22 Kona - Reduction Gear Fluid Inspect vs Change

Almost certainly it's going to be either the motor or gear reducer, both somewhat common problems. The motor may have been improved in newer examples but there are still reports of occasional failures. The gear reducer cannot be repaired by simply changing the oil and this weakness is present (and remains) in all first-gen Kona EVs. For whatever reasons they have avoided rectifying either issue until the 2024 Kona gen-2 version.

There has been only one report that I've heard where Hyundai UK was obstructive in making good with repairs, and that was because (unrelated) scheduled general maintenance was not done precisely on time or miles, a regrettable tactic on their part, IMO. The owner had to pay around the equivalent of US$13k for replacement of both parts even though these design deficiencies are entirely Hyundai's mistake.

In the US you have the luxury of a lengthy full warranty that few globally have. When it's convenient book it in and they will replace the defective part(s). Ask for a loaner car and let them get on with the job.

If you do receive a new gear reducer you may be able to avoid that particular failure from happening again by having the oil changed at your expense, 300 miles and (if it was dirty) again at about 900 miles. You could always inquire if they will give you a good trade-in value for a new 2024.

 

The answer is variable depending on (a) whether you’re covered by a warranty and (b) the cost of that work, and (c) if the oil still contains metal debris.

Since you’re under warranty and (I assume) would have to pay for the oil changes I’d suggest once every second or third service is sufficient, at least until it comes out mostly clean.

If at any time you post a photo of the used oil sloshing around in a pan I can offer a more accurate opinion.

You can download my guide for reference here.
Don’t let the dealer overcharge for this service. US$ 180 is the most I would accept as reasonable.

 

Probably a dumb question, but can they put the revised/improved 2024 parts into a 2021 model?

I just got diagnosed with this issue (2021, 72,000 km) and just waiting for parts to come in.

Terrific document on the subject by the way, KiwiMe.

 

Well, thank you!

The gen-2 2024 Kona has no parts in common with the gen-1, it's a ground-up redesign that is similar to that used in the E-GMP range (Ioniq 5/6, EV-6) where the motor and reducer are closely integrated into a single assembly. Tesla went through the same learning curve and design evolution between the Model S/X and 3/Y.

When your Kona is repaired, assuming the gear reducer is replaced, you'll only need to change the oil at 500, 1500 km and then once every year or two ongoing and I believe you're unlikely to have further problems with that part. If by chance any of those oil changes comes out free of serious contamination, you'd be off the hook for any more.

It would be great if the dealer would provide that preventative maintenance at their cost but I won't be holding my breath. You could DIY or have a local shop do it. You could ask if they'd be OK with adding a pair of Votex magnetic plugs, ideally during reducer installation when it's easy (noting the tightening torque is lower).

As a related note, I was told last week by a local 2019 owner that he has had the reducer replaced 3 times since late 2023 because two replacements failed due to manufacturing defects, reportedly faulty gear hardening. The car is well out of warranty but fortunately our importer seems conscious of their reputation and is covering the cost of repairs.

 

Hello KiwiME,
I genuinely appreciate the helpful advise/information you have provided via various Hyundai Kona Electric forums. Consequently, I do not want to overwhelm you with more requests or demands on your time!
I had the misfortune of having the "wheel of fortune" sound on my 2019 Kona Electric ( "Hyundai Kona EV powertrain clicking sound" ) beginning at about 3,500 km, in late June/early July 2019. Months later in early December, 2019 (11,802 km), my dealership followed instructions from Hyundai's road engineer to remove and rotate the drive shaft 180 degrees precicely, and then reinstall it. Incredibly, that got rid of the wheel of fortune sound.

Fast forward to March 13/24 (odometer = 85,436), when I casually took my 2019 Kona EV in for a nearing end of factory warranty (5 yrs. or 80,000 km) inspection. While performing the inspection the technician detected problematic sounds during a test drive. He noted a whirring noise when accelerating and a rumbling noise when decelerating with regen braking. Reduction gear oil was black and had some flake in it. See TSB 22-EV-001H-1 https://static.nhtsa.gov/odi/tsbs/2022/MC-10225461-0001.pdf

I was in shock, to put it mildly, as I thought everything was OK -- not having detected any strange sounds myself.
Several days later the traction motor and reduction gear unit were replaced!

Since then I followed your advice regarding the reduction gear assembly (GRU): installation of a Votex - M18X1.5MM stainless steel magnetic oil drain plug with neodymium magnet, and fresh gear oil (Red Line Synthetic gear oil MT-LV 70W/75W GL-4 in 946 ml volume container). I've done this twice to date: after 912 km and then after another 2,540 km. In both cases the gear oil was black (unacceptable/problematic according to my local automotive mechanics who are not associated with Hyundai). BTW the reduction gear oil drain plug on the new reduction gear assembly from Hyundai (March 13/24) was not magnetic.

I have a friend who's a retired electrical engineer with decades of international experience dealing with electric motors in the fossil fuel industry. He was alarmed to hear about my Kona EV's black gear oil, especially after so few kilometers on a new traction motor and reduction gear assembly. I supplied him with links to some of your recent documentation on the "wheel of fortune" sound, as well as a link to "The weakest point of electric vehicles Kia Niro EV and Hyundai Kona Electric" by the Ukranian mechanic in the Auto Repair Videos YouTube Channel: (26:51)

Perhaps there may be more than a single cause of the wheel of fortune sound and black reduction gear oil problems, which can muddy the diagnosis? Are you finding that the blackened gear oil problem does eventually (consistently) disappear after 2-3 gear oil changes, before about 15,000 km on a new traction motor and reduction gear assembly (GRU)?

My electrical engineer friend suggests that there are probably several factors at play here in the oil blackening; not only shaft/bearing currents, but also gear design, high speed duty, inverter/VFD (Variable-Frequency-Drives).
When you can, please have a look at the PDF provided for downloading from https://www.est-aegis.com/applications/electric-vehicle-solutions/
(This PDF is too large (5.2 MB) to upload to this forum.)
Summary video: "AEGIS Rings for Electric Vehicles" (1:40)

A more general introduction to the business of shaft currents by ABB Motors and Drives U.S.:
"What are shaft currents and how to protect my AC motor" (5:49)

 

Thanks for your supportive words and I did view and comment on your video (using my YouTube handle) many months ago as you've likely deduced.

I've been down all these roads during my research and it's certainly true that it's not all conclusive.

The smoking guns are:
(a) that the factory magnet is almost always found clean on inspection (with a camera) when it actually should be loaded with particles;
(b) that numerous early oil change reports show significant visible particle content in the oil at around 1,000-5,000 km;
(c) that oil changes after about 20,000 are always free of particles but the oil is still blackened, and ...
(d) that in every case where the owner has had the GRU rebuilt that job is completed by only replacing the bearings, suggesting that the gears have not been seriously damaged.

It's entirely possible that the blackened oil is not directly related to the WoF failures but instead by either, or both, electric current discharge across bearings and/or aluminium contamination resulting from outer-race bearing spin at any of the four locations where that type of bearing is present. The high aluminium values in UOA reports tend to point to the latter being present. In one case I've seen video evidence of severe outer race housing wear at the input shaft motor-end bearing. But the oil blackness itself is not so much a direct concern. And, I've not heard of any cases where the oil discolouration has receded over time or miles, but a very, very small percent of examples don't have this symptom at all.

The Kona and Niro motors (unlike the Ionic 28/38 kWh) generally do have a ring-type carbon brush installed, noting that there is one study from a vendor indicating that this engineering solution is not as effective as a spring-loaded discrete brush acting on a dedicated plated surface on the motor shaft. But it's worth mentioning that it's also a solution that they happened to manufacture.

It's also problematic that the environment around the brush ring in the Kona/Niro is exposed to the road via a drain hole and subject to any contamination that happens to find its way in, nevermind grease migrating from the spline past the O-ring. It really does look like a last minute addition however and the technician at "CarRepairVideos" responded to me in a comment that "not all" Kona/Niros he's seen have this brush.

In one of his videos this exceptionally diligent technician does inspect the Niro motor bearings for current-discharge damage and doesn't find any, for what that's worth. I'm not entirely convinced of that result but I'm also not convinced that it can cause a GRU failure in very a short time, as we often see. A loss of grounding performance over time of the ring brush would suggest that failures also would increase accordingly, yet they don't appear to.

After chasing these issues for years I had to try and reach a conclusion. In my opinion the particle contamination frequently found early on is so epic in scale for a gearbox that it cannot fail to have an adverse effect on the life of the bearings. The end result, much further down the road, is simply a matter of how that initial particle damage tilts the statistical lifetime curve of each bearing.

It's also worth noting that the motor has its own bearing problems at the tail end, at least in early examples. That in itself is another study entirely and I've tried to avoid worrying about that as well.

I'll be changing my oil once a year at minimum and I really don't expect to have a GRU failure. I'm not as confident about the motor but either way I'm not in any hurry to move on to another EV.

 

Thank you for this helpful, detailed reply KiwiME -- very much appreciated. The link to the Munro Live video was also helpful; good to see Kia and Hyundai's new E-GMP platform motor assemblies are applying carbon brushes as well as ceramic bearings to address the critical need for traction motor drive shaft electrical grounding. My next step will be to find out how this important electrical grounding issue is dealt with in my newly installed (March 2024) traction motor assembly. In the meantime, I too plan on keeping my 2019 Kona Electric.