Thoughts on earlier model S cars duration of drive units...

[rd929]

Alright...so after the rabbit hole of research, here is my question:

Pre-2015 Model S cars saw a very high incidence of drive unit failures, within 60k miles. Some claim the amount of actual drive unit failures was much lower, with instead the replacements happening due to "noises" and not a stranded on the road failure.

My hypothesis is this: any 2012-2014 on the road that has survived 60-120k miles on the original drive unit, is it safe to assume that since these are all out of warranty, that you're playing with fire and the drive units are just a matter of "how soon"?

OR

If the original drive unit has made it past the 60k barrier that so many did not, that it's probably a solid drive unit that will hopefully go much much farther into the 200-250k range? My only hesitation about an earlier model S is basically this...otherwise it seems safer to spend an extra $20k for a dual motor unit

Any thoughts or discussion would be appreciated

 

[Peter_M]

In my Dec 2013 Model S, Tesla replaced the motor under warranty in May 2015 at 34,400 km (installed rev M) and again in May 2016 at 51,900 (installed rev Q). Both times, the only symptom was a low grinding noise at low speeds. It was always drivable; I just asked them about the noise and they swapped the motor. No issues since then and the car is almost at 200,000 km. So if the Model S you're looking at has a rev Q or later drive unit, it's probably fine for a while at least. There are some very long threads on this - look for "motor milling noise".

 

[rd929]

In my Dec 2013 Model S, Tesla replaced the motor under warranty in May 2015 at 34,400 km (installed rev M) and again in May 2016 at 51,900 (installed rev Q). Both times, the only symptom was a low grinding noise at low speeds. It was always drivable; I just asked them about the noise and they swapped the motor. No issues since then and the car is almost at 200,000 km. So if the Model S you're looking at has a rev Q or later drive unit, it's probably fine for a while at least. There are some very long threads on this - look for "motor milling noise".

That's a related and then almost different conversation altogether: were the noises indicative of a premature drive unit failure, or were they just noisy?

Most of the 2012-2014 single motor listings I see are on the original drive unit. So that's where I'm trying to wonder if the original drive units, if they make it past that 60-65k miles range, should we assume they are solid units that will go 250k? Or should we just assume there is no rhyme or reason as to when the DU's can fail, and if it hasn't failed yet at 80-125k, it's just only a matter of time and a bit of a toss-up...

 

[Peter_M]

I don't know if my motors would have gotten worse if they weren't replaced. I think the issue had to do with inadequate grease or loss of grease causing gear wear, so probably they would have failed. I don't have the answer to your question - whether an old one that hasn't failed will continue to be OK. Maybe drop into your Tesla service centre and ask about it. If they were around when these issues were happening, they should know more. You might also be able to get them to check the history on a specific VIN (with the owner's permission), or inspect a car you're thinking about buying.

 

[rd929]

I don't know if my motors would have gotten worse if they weren't replaced. I think the issue had to do with inadequate grease or loss of grease causing gear wear, so probably they would have failed. I don't have the answer to your question - whether an old one that hasn't failed will continue to be OK. Maybe drop into your Tesla service centre and ask about it. If they were around when these issues were happening, they should know more. You might also be able to get them to check the history on a specific VIN (with the owner's permission), or inspect a car you're thinking about buying.

Yea I did see some people mentioning the lack of grease. I wonder if it would be a preventative measure on the single motor units that were larger to drop it down and possibly pack it with grease. The records are only obtained through permission of the current owner from what I read. I don't even know how useful it would be, since your indicators of a "failing" DU is the milling or whining noise so you'd notice it when test driving it anyways. I may reach out to some of these indie Tesla shops, I guess they may have the most informed opinion on this...

 

[ucmndd]

The two main reasons the large RWD drive units are replaced are:

1) Milling noise. This appears to be largely a nuisance, rarely leading to outright failure.

2) Failure of a coolant seal that floods the interior of the motor, corrodes everything and eventually fries the inverter electronics.

Lots of info on case #2 in this thread:

Out of Warranty Drive Unit Replacement and Cost

Hi Everyone, Sad to make this my fist post on here, but looking for some advise. About a week ago the DU started making that dreaded milling sound. Just all of the sudden. It is getting a bit louder as I drive more, even in just a week . I took it in this morning to the service center and they...

teslamotorsclub.com

 

[KevinRochester]

First post here, but have a story to add to the thread. I have a CPO late 2014 Model S 85. Have loved the car. Drive Unit and Battery warranty ended on Jan 2, 2023. On Jan 4, 2023 before noon (yes, 30 hours out of warranty), started receiving power alerts. Was told to bring it to the service center immediately which I did. They did not find any issues and reset the alerts. On Jan 12, I had a charge port failure and had to replace ($785). On Jan 21, had drive unit failure and had to have the car towed to service center. Tesla diagnosing drive unit failure not covered under warranty since warranty had run out. Yes, 30 hours post warranty. $7800 to fix. Now still trying to debate coverage with Tesla, but they seem to be taking a firm stance.