Electrek article about Model B motor repairs

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hallcp

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Jan 7, 2019
Messages
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This article https://electrek.co/2020/06/12/when-an-out-of-warranty-ev-fails-who-you-gonna-call/ in Electrek has a nice discussion of the fatal motor problems afflicting some Model B's. Tony Williams of "QC Charge" in California gives the best explanation I've seen of this problem. I believe Tony has been mentioned before in this forum, but some years ago (correct me if I'm wrong).

As detailed in the article, the cost for this fellow to ship to CA, get the car repaired, and shipped home was $5000. Although I don't see where the owner is located, so that's not much help.

I can tell you from personal experience that it's pretty easy to have a car picked up and driven cross country. I had a smart fortwo brought from Boston to Raleigh, NC for about $600. But California would be a longer trip!
 
Hallcp,

I dropped in here to post a link to that Electrek article, but you beat me to it. Well done!

I shipped a personal vehicle from Chicago to California by rail. I think it was less that $1,000. Back in 1989. YMMV.

Peter,
 
hallcp said:
This article https://electrek.co/2020/06/12/when-an-out-of-warranty-ev-fails-who-you-gonna-call/ in Electrek has a nice discussion of the fatal motor problems afflicting some Model B's. Tony Williams of "QC Charge" in California gives the best explanation I've seen of this problem. I believe Tony has been mentioned before in this forum, but some years ago (correct me if I'm wrong).

I've reread the article because some of the technical "facts" just don't make sense to me. This may be due to overzealous editing for the article, or some glossing over of details by the author and his source.

For some reason that link no longer works tonight, I wonder if someone else challenged the piece?

My observation is that there are two distinct failure modalities for MY2014 MUs. Firstly, we have the flooded coolant problem, where electrically conductive coolant shorts out the inverter, basically an electrical fault. This seems to be the majority of failures reported here. Secondly, there's the Motor Whine problem, where the vehicle makes a progressively louder noise until it quits. From MBUSA's point of view, where they do module-level diagnosis and swapping, either case requires a completely new MU.

However, the motor whining is caused by failure of the main bearings that support the rotor inside the motor. While it is the only part of the motor that spins, it does drive the transmission gearing, so its wrong to say there's only one moving part. One reason for the failure of MY2014 Tesla made motor units was reported as incorrect tolerance on the machining for the bearing supports, leading to binding and eventual failure.

Another factor with an AC induction motor (the type used by Tesla and other EV drive trains, but not the Tesla Model 3 which uses a Permanent Magnet Synchronous Reluctance Motor or “PMSRM") is the electrical charge formed on the rotor itself. Here's a scholarly paper explaining the problem.

This results in electrical arcing between the rotor and stator or motor frame. Which leads to premature failure of the bearings, as they are the only electrical path between the two. Tesla uses a high-tech electrically conductive brush to provide low electrical resistance and direct the current to bypass the bearings. Obviously, bearings could still fail due to other mechanical issues. Other solutions include electrostatic shielding, as cited in the paper above.

Collectively, we are early adopters of EVs, particularly the MB B250e. The price for being first in is often we are the first to find bugs.

Peter,
 
Mercedes isn't a great brand to own out of warranty. I know this from painful and expensive experience. My husband has a 2016 GLC300 and both of our cars recently went out of warranty. Since they both are low mileage, long since paid for, and well-loved, we decided to keep both for the time being. Therefore, we bought extended bumper to bumper warranties on each. Interestingly, the original sticker price was almost identical for both cars - around $52k. The warranty for the 2016 B250e was significantly more expensive than for the GLC300. Still, I feel much better about keeping this vehicle knowing that if I ever do need a motor replacement, it's a small deductible away. Side note, I used to own a very low mileage 1978 280CE that was flawlessly built and reliable. It didn't have as many electronic control modules and computers of course.
 
Greetings!

I am looking to buy a 2017 B250e with 19k mikes on it. MB quoted $7k for purchased MB extended warranty for additional 3 years! Have you had any luck with other extended warranty companies?
 
That seems high to me as well. You might search the posts on this and use the PM feature to email folks who have bought extended warranties like you are looking to do. These days, the traffic on this forum is running low so try the PM feature.

Good luck. I am looking to buy my 2017 off lease and am also considering an extended warranty but will skip at that price as I am hoping to snag mine at a number in the teens.
 
My dealer here in Cary sold me a 3-yr extended warranty on my 2013 for $2760. Seems like mine would have been more, since my car is older. I had about 23K miles on it at the time.
 
I paid $6500 for a 5 yr / 60000 bumper to bumper with a $500 deductible. It's $144/mo and I figured that was well worth the piece of mind given the random motor issues these cars can have. And it's fully prorated and refundable if I don't keep the car for 5 more years.
 
gtur said:
Greetings!

I am looking to buy a 2017 B250e with 19k mikes on it. MB quoted $7k for purchased MB extended warranty for additional 3 years! Have you had any luck with other extended warranty companies?

I also am a new owner and seeking to extend my warranty. MB quoted 7K as well but the finance manager offered another option named Mastertech for a little more than half the cost of MB coverage but only 50K miles. Will continue to look, and share of course.
 
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