Tesla repair expenses on older Model S / X -- PART 2: Drive unit/drivetrain, failures, replacements

Drive unit / drivetrain failures on older Model S / X can be very disruptive and expensive -- especially if you're out of warranty -- and there are new options in available for owners of vehicles using Tesla's "large rear drive unit" that should make the next drive unit you buy your last drive unit. We'll discuss why they break, what the design issues are with new and refurbished units and how you can make sure you get "The Good One."
Rear lower control arm replacement -- getting access to the speed sensor:
• Tesla Model S rear low...
Follow-up conversation in 3 parts:
1-- Battery concerns
• Tesla repair expenses ...
2-- Drive unit concerns
• Tesla repair expenses ...
3-- Sweet Spot to upgrade
• Tesla repair expenses ...
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[@markschultz9100]

I had my drive unit replaced under warranty in November of 2021, they did not install the Updated drive unit as it "wasn't available at the time". Now i'm worried my drive unit is a ticking time bomb.

[@steveschulzelectronicswiz]

The delete entails sealing off the Rotor cooling path within the manifold. The flyover tube you are showing is on all motors new and old and stays on the coolant delete part too since it moves coolant from the manifold to the top of the gearbox as in the original.

[@NZCUTR]

Agreed -- this was a misunderstanding from the original picture source that I repeated. The part number is the most reliable way to ascertain updated drive units. UPDATE: I am updating the edit of this video to remove the reference to the flyover tube.

[@jogriffin9347]

You guys are very smart with this can you please answer what is best year model x to buy so I don’t have to worry as much sounds like expensive stuff here please let me know Thanks

[@peteroffpist1621]

Agree thanks I have come to the same conclusion .

[@slartybartfarst9737]

I own a P85 bought new 2014 now 145,000 miles, as an ex engineer 44 years world wide in big auto. You are WRONG. Version "U" does not define the "tube" that is on all motors. The tube takes coolant to the gearbox, specifically the output bearings. The "U" drive units will be fitted with hybrid armature bearings using ceramic ball bearings that do not provide a path to ground for induced electrical currents that would otherwise galvanicly destroy the bearing along with other more minor enhancements. The coolant delete removes the need for the seal on the feed end of the armature shaft, this seal always seemed to me to have a failure mode that far outweighed the benefit, but Im viewing it from my use case. I live it the UK, it is not often that hot and there is rare opportunity to run the car at any where near the full load for any extended time therefore generating a large heat burden. To delete the coolant seal I will jack the car, remove the LH rear wheel and undo the aluminium gallery / top cross feed pipe nut. Once undone it is only possible to move the galley away from the motor rather than remove it as it hits the sub frame with the coolant feed tube still in the armature. Slice the feed tube off the gallery and remove the gallery for modification. Slice up the remaining feed tube incrementally as you remove it section by section. Machine the galley to accept a stainless steel turned plug and refit. When to do all this? Im a machinist and I have the machines and I wont do it unless its needed. Ive already inspected the encoder sensor, it was dry so I have a good drive unit. Theres nothing new here, weekly inspect your tyres and coolant level, save a fortune. Ive drilled a 3 inch hole in the plastic panel above the coolant header tank I can see the coolant level, if it starts dropping its going somewhere? Theres your answer do the mod now or do it before if you have the time / inclination, either way dont leave it till its too late, prevention batter than cure ££££

[@NZCUTR]

Prior comments already addressed the flyover tube -- but since no one reads comments, I'm updating the edit of the video to remove the reference-- but you're correct that it is not a visible reference of the coolant delete as I'd initially understood it. However, as you put it, you are WRONG that cermaic ball bearings are not a new feature to U revisions. The ceramics were added sometime circa late 2015 to refurbs and new production drive units-- after many were swapped under warranty for the "milling noise." It's unlikely that there are very many of the earlier non-ceramic bearing drive units still in service because of their high initial attrition rate. Your solution for the bypass is interesting-- especially since it would seem to skip the DIY-unfriendly process of dropping the drive unit or otherwise having to lift the car fully-- and if you ever actually perform this modification, please document via video and share! I would note that coolant levels dropping in an older S are not necessarily indicative of a drive unit seal. In fact, a far more common repair is that one of the coolant pumps has developed a leak. So while that is still alarming, it's not nearly as expensive a repair.

[@slartybartfarst9737]

@@NZCUTR Challenge accepted, I will document if I do the mod. My point on the coolant level, check it and if it drops do the mod. The risk /cost consequence for me is just too great to gamble it not the drive unit armature seal. There are a number of You tube channels showing slicing of the aluminium coolant gallery half way up so the off cut can be wangled out then others showing removal and plugging of the cross feed tube from a dropped drive unit and sub frame however I consider it easier to leave the sub frame in place loosen only the top cross fed tube fitting and by slicing the coolant feed tube getting the coolant gallery complete off the drive unit. I have a lathe I can make a plug to fit in the gallery (again there is one mod done like this but as I say the drive unit is dropped to do it).Of course the coolant feed tube into the armature could be hard steel and likely is so an off hand grinder may be needed to slice it up necessitating a lot of careful precautionary packing to ensure grinding dust does not enter bearings or the coolant passages. You will hear the cursing. Hopefully my coolant level never drops and I never need to do the mod. As far as I understood all U revision drive units have ceramic hybrid bearings, I dont know about any others I stand corrected if you are correct there is no way from any part codes you can determine if the bearings are ceramic hybrid, I guess thats a wait and see and to me a way less risky problem than the coolant seal design defect.

[@teachingmaterial2011]

Thanks for this video too?

[@gilgabo]

Great information. Thank you.

[@aussietaipan8700]

This is incorrect about the information on the tube that goes from the manifold to the gear housing, my 2015 model S has the original problem rear motor and it too has the same tube. The actual difference is the water tube that goes from the manifold into the stator on the old design, this is deleted on the U design so coolant now does not enter the stator section where the seal fails and coolant enters the motor, gear box and inverter. I have already modified my model S with the coolant delete and it runs well.

[@NZCUTR]

Correct-- I addressed this in an earlier comment: "this was a misunderstanding from the original picture source that I repeated. The part number is the most reliable way to ascertain updated drive units." There are a number of low cost ways coming onto market now to DIY a coolant delete. I've not yet seen a truly/easily done DIY-- but if you have a local mechanic with the right lift/tools and desire, this would be a good project to undertake. For shadetrees like me, the lift is the hardest part-- and I don't have a way to get the rear end comfortably and safely skyward enough that I could shimmy under it as necessary to DIY.

[@NZCUTR]

Still getting comments (from people who haven't read the prior comments) ... so I'm updating the edit on the video to remove the reference.

[@PKerusso]

I have a 2019 P100D. It’s making the windmilling noise. What causes that ?

[@NZCUTR]

Could be bearings? Could be differential? Could by the axles? There's a number of other non-drive-unit parts that can fail/wear out. While it *may* be true that EVs require less maintenence, I think the jury is still out on whether they require less REPAIRS. The high torque of a performance's DU is obviously going to accelerate wear just like any other high performance car.

[@PKerusso]

@@NZCUTR it’s in for a new RDU. Tesla tech said they just “ wear out”. Well it only has 42,000 miles😳

[@NZCUTR]

Uncommon... but I suppose anything is possible. Make sure you get a U revision! :)

[@pIrkezzz]

Electrical discharge inside the inverter. Does not affect your car and will not ever affect function. If you dont mind the noise just keep drive it, if still in warranty just fo and replace it at Tesla

[@NZCUTR]

Interesting... I think discharge/arcing was also the explanation behind the "balloon noise" when accelerating (esp. when cold) but that it was associated with the main pack contactors. Though my understanding was the noise indicated contactor wear and was to be avoided (lighten up the lead foot!)

[@berchang503]

My one year old 2014 model A 85 just took a shit. With only 60k miles. My question is, is it worth it to fix it. Tesla wants 9k. Also upside down on car loan.

[@NZCUTR]

All depends on your use-case, what broke, what your resources are. The trouble with Tesla repairs is that it's basically all cash business. Loan complicates every car decision (I have never had a car loan for this reason and bought only what I had cash on hand for), but a broken car isn't particularly useful either.

[@riccimason2363]

I have the same problem. My 14 S took a dump, and it's dead in the water. I'm concerned that the batteries are next. It's a beautiful car but, just a lawn ornament right now. Funds are too tight to pull the trigger on that.

[@msimonse]

I could read any of your screen shots or part numbers.

[@NZCUTR]

Glare and autofocus are a problem-- but if you watch on a desktop computer and freeze frame, they're all visible.

[@jackgreenstalk777]

So does the non performance motor have more reliability? I HAVE a 2014 model a 60 and it seems to be running great at 130k miles.

[@NZCUTR]

Anecdotally it seems to have less OTHER problems, but the seal issue is what it is. If you have a large rear drive unit (performance or not) it's going to have this coolant seal issue-- and I'm pretty sure the 70 or 75 was the first RWD only version to have the smaller rear motor (which is very reliable). That said, the performance versions are known to eventually crack the motor/drive unit mounts on the rear subframe, which is a significant cost replacement as well. I don't think the early regular 85/60 versions "shock" the rear mounting tabs hard enough to cause widespread cracking. The performance ones can rip them right off eventually (usually identified by loud knocking sounds and/or yawing under acceleration/braking).

[@robertcampbell6521]

EVs throw away vehicles and that's saving the planet Apparently but i fail to understand how

[@NZCUTR]

No argument from me-- the amount of waste I've seen from other Tesla owners is staggering, but the real question I usually put out there (and maybe will do a video on later) is whether or not EVs enable an unsustainable lifestyle. I think they do-- for most people-- and that's because, at least here in the US, the alternative and TRUE "planet saving" move would be to live closer to work... which no one wants to do.