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I've been keeping a low profile as I've been working on doing the gearbox swap on my driveway....(about half way through) but I thought I would share a picture of the drain plug when draining the oil from the gearbox:

View attachment 147422

Yeah that gearbox is goosed...and I don't think an oil change will save it... :ROFLMAO: At least 4 large curved very sharp shards of shiny steel - on the order of 8mm long by 3mm in diameter each. And I haven't even checked the level plug - which also has a magnet in these gearboxes...

Anyone game to take a guess at where the shards come from? Given their curvature and size I'm sticking with the chipped gear theory...

I drained the oil into a measuring jug and got exactly 1.4 litres so it wasn't short on oil. The oil is completely black and opaque so I don't know how much other metallic residue might be in it.

Of course Murphy had to throw a spanner in the works - in the last 2 days while the Leaf has been up on stands the 12v battery has gone completely dead - it was right down to 4v which was too low for my intelligent charger to believe it is a car battery and not a motorcycle battery. :(

I had to use my hobby RC charger to start the charging and get the voltage high enough for the other charger to believe it was a car battery. Chances are discharging so low has done permanent damage (Lead Acid batteries don't like full discharges) so I may be up for a new 12v battery at the end of this which is a shame as I've had no problems at all with the 12v battery in this Leaf.

The car had already sat for 3 weeks without being used with no sign of 12v battery discharge, (and I occasionally used the timed climate control which would give the 12v battery a 15 minute charge session) so I think what has caused it is following the procedure to disable the parking brake.

Normally you can't turn off the car without the parking brake locking automatically, for removal of the gearbox you don't really want the parking brake engaged - the Nissan procedure to avoid this is to put the car in neutral then pull a certain fuse under the bonnet before turning the car off - this cuts power to the parking brake actuator.

However I had noticed that while on the car was constantly complaining about "put the car into park" after I did this and I'm guessing that the ECU in charge of operating the parking brake did not go to sleep when the car was turned off as it was still monitoring the parking brake status. Hence the battery went flat. Argh!! So if you disable the parking brake using the Nissan recommended fuse pulling method make sure you disconnect the 12v battery soon after.

Anyway, back to work...
Eek, debris and all.
 

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Or just a plain manufacturing fault - that looks like the oil has got hot as well as the obvious bits of metal so it is more than a chipped tooth from abuse.
 

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And this is a low mileage vehicle as well?!? I'd be tempted to say its had a few traffic light grandprixes or just a hell of a lot of very short trips in its life.

Generally the fluid and bits like that are generally when boxes have got higher up in the milage for the same age. usually about 60k so just after the warranty and on taxi's as well..
Short trips shouldn't result in gear failures, something else going wrong here entirely.

I'd be suspecting a shaft alignment issue. Faulty machining on the gearbox????

Have you checked out the oil quality on the replacement box, pulled the magnets, flushed it through?
 

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And this is a low mileage vehicle as well?!? I'd be tempted to say its had a few traffic light grandprixes or just a hell of a lot of very short trips in its life.
Short trips shouldn't result in gear failures, something else going wrong here entirely.
You all might recall that one of my pet-pieces I trot out and mention to people is that I would always be inclined to swap out the gearbox oil of any gearbox after 2000 miles, then again at 10000 miles if the car is a 'keeper'.

(The exact miles I mention probably vary, but you get the idea it's a couple of times early on)

I've been in this loop before looking at VM failure returns. Fact is that one in twenty or so of gearboxes have a load of metallic shit in them from new, don't ask me how or why or challenge me on gearbox manufacturers knowing their business, fact is if you were to swap out oil from 20 brand new cars at 2000 miles, you'll likely find one with some 'manufacturing swarf' left in it.

Over time, this grinds around and causes damage. Maybe another one in twenty of those cars suffer some consequence early on from further damage, the remainder showing gearbox problems past 80~100k miles, put down to 'old age'.

So in the order of one gearbox failure per 1000 cars of a few years old, usually showing up shortly after warranties end. This is put down to 'random chances' and ignored, usually blamed on abuse by the owner. I've never understood this.

Again, yes I know there is a metallic sump plug but these never seem to get rid of the fine crud which remain in a colloidal like suspension (blackened oil). Over time everything just wears and gets bad.

Ignore me as you wish and tell me I don't know things, but my recommendation, often repeated here, is sage; swap out gearbox oil of new cars after a bit of running-in.
 

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In fifty years of car driving, I've never changed the oil in any gearbox or differential unless on the service schedule and never had a problem and there isn't any proof that changing the oil prevents them.
 

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Ah, good old Japanese build quality.
In fifty years of car driving, I've never changed the oil in any gearbox or differential unless on the service schedule and never had a problem and there isn't any proof that changing the oil prevents them.
That's not what he said.
 

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Ah, good old Japanese build quality.

That's not what he said.
He said:
Ignore me as you wish and tell me I don't know things, but my recommendation, often repeated here, is sage; swap out gearbox oil of new cars after a bit of running-in.

I'm saying I never did and had no issues.
 

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He said:
Ignore me as you wish and tell me I don't know things, but my recommendation, often repeated here, is sage; swap out gearbox oil of new cars after a bit of running-in.

I'm saying I never did and had no issues.
You clearly don't understand why he does this, do you?
 

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I'm with @freddym , I think there's something other than just a possible gear tooth failure going on. Something like a tight bearing, shaft misalignment from a manufacturing defect or similar seems to be a more likely cause, especially as it looks as if the gearbox oil may have cooked a bit. The gear tooth failure (if that's what it turns out to be) might have been caused by this, perhaps slight misalignment causing the gears to bind, or not properly engage.

Either way, it's fascinating hearing about this saga unfold, and I look forward to a happy ending.
 

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My past two g/box issues/failures had nout to with the fluid so doubt this is either. Only ever changed the fluid once before inline with the service schedule and it was rank, hence why the Leaf will get done whether it's required on not for my own curiosity.
 

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Discussion Starter · #192 · (Edited)
Short trips shouldn't result in gear failures, something else going wrong here entirely.

I'd be suspecting a shaft alignment issue. Faulty machining on the gearbox????
Yeah, short trips means nothing for an EV gearbox. There are no gear changes happening just a constantly meshed reduction gear. Kinda hard to destroy it really, especially when this model of Leaf is only 107hp and it's the same gearbox used in the 215hp Leaf 62...

Got to be either a manufacturing defect such as swarf left in the gearbox from new, a hairline fracture in a gear or bearing roller etc. Not normal wear and tear.
Have you checked out the oil quality on the replacement box, pulled the magnets, flushed it through?
Eh ? The replacement gearbox has of course been drained before it was sent to me so I can't check the oil quality in it. :LOL:

I have had all three plugs out of it though, the two magnet plugs had a tiny bit of fine particulate debris on them - about what you'd expect but of course if there had been worse when the gearbox was drained and removed from the donor car they could just as easily have wiped the plug clean before re-inserting it, so I can't really take anything away from that - although it's unlikely they removed the level plug when draining so assuming that one is untouched then it was ok.

So I'll just have to see how the new box goes. What I may do though assuming all goes well is do another oil change on it after 1000 miles to check the condition of the oil and the magnet plugs - doing an oil change on these is very easy when it has easily accessible filling, level and drain plugs. The biggest hassle is removing that under tray, although mine came away fairly easily - only the bolt at the very rear had a rusted thread that was a bit stubborn.
 

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Discussion Starter · #193 ·
He said:
Ignore me as you wish and tell me I don't know things, but my recommendation, often repeated here, is sage; swap out gearbox oil of new cars after a bit of running-in.

I'm saying I never did and had no issues.
That is what statisticians would refer to as an inadequate sample size... :ROFLMAO:

You could just as easily have said you never wore a seatbelt in 50 years of driving and you're still alive and have never been injured. That says nothing about whether wearing a seatbelt is a good idea or whether it saves lives.
 

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Discussion Starter · #194 ·
Here are the bits removed from the plug. I have to say it does look a lot like swarf…

147432
 

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That is what statisticians would refer to as an inadequate sample size... :ROFLMAO:

You could just as easily have said you never wore a seatbelt in 50 years of driving and you're still alive and have never been injured. That says nothing about whether wearing a seatbelt is a good idea or whether it saves lives.
Correct but the opposite is also true.
I also know of no friend, relative, or aquaintance who had gearbox problems.
I'm not saying you shouldn't change the oil and maybe the Leaf's gearbox oil should be changed. If I decide to keep mine after the PCP is up, I may well change it.
(I have always changed the engine oil more frequently. especially when the service intervals are the so called 'extended' ones)
 

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Discussion Starter · #199 ·
Correct but the opposite is also true.
I also know of no friend, relative, or aquaintance who had gearbox problems.
I've had auto box problems on two cars now - one which was terminal - oil changes reversed the symptoms for a while and kept it going for a few extra thousand miles but a bearing in the torque converter eventually failed, and on the second car it started to exhibit a lot of nasty symptoms - a few oil changes and a little bit of additive (Lubegard Red) and that car has done 15k miles since then and is still running fairly well several years after I thought the gearbox was a gonner.
I'm not saying you shouldn't change the oil and maybe the Leaf's gearbox oil should be changed. If I decide to keep mine after the PCP is up, I may well change it.
(I have always changed the engine oil more frequently. especially when the service intervals are the so called 'extended' ones)
Oil changes for an EV gearbox are (or should be) nowhere near as necessary as an ICE autobox as the oil is not (a) being used as a hydraulic fluid in a very precise and delicate valve block which is prone to jamming, (b) not being churned up in a torque converter, (breaking down the oil molecules mechanically) (c) not being used as a heat transfer/cooling fluid, (auto box oil gets up to around 100C or more) etc...

The oil in an EV box lives an easy life by comparison. But I think you're missing the point @donald is making - he's not advocating frequent oil changes through the life of the car, just a couple at a very young age to check for and remove swarf etc. Once those first one or two changes are done the oil should last a long time as it is not being abused in the same way that it is in an ICE auto box.
 

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The oil in an EV box lives an easy life by comparison. But I think you're missing the point @donald is making - he's not advocating frequent oil changes through the life of the car, just a couple at a very young age to check for and remove swarf etc. Once those first one or two changes are done the oil should last a long time as it is not being abused in the same way that it is in an ICE auto box.
No, I hadn't missed Donald's point, I just said, I'd never experienced any problems with new or used cars.

I agree, EV gearbox oil should have an easy life apart from the torque going from zero to max much quicker than on an ICE vehicle. If it's the same gearbox on the E+ Leaf, I wonder how long it will last?
 
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