High-Pitched Motor Noise

So I just celebrated one year of ownership of this car, glad to see I'm not the only one still pissed about this damned hissing sound. To this day, I am still annoyed every freaking time I drive the car and am still considering it selling it, only thing stopping me is that this will obviously be at a loss of a few k$ but I'm not sure I care anymore to be honest. I have close to 30 k on the car now, I need to go back soon for a brake noise/issue (again) and will try a different dealership this time who sells more Kona EVs, maybe better luck there.

Should I try to ask/get them to change the "oil" inside the gearbox to see if that does anything/they find particles in there? And did I understand from a post above that changing the electric motor as actually fixed this for some people?

 

I feel the same way. I want to dump this car but I chose it for style and size. Both are perfect for me and the sound is annoying. Funny thing, my neighbor has an early Model 3 and I walked by it today while he was moving slowly and it has the same high pitched sound; just not as loud. They must have gotten better at mitigating it over time but it is there. I attempted a trade in offer for my ultimate at Tesla and they offered 22.5k and the KBB is 30k. Not a good deal to dump it for me. As long as it doesn’t get worse I guess...

I tried not to buy a generation 1 Kona since it was out for a long time before the US release. Figured these items would have been identified.

 

Procedure for replacing the eNiro gearbox (same part as Kona) oil is shown in this Korean blog entry. Auto-translated Link.

 

If you look at the untranslated page, the images are there. The pictures are sort of thumbnails, and if you click on the picture, you get a larger one

https://blog.naver.com/doohan500/221841433777

What sort of works is to kind of scan the original and the translated, side-by-side. That gives you an idea what is going on.

I can sort of summarize - it starts with a discussion of what the gear oil should look like, and wha the optimimum brand of gear oil to be used (with pictures of some of the bottles). Then there is a discussion about how to drain and change the gear reducer oil after 15000kM.

In this case, the oil was dark and had an unpleasant odor.

He was using a syringe of sorts to extract the some of the old oil and then inject new at the top (no picture of where the fill port on the top was).

He said he is not a professional mechanic - he borrowed a lift from someone he knew. It doesn't sound like he sent the fluid out for analysis.

Back in my VW TDI days, we used to send out motor oil from time to time - in my wife's old car, we were concerned about excessive wear on the camshaft due to some unfortunate design decisions that VW made. I could look and see whether the company that I used can also analyze gear oil or not.

 

The company that I used before for oil analysis is:

https://www.blackstone-labs.com/

Their webpage says they can do automatic transmission fluid as well as engine oil. That's not quite the same thing as a gear reducer, of course (but a lot closer than engine oil). There is a sample report you can see - it gives you an idea of the things that they test for.


If I were doing it, I would get them on the phone first to explain what it is that I wanted to test, but it looks like their standard report would cover most of the bases.

 

Can someone with more knowledge please read this article and confirm if this is connected to the high pitched whine that the Kona makes? https://www.manufacturing.net/home/article/13056843/whats-that-noise

Mine also makes this sound, though I've read this and a few other blogs reflecting few possible fixes, I haven't given up yet. I'm totally fine with the VESS sound, but this high pitched hiss needs to go away. Please let me know if this article makes sense to you--it seems to be pointing at a possible fix via a "conductive brush" or "hybrid seal":

"As this voltage is transferred to the motor, the variation in input power must be dissipated. The pulses create a capacitive-couple, common-mode voltage (CMV) on the motor shaft. This excess unbalanced voltage takes the path of least resistance to ground, which is most often through the bearings. Here, it exceeds the insulation levels of the oil film causing it to arc from the bearings’ inner to outer races. These voltage arcs act as tack welds on the outer races, and electrical discharge machining (EDM) pitting occurs thousands of times a second around the bearings, eventually resulting in failure from fluting damage (Figure 5). This damage creates the high-pitched whine referred to earlier as the bearing elements roll over the fluted races, much like a car driving over rumble strips.

To address this problem, manufacturers have added conductive brushes to traditional bearing isolators to prevent stray voltage from passing through the bearings (Figure 6). This shaft-grounding feature acts as the path of least resistance for the voltage to travel to ground without fluting the bearings. The brushes dissipate any existing CMV from the shaft and prevent any future EDM from occurring. Note that once a bearing has been fluted, a shaft-grounding bearing isolator cannot reverse the damage."

"Manufacturers have also solved this problem with a hybrid seal that is rated for conditions beyond the capabilities of traditional isolators. These flooded seals accommodate fully submerged lubrication levels and retain up to 7 psi of pressure, which is comparable to most general-purpose oil seals."

 

Hi Brennan, I've followed your posts through this and wonder if you can check out my recent post at the end of the thread? It seems that electric motor hisses do have a fix involving a "conductive brush" or "hybrid seal" -- do you know anything about this?

 

Mine makes the hiss sound even when accelerating at lower speeds (10-25 mph). I don't think it's solely a brake issue.

 

This article also speaks to an output choke connected to the VSD (variable speed drive) that would make the noise inaudible. Thoughts?

https://www.nhp.com.au/files/editor_upload/File/TNL/TNL-47.pdf

 

No doubt additional chokes would help reduce the noise, but three chokes that can handle the hundreds of amps peak current could be quite a large item to package, nearly the size of the 12V battery at a guess.

 

... and be sandwiched between the inverter and motor ...

 

Update on Kona whining noise.

I now have my Kona back after the dealer replaced the gearbox and the whining noise is gone. My Kona EV now sounds like the car that I bought 10 months ago!

I asked the mechanic if he could tell what went wrong and he said it was likely a bearing or something inside the assembly that had failed. They don't open the unit at the dealership but are required to send them to Hyundai in Korea for analysis. So Hyundai is obviously working on this. This is the second Kona he's seen like mine and he thought it was either a production flaw or faulty component inside the gear box.

So I now have a new gear box assembly and the annoying whine is gone. It had increased slowly over time to the point where the car was almost impossible to drive. Fingers crossed the fix is permanent....

 

Glad to hear things are good for you again.

Sorry to hear they have to send the old one back to Hyundai for "analysis". I was kind of hoping that someday we would get a chance to look at the insides in a lot of detail.

 

Does the Ioniq have this issue?

 

So, now I'm wondering how the 'whining' noise fixed by the gearbox replacement relates to the hissing noise (this thread), the ticking noise (the other thread) or possibly a new problem entirely? Whining could be due to a damaged bearing or gear teeth. The hissing noise would seem unrelated to the gearbox and the ticking noise seems to be cured by replacement of one or both of the motor and gearbox. And how does the difference motor p/n fit into all this?

 

I have a new vibration (it was a whine in winter) that is not the original hiss noise (that is pure harmonic noise) and it doesn't seem to be the tapping noise from the other thread.

Dealer says it's a bearing in the gearbox.

Now, to reply to the previous poster quoting an article on bearing currents:

I'm an electrical engineer and I work with this stuff in my daily job.

Bearing currents are a real concern with variable frequency drives and we must always ensure a proper installation and proper cables, filters etc. are used, otherwise the bearings will indeed get damaged.

I'd be very surprised that Hyundai didn't take this into account since it's a very well known problem in the industry, but yes, if bearing currents exist in the gearbox this will damage the bearings quite quickly.

Luckily for us the reduction gear is part of the electrical powertrain and is warrantied for 8 years.

 

As we discussed in the other motor noise thread, in Korea, where the car started production in 2017, some owners have had their gearboxes replaced up to 4 times already. Unlike the motor, the gearbox never got a new part number.

 

I was just sent a survey for one year ownership and highlighted these issues we have experienced. Stink since the car is beautiful besides.