace
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Re: How To: Reduction Gear Oil Change

Wed Dec 01, 2021 6:04 am

Looking at the FSM it appears that the breather is for the earth brush housing and not the gearbox.

So there should not be any oil in the earth brush housing unless the seal on the main gear shaft is leaking. If it is leaking then oil can get pumped into the housing with no way to return to the gearbox. The leaked oil fills the brush housing and then pushes up into the breather tube, then blows the tube off the breather as the oil pressure increases.

The caution notes in the FSM mentions that there should be no oil on the brush surface and not to even touch the brush,
• Degrease shaft surface (brush contact surface) (A), and verify
that there is no dust or other substance on it, then install the earth brush.
• Degrease brush surface, and verify that there is no dust or
other substance on it, then install the earth brush.
• Never reuse O-ring.
• Never apply oil to O-ring. Verify that there is no oil on it, then install O-ring.
• Never touch brush area.
• When substances such as oil and dust are adherent to the
shaft surface (brush contact surface), remove them and
degrease the shaft surface to install brush.
• When there is corrosion on shaft surface, remove corrosion
to install brush.
When reusing with original parts, never allow oil to contact brush area.

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Nubo
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Re: How To: Reduction Gear Oil Change

Wed Dec 01, 2021 10:03 am

jaap wrote:
Wed Dec 01, 2021 3:07 am
...
Next episode: In two weeks I will bring the car to the dealer again so they can check if it's still leaking. The workshop manager made me promise not to touch anything in between (I think he suspects me of secretly overfilling the gearbox at night).
...
Seeing as how any excess simply leaks out of the fill hole, you'd have to be fairly dedicated to the task to pull this off. :lol:
I noticed you're still working with polymers.

LeftieBiker
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Re: How To: Reduction Gear Oil Change

Wed Dec 01, 2021 11:33 am

I think he's also parking the car on the side of a hill, with the fill hole(s) on the uphill side. ;)
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Nubo
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Re: How To: Reduction Gear Oil Change

Wed Dec 01, 2021 2:21 pm

LeftieBiker wrote:
Wed Dec 01, 2021 11:33 am
I think he's also parking the car on the side of a hill, with the fill hole(s) on the uphill side. ;)
Well we covered that. I think this dealership is either clueless or uninterested judging by their reliance on incantations ("save us, oh Genuine Nissan Oil") and their readiness to blame it on the customer.
Anyway I think nlspace nails it. It's an air breather and there shouldn't be any oil in the space it communicates with (brush housing).
I noticed you're still working with polymers.

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Re: How To: Reduction Gear Oil Change

Fri Dec 03, 2021 9:06 pm

From looking at the exploded view and reading the service manual, it is clear that the intermediate shaft extends into the brush housing so that the brush rubs directly on the shaft. Either there is a shaft seal between the brush housing and the main gear case or it is normal for oil to get into the brush housing. Even though the manual discusses degreasing the shaft surface, I suspect there is no seal and the vent tube on the brush cover is truly a vent for the whole gear case. If so, then replacing the O-ring, brush cover, breather hose, and breather should eliminate the oil leakage.
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nlspace
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Re: How To: Reduction Gear Oil Change

Sat Dec 04, 2021 6:53 am

Ben Nelson dismantled a gearbox and there was no oil in the brush housing when he removed the cover (seen at 2:09). Electric brushes won't work well with an oil film on the contact patch of the shaft. The internal rubber seal can be seen at 6:28.

Also you can see the oil ports and channels in the housing for lubrication of the bearings. If the return port was blocked then that might be another reason for oil to get pumped past the seal into the brush housing.

https://youtu.be/L5WhB7uQLzY?t=129

https://youtu.be/L5WhB7uQLzY

GerryAZ
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Re: How To: Reduction Gear Oil Change

Sat Dec 04, 2021 9:22 pm

It is interesting that neither the Nissan online parts catalog nor the exploded views in the service manual show the oil seal on the intermediate shaft. Also, the text of the service manual does not discuss that oil seal. I wonder how the main part of the gearcase is vented.
Gerry
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