Repair issues and fixes

It's less of a mystery when you consider that the Bolt also uses the oil to cool the motor and therefore that likely explains the additional volume. The oil is drawn through a plastic particle filter screen with a pump, cooled by a heat exchanger and then sprayed onto the windings. As far as I know, the Bolt is maintenance free regarding changing the oil. The overall design seems well engineered, IMO. Yes, problems are extremely rare but not zero from my readings of owner's forum chevybolt.org.

The Kona/Niro/Ioniq/Soul and Leaf gearboxes are simple splash-lubricated design like a 1950s BSA motorcycle, so the volume has to be carefully chosen to balance effective lubrication versus losses from churning. The Leaf oil volume is about twice Hyundai/Kia but that appears to be more about gear size rather than any other reason to have more capacity. Leaf oil changes on YouTube don't show any hint of blackness at fairly high miles.

As I mentioned above, I'm tending to think that the blackness in the Hyundai/Kia units may be related to electrical discharge across bearings by small currents escaping the motor shaft, an artifact of high-frequency PWM switching leading to phase imbalance according my research. This better explains the odd mix of failures we see past simple wear, especially now that we know that a magnet is present. There's no way to evaluate this without having the motor/gearbox in a laboratory situation with a dynamometer. Interestingly the Bolt has no obvious grounding system but I have no doubt GM knows their stuff in this regard.

 

Thank you for schooling me on the Bolt's design and the differences between it, the Leaf, and the Kona. Very interesting.

Is it that the electrical discharge is actually degrading the fluid itself or that it's damaging the bearings which in turn degrade the fluid? In either case, I don't think there's much we can do do other than preemptively change the fluid until Hyundai sorts it out. I'm curious if those who have done several changes already have noticed a steep drop off in in discoloration. That might give some insight into whether it truly is the electrical discharge (I would assume minimal drop off in discoloration over time) or just initial break-in (significant drop off in discoloration over time).

 

This phenomenon is relatively new to me and I'm unsure if the oil is degraded or simply discoloured from the continuous circulation of particles too small to be easily attracted to the internal magnet. The type of damage (see photo in earlier post) caused by frequent low-current discharge across an oil film would result in extremely fine debris. The (3) oil analyses we have don't indicate any oil oxidation so I'm leaning towards the latter cause of the blackness. I'd bet that the situation won't get better over time, only worsen as the grounding brush performance deteriorates.

As I mentioned in post #350 and 356 the next oil change carried out by myself or other concerned owners will be telling. I've done only about 500 km since, so it's a bit early for me despite my nagging curiosity.

 

I've just done a 1000km rural road trip, followed by a 2000km interstate highway trip. What a delightful care Kona EV is to drive - could not want for more in its price range.
I'm now on 8300km, so 1700 to go for my investigative oil change at 10,000km after the first two at around 4000km. Like KiwiME, champing at the bit but an earlier change would serve no purpose, IMO, so I will wait for the 10k to come up. I will get the oil analysed, both a fresh sample as a reference plus what comes out of the reduction gear box.

 

Today I replaced the reduction gear fluid in my 2022 Kona SEL based on the feedback provided in this forum -- thank you Kiwi and others. With only 1075 miles on the odometer, my dad (a former mechanic) and I were shocked at how black the oil was. It's a shame Hyundai hasn't come forward on this as there's clearly a design issue.

I'm thinking of replacing it again by 5,000 miles, but I'm curious what periodicity others are changing at (especially for the first few changes).

 

It's been hard to find useful internal photos of the E-GMP but I believe the motor(s) are oil cooled, which means a pump and that usually means some basic filtration. More to the point, I wonder if the grounding strategy is any different?

Good job - were there any discernible metal particles?
What change frequencies to use further down the line is still TBD but your thought of 5,000 miles sounds reasonable to me if you get there before we reach any conclusions.

 

I did look through the fluid fairly closely for any discernible metal particles and found none, which is good I suppose. I'm still stumped as to what it could be especially at such low mileage. Perhaps it is the grounding scheme as you've theorized, but it's hard to pinpoint simply looking at used oil. I'm hoping the answer is revealed with time as we collectively learn more -- it seems we're the few who are slowly uncovering the mystery.

 

Just to confirm that the oil is not black to start with I spent 30 minutes searching specs and part numbers, eventually finding an MSDS for the original fill. It was on an Australian dealership site here, but BTW note the price!


And here's a Yandex translation of the back of the bottle, nothing revealing here.


I also uncovered an oil and brake fluid change done on an Ioniq at 43,000 km, oil found black. But I was more interested in the brake fluid as it was just done the conventional way. I'm nearly certain the Ioniq has the same brake system we do.

 

Interesting. I certainly wouldn't classify the original fluid as "clear" after the drain, but perhaps it's not as fouled as we may think given that it's originally brown and not similar to the Red Line's color? Assuming others here have down more than one change already, I'm curious how discolored it was on the second or third change compared to the original color.

 

I think the vast majority of the first oil changes we have seen show the oil to be definitely blackened. There's been no trace of brown that I've seen.
Three of us have done two changes in succession and seen some trace of blackness due to residual oil but none yet have done a second change after significant distance driven. Patience is required until that is done; perhaps in a few weeks.

 

For what its worth ... my dealer told me to just follow the manufacturer's instructions. Here is their note:

"Good Morning,
Sorry it has taken a bit to try and find out the information for you.
Your vehicle takes 1.0-1.1 litres of SAE70W gear oil and the recommended interval is to inspect every 112,000kms
We do charge $55/per litre and $39.95 to replace.
As for the Magnetic drain plug, after looking into it for you, Hyundai does not supply them so unfortunately I am unable to get one on order for you.

If you have any questions or concerns please feel free to call or email me.

Thanks
xxxxxxxx
Service appointment coordinator"

I am sure changing this oil does not hurt, but car is warrantied for 5 years. If there is any problem related to the oil it should be covered. The magnetic plug, also a good idea, is hard to find.

 

To me there's something not quite right in knowing a problem exists, knowing a possible and cheap solution and then not doing anything about it. If you want to keep your car beyond the warranty period (I do - my car was an outright private purchase, not a lease) then preventative action would be wise. This reduction gear oil discussion was kicked off by an authorised Hyundai service tech who was replacing a reduction gear set that had failed at 40,000 miles (reply#119, page 6). The oil that came out of that gearbox was black syrup and his recommendation was regular oil changes to reduce the risk of similar reduction gear/bearing failure. At the rate we use our car we'd be well beyond the warranty period at 40,000 miles, so we, not Hyundai would be wearing the cost of repair. Plus there is the inconvenience of reportedly waiting for months while Hyundai sorts out warranty and parts supply. Regular oil changes are cheap insurance, IMO.

The magnetic plugs have already been found and are in regular supply. See @KiwiME's post 144 on page 8. You may decide they are not needed - it has been determined that there IS a magnet in the gearbox (post #338, page 17), it's just not in a drain plug. Adding another one won't hurt, though.

Do yourself a favour, Lars, at least change the oil.

 

1200km to go until my planned 3rd oil change at 10,000 (after initial change at 4000km, flush for 300km and 6000km driving). It will be a while though as we are about to do a bit of touring in our smelly, diesel-guzzling BT50 and camper

 

Not to change the topic, but does anyone know if skipping the blue coolant changes every 40K miles will void the battery warranty? The coolant change cost is rather excessive.

 

I was a attendee of the late Jack Richard's EVCCON. There was a speaker from Helwig Carbon Products, Inc. He worked in the design of specialized brushes to suit the needs of well known electric motor manufactures. He spoke about a requirement of a grounding brush to bypass the current from the shaft to ground. From what I can recall he said there is substantial current flow that if a brush is not present on the motor shaft, the current then flows through the motor bearings causing premature wear. I tried his work email, it got returned, therefore, I'm not including his name.

 

Just a guess but does the coolant become conductive as it ages? To test this point I measured the resistance of the coolant by putting a ohmmeter probe inside the reservoir and the other on ground. The reading was 1.6 M Ω after it settled after 1 second. It continues to slowly climb if left to count but I will ignore that. My Kona is a 2022 with 1020km. I will continue to check as times passes.

Maybe others can check and post their results.

 

I've watched a few of Jack's long videos. I didn't know he had passed away but frankly I'm not overly surprised. The exploding Leaf battery was the most memorable.

The Helwig website has some interesting commentary about the effectiveness of spring-loaded silver-graphite brushes (e.g, Leaf on gearbox intermediate shaft) compared with carbon-fibre ring brushes (Kona/Niro/Ioniq on motor shaft). Noting of course that they compete with vendors that supply carbon-fibre ring brushes.

But certainly the fragility of the Kona's arrangement concerns me. It's located close to the presence of grease and oil, there is no backup grounding path, and no easy way for the driver to detect a failure. The damage may not be noticeable until after the warranty expires.

The Leaf arrangement is a proper spring-loaded brush (composition unknown) with redundancy (there are two) but the location on the gearbox intermediate shaft puzzles me as gears are considered insulators when turning due to the oil film, so effectively the shaft is an electrically-isolated part. Despite efforts to determine if the motor is grounded elsewhere (it has to be) no-one on MyNissanLeaf.com seems to know.