2019 Kona EV Motor Noise Issue

New member, first post is bumping this from a year ago, lol, wondering if there is any confirmed cause for GRU or motor noises and failures.
My wife has a 23 Kona with 13,700 miles. It is a 3year lease but, depending on the economy and car market, she may decide to buy it at the end of lease.
After reading all this, I got curious about the oil condition and changed it and installed a magnetic drain plug. The oil was dark when in a container, but looking at a thin layer on my finger, it was fairly normal looking with some dark particles noticeable. The car did not have any noises and we did not notice it being quieter, but we both think it has a slightly smoother operation. I used Liqui Moly 5100 75W gl4 $22.00USD & the plug is Dorman 090-178CD $13.00.
Thanks for all who contributed here.

 

There are perhaps 200 posts discussing this subject within the top pinned thread but since information still trickles in every week from multiple forums I'll summarize the situation as I know it today.

The motor noise was determined to be tail-bearing outer race spin and lubricant failure by YouTube channel Auto Repair Videos. I also spent time looking at the bearing selection just a few days ago and found that there is one deficiency regarding the bearing size chosen, essentially that it's too large for the light loading conditions present in the tail-end position. The exceptional YouTube mechanic making the videos mentioned above has also rebuilt several Kona/Niro GRUs and those have never required more than replacement bearings as the gears remain undamaged, leaving us with the important clues that the GRU noise is due to the bearings and not the gears.

I've personally been studying the GRU failures for more than 2 years and the evidence shows that the internal factory magnet is not working as it should to permanently sequester the copious steel particles normally shed off machine-hobbed gear teeth during break-in. The result of that contamination is damage to the ball and roller bearings which reduces their useful lifetime. But it's still a matter of chance as to if any particular Kona develops an audible noise as a result within the expected vehicle lifetime.

My theory is that this happens because Hyundai/Mobis did not restrain the internal magnet securely but rather left it loose in a pocket to rattle around.

Steel particles will only stick to a magnet when they are fresh and during driving will find that magnet (just by chance) within minutes. But if they are subjected to any sort of mechanical working that attraction is much reduced. While stuck to the moving magnet, captured particles wear against a rib at one side of the aluminium pocket until their magnetic attraction becomes too low to keep them in place. When they return to circulation that's when repeated ingestion by the bearings does the damage to the raceways. The oil shows very small non-magnetic black particles and high PPM levels of iron.

Video images of the magnet in my own Kona show it to be relatively clean despite the car covering 27,000 km. It should in fact have a significant loading of particles held in place for the life of the EV. I take that as evidence of the inefficacy of the magnet regarding its intended function. That is a huge problem as the gearbox relies on that working properly.

The reason your oil is as you described is because all of the above processes have completed. The vast majority of first oil change reports are the same once past approx 10,000 km, including my own 2019 at 19,000 km (11,800 miles). Oil changes at much lower kms (see Ozkona's photo at 1,000 km) show the process in mid-stream with both visible particles and blackened oil present. The reason for the blackness is not confirmed but the high volume of aluminium found in nearly all used-oil lab analyses is a prime suspect, noting that there are no normal aluminium wear surfaces present in the GRU.

Specific to your Kona, I have to mention that we have vetted the two recommended magnetic drain plugs on the basis that gearbox applications have an important requirement - that the magnet has zero chance of breaking off inside the GRU. Most plugs are designed for engines and automatics where damage is unlikely should that happen. The Nissan Leaf uses a protruding magnet similar to the Dorman part and it may be just fine. But, in both that application and the Kona, the oil flow is violent near the drain and fill openings and a magnet protruding into that space will be subject to a dynamic loading situation, just like a chimney in a high wind. This is not the case in an engine or automatic transmission as the plug is located in the oil sump. If that magnet breaks off your Kona will suffer a catastrophic drivetrain failure. I'd be remiss as an engineer to not highly recommend that you change this as soon as possible to either the Votex or Toyota parts that are short and remain out of the oil flow. The risk may be low but you need to know that it's not zero.

As for buying the car at end of lease, although the GRU bearing damage has been done the chance of a noise problem from the GRU is actually very low. I think the 2023 is very unlikely to have a motor noise because the newer motor part numbers indicate that Hyundai found a problem early on. If you have the (unique to USA) 10 year warranty you've really got nothing to worry about.

Reference videos:

 

@KiwiME I just had the GRU and traction motor replaced under warranty at around 105,000km in my 2019 Kona after the initial motor mount repair did not resolve the ticking sound. From reading some of the previous posts it sounds like it would be prudent to replace the gear oil sooner than later and use a magnetic plug?

 

"Prudent" is an understatement according to the OzKona's experience! I'd suggest no later than 500 km and then another around 1,500 km.

The progression of the processes of particle shedding, the break-down of those into a non-magnetic state and then on to a black dust seems to happen way faster than I thought, probably done and dusted in well under 10,000 km. To minimise bearing damage the first 1,000 km is the most critical.

And, yes, a magnetic plug will help in the first 1,000.

 

Did Hyundai ever change anything to eliminate the problem?

Sent from my SM-G998U1 using Inside EVs mobile app

 

No, based on this evidence.

https://www.insideevsforum.com/community/index.php?threads/repair-issues-and-fixes.7097/page-39#post-205202

 

Just got the GRU oil test report back from Blackstone Labs, being tests run on the original oil after 36,006 miles which was replaced on 2023 November 29 on my 2019 Kona Ultimate. Report says Iron (at 218) and Aluminum (at 30) amounts are "high", as I expected after reading these threads, KiwiME's graph, and seeing the black color of the drained oil sample. Report attached. Replaced with the Redline MT-LV 70W-75W GL-4 synthetic gear oil and the Toyota magnetic plugs at drain and fill ports.

Blackstone report Comment:
"We haven't seen a lot of these samples, so universal averages are still being built. That said, this is the factory fill, so this report probably wasn't going to look very "average" to begin with. It can take a few oil changes before all of the extra metal produced by the wear-in process fully washes out of the system.
Silicon is from sealers/lubes used during assembly. The physical properties of the oil were normal. The viscosity read in 70W spec, and no water was found. 0.4% insolubles indicate minor oxidation. The TAN read at 4.3, showing some acidity."

Thanks for relating all your experiences and giving advice! So far this Kona hasn't had the "wheel of fortune" noise.
Any recommendations as to when I should next replace the gear oil?
And any wisdom on what the regular interval should be after that?

 

Thanks, David, I've included it on the graph, which is at this link. The markers are at the equivalent of 58,000 km. Compared with the other 18 results, iron is average while aluminium is very low.

As you've reached moderate miles you're well past break-in and can pick any convenient interval for future changes. Assuming continuing your current miles/year I'd suggest perhaps in 2 years or 15-20k miles. It will always come out black with minor debris on the two magnets, with neither being unusual for this gear reducer.

As a personal note, I lived in Ithaca as a youngster in the early-mid 1960s while my dad was an assistant professor at the Cornell astronomy department. We first lived in the Winston Apartments (Sapsucker Woods area) then later in Cayuga Hts.

 

I really appreciate the expertise, thought, and experiences brought by all to these discussions! Many thanks for adding my oil test results to the graph, KiwiME. I wish there were a hundred plotted results. For my results, I have no idea why the aluminum is so very low, unless the oil sample was taken at a moment in the draining when less of that element was present? Also, I remember decanting some of the oil from the top of my sample jar into the tube for testing _without_ stirring the oil beforehand, and the jar had been sitting for several weeks before I got the tube to send it for testing. But if much of the aluminum had settled out, why hadn't the iron?

And also thanks for that personal note! Oh, you lived over on the "cigarette streets" near Sapucker Woods? Cornell's Laboratory of Ornithology built a wonderful building for watching the birds on the shore of the pond in Sapsucker Woods, and they've expanded the walks through those woods. I live on South Hill, just 12 minutes' walk up from the Commons. Lots of changes, not all for the good, in Ithaca -- the 4-story height restriction that made this small city so personal has been eliminated, so now 10-11 story buildings loom over the Commons, and Collegetown has some huge buildings as well. C'est la vie. For my part, I had a fabulous 6 weeks bicycling and taking the trains around the north and south islands of New Zealand from late December 1985-early February 1986! I still ride bicycles -- just this fall added a Velotric "pedal-torque-assist" e-bike, which at 36 lbs is still light enough to travel on the hitch-mounted rear bike rack on the Kona. I do wish the rear camera on the Kona were mounted as high as it was on my 2017 Chevy Bolt, because the folded up bike rack never interfered with the camera on that car. Still like the Kona, though, and I even imagine it runs smoother!