Model S Technical / Mechanical Issues

[Luv2preech]

The seal we use is custom built for us to our specifications. As far as I know, there is no source for a suitable off the shelf replacement, trust me, I searched for a long time to find one.

The hybrid ceramic bearings for the rotor are a special order item that comes from Germany, and retail for about ~$400 ea. There are also two other bearings in the gearbox that we replace as well whenever we have a motor torn apart.

If you want to call our shop tomorrow, we may be able to sell you a set of new bearings and a seal (that's up to my boss Tony though, and he might not want to do that). I do know that if you wanted to ship the car, or just the drive unit itself to our shop, we'd be happy to do a full rebuild for you.

There are quite a few specialized and expensive tools required to tear down a drive unit properly without damaging it, and a fair bit of expertise that goes along with doing so as well.

since you say that you are having issues with the car, it would be best to have the whole thing torn down and closely examined in order to repvent a catastrophic failure. There are a multitude of other issues to check for while the motor is out of the car, besides just the seal, so its best to tear the whole thing down to make sure everything is in good order. We have rebuild dozens of these drive units, and as far as I know we are the only shop in the world that is doing so, so I think its pretty safe to say we are the world wide experts.

If you want to get in touch here's the contact info for our shop:
QC Charge
Vista California, USA
+1 (760) 798-0342
+1 (844) EV-Parts
[email protected]

 

[Luv2preech]

Thank you!
I will call.

 

[ajbessinger]

Just got the rear drive unit rebuilt in this 2014 Model S last week! While the coolant seal on this one was actually in pretty decent shape, the bearings were definitely very noisy. Thanks to a new set of hybrid ceramic bearings the car is now nearly silent!

Also, for any Model S (as well as Rav4 EV and Mercedes B-Class) owner in the SF Bay area, our company is having a "speed sensor party" on March 20-21. For $25 we will remove your rotor speed sensor to check for internal coolant leakage.

You can sign up for a time slot at this link:
Speed Sensor PARTY - San Jose, California USA - March 20-21, 2021

 

[Luv2preech]

I am the recipient of the ‘new’ bearings upgrade as stated above. (Salvage title, so no warranty) Quick and professionally done, and, very pleased with the results. I HIGHLY recommend Tony and Alex at QC Charge. What a difference, like a new car again!!

 

[ajbessinger]

Howdy folks, sit down and gather round, cause I've got another fun story today from the land leaking coolant seals.

Today I pulled out this drive unit from a car that would roll, but wouldn't run. Combined with the fact that the coolant was quite low (and it clearly hadn't leaked onto the ground), I knew this was likely a situation of coolant getting into the motor, and eventually migrating all the way through to the inverter. As you can imagine, coolant and electronics don't got together very well, and the coolant (or rather mix of rust and coolant) destroyed at least one of the circuit boards, and probably a significant amount of the wiring on the inverter.

I've seen this happen on a few occasions, but it typically only happens on earlier motors (newer motors tend to seize up before coolant can ever get all the way to the inverter cavity). What's really special about this one is that once I started pulling it apart, I realized this was one of the worst looking cases of coolant caused corrosion that I have ever seen in a motor, so I thought I'd take a few pics to share here. I'm honestly quite surprised that this car was easily able to roll.

Let's start from the beginning. Here's what the speed sensor looked like when I pulled it out. Things already aren't looking good...

And here's the hole where the speed sensor goes in. I don't think I've ever seen that much debris packed in before.

Pulled the seal assembly off, and found more rust/debris. Keep in mind, almost all of this somehow made it's way through the rotor bearing, or through that little tiny hole (maybe about 1/10th of an inch in diameter) just to the right of the reluctor wheel.

Here's the failed seal itself.

At this point, I still haven't removed the rotor end cap yet. That comes after I remove the inverter, here's what I found when I removed the inverter cover, a mix of rusty coolant sludge.

The inverter itself.

Some corrosion on the connectors to the main driver board.

And some more sludge on one of the gate drive boards.

As you can see, this looks like a total disaster....and I can assure you, it is. This inverter is completely toast, beyond repair. We've tried repairing these before, but have never been able to do it successfully, so it will just need the whole thing to be replaced. Luckily, we happen to have one or two of them sitting on the shelf.

Tomorrow I'm going to start tearing into the motor itself, hopefully at least it is still rebuildable...

 

[ajbessinger]

An update to yesterday's motor story. This morning, I pulled out the rotor and found some pretty serious corrosion, and the "front" rotor bearing is one of the worst I've ever seen. The bearing seals and plastic bearing cage had pretty much disintegrated. Luckily, the rotor splines are in good shape, and the corrosion was pretty easily cleaned up.

Quite a rusty rotor, but not the worst I've seen.

The inside of the motor. Again, not the best, but certainly not the worst either.

This bearing on the other hand....does not look good.

Managed to get the rotor cleaned up, looks almost as good as new!

And the inside of the motor as well.

Now it just needs new bearings, a coolant seal, and a good inverter installed, and it should be back up and running!

 

[JRP3]

I wonder if it's worth using phosphoric acid wash to remove any remaining rust particles and create a passive iron phosphate surface. I often use that on bare steel and even without paint it will protect the metal for a long time if not directly exposed to the elements.

 

[2101Guy]

I love ajbessingers posts. He should receive some sort of honorary VIP status on here or something, for his contributions.

Hey AJbessinger: ballpark figure of what that bill is going to run? Just a ballpark if you can. Out of curiosity. And did I understand correctly that this issue is isolated to the large rear drive units?

 

[ajbessinger]

I love ajbessingers posts. He should receive some sort of honorary VIP status on here or something, for his contributions.

Hey AJbessinger: ballpark figure of what that bill is going to run? Just a ballpark if you can. Out of curiosity. And did I understand correctly that this issue is isolated to the large rear drive units?

Thanks for the compliment! This repair (full motor rebuild) costs ~$4,000 at our shop. In the case of that particular drive unit above, it would cost a bit more as we had to replace the inverter assembly on it as well since it had been destroyed by that goopy coolant mess. You are correct that these issues are pretty much only associated with the large drive units (LDU).

When we do a teardown like this, the first thing we do is inspect the motor for any sort of damage. There are a few common ones to look out for, bearings, splines, inverter, abnormal gear wear, etc. Then, we clean everything up, remove the bearings, and old rotor seal. Then we replace the failed seal with a custom made triple lip PTFE seal, as well as replace the bearings with the upgraded hybrid ceramic ones (they are just like the ones in the newer "Q" drive units, and they cost us about $300 each!). We will also replace the axle seals too, as they are usually original and leaking. Lastly of course, the gearbox gets new oil, and then goes back into the car for testing. Once the car has been test driven, and we are satisfied with the result, it's ready for pickup!

 

[ajbessinger]

I wonder if it's worth using phosphoric acid wash to remove any remaining rust particles and create a passive iron phosphate surface. I often use that on bare steel and even without paint it will protect the metal for a long time if not directly exposed to the elements.

I'm not sure... Technically, the inside of the motor shouldn't be exposed to any kind of elements period (so normally it should be fine. I'd also be worried about what the acid would do to the insulation material on the windings.
It also seems that on the later drive units (that tend to have worse issues with rust and siezing), there is less chance of coolant getting to the inverter before the owner notices a problem, or the car will no longer move. This can usually be repaired. Earlier drive units actually do have some sort of coating on the rotor, but because the rotor doesn't rust/seize up, the inverter is often the first thing to go, and that can't be repaired once coolant gets to it.
View media item 122286

 

[LTUAE42]

Cannot edit anymore but it is door handle RF, door handle RR and window motor RF and RR are all connected together with the same LIN bus.

Latham Tesla service station figured out the problem today and fixed it. The door handle passenger side shorted and blew the fuse to the door control module killing power to both passenger doors. They replaced the the door handle and fuse and final price with diagnostics was 472.00 PS after I picked up the car my Chip went bad and my touch screen stop working right. I had no music or heat control. I called them and they had me return the car for the recall with the chip. I am back in the loaner Tesla and was told sometime next week they will have my chip replaced . Goodtimes

 

[LTUAE42]

Help for no reason my passenger side of the car went dead yesterday. The doors wont present or open from the outside and the windows will not function. The side mirror is also not functioning with no door lights too. Tesla suggested it could be the ground stud. I pulled the frunk and the ground stud looks fine. The headlights work too. The only thing dead is from the passenger door to the back door on the passenger side. When I open the door from the inside the window drops like its suppose to and goes back up when the door is shut so there is power . I am so confused what it could be. I looked at the wiring going to the door and I dont see any damage from mice etc. any idea ?? i cant afford an expensive diagnostics and the first opening at Tesla is the end of the month and I drive my car every day. Thanks for any help.

UPDATE Latham Tesla service station figured out the problem today and fixed it. The door handle passenger side shorted and blew the fuse to the door control module killing power to both passenger doors. They replaced the the door handle and fuse and final price with diagnostics was 472.00 PS after I picked up the car my Chip went bad and my touch screen stop working right. I had no music or heat control. I called them and they had me return the car for the recall with the chip. I am back in the loaner Tesla and was told sometime next week they will have my chip replaced . Goodtimes

 

[ajbessinger]

Here's an example of another issue that can be associated with the Large Drive Units. I just pulled this one apart today as the owner their speed sensor and saw coolant, in addition to the fact that the motor was starting to make a bit of bearing noise at 35k original miles.

The coolant seal must have just barely started to leak, as the inside of this motor was exceptionally clean, in fact, it looked almost brand new! However, the splines are not in good shape... As you can see, there is actually not very much left of them at all, and it probably would not have lasted another 10-15k mi before they let go completely. Unfortunately, this is an issue that can't be fixed (short of replacing the rotor and the entire gearbox), so the whole motor will have to be replaced. It's really a shame since this was such a clean/low mileage drive unit.

I've seen this issue a handful of times on earlier production drive units. For some reason, the grease gets cooked out, and then the splines just get the crap beat out of them. Eventually, they get to a point where the splines strip out completely, and the motor will spin, but the car will not move.

 

[JRP3]

Might be able to repair the splines. Build up the shaft by welding or metal flame spray, turn it true on a lathe and then cut new splines. A good machine shop should be able to do it.

 

[Feathermerchan]

Or just weld the gear on to it since it's a one time fix. Wouldn't e possible if there has to be a seal on it.

 

[ajbessinger]

Might be able to repair the splines. Build up the shaft by welding or metal flame spray, turn it true on a lathe and then cut new splines. A good machine shop should be able to do it.

It would probably be possible to repair the shaft itself, or just make a whole new shaft, since it appears to be pressed into the rotor and held in place with a snap ring. The gear is another issue entirely, and I don't think it could be fixed short of replacing the whole gear, which could cause noise/wear issues in the gearbox if not matched with the other gears perfectly. So short of replacing all 3 gears, and repairing/replacing the rotor, I don't think it would be feasible, and at that point, its approaching the point where there's a lot of extra work and parts involved, so its simpler and cheaper to just use another motor core to rebuild (of which we have several sitting on the shelves of our shop).

Or just weld the gear on to it since it's a one time fix. Wouldn't e possible if there has to be a seal on it.

The gear and rotor can't be welded together as the are inserted on different sides of the case, and there is a seal that goes around the end of the gear where it meets the rotor.

 

[TechOps]

Just got the rear drive unit rebuilt in this 2014 Model S last week! While the coolant seal on this one was actually in pretty decent shape, the bearings were definitely very noisy. Thanks to a new set of hybrid ceramic bearings the car is now nearly silent!

View attachment 632675

Also, for any Model S (as well as Rav4 EV and Mercedes B-Class) owner in the SF Bay area, our company is having a "speed sensor party" on March 20-21. For $25 we will remove your rotor speed sensor to check for internal coolant leakage.

You can sign up for a time slot at this link:
Speed Sensor PARTY - San Jose, California USA - March 20-21, 2021

Question on eligible vehicles -- It says 2015-newer Model S/X with Insane/Ludicrous. I have a late 2017 Model S 75, which has the more powerful ("uncorked") rear drive unit -- is that a different LDU than the insane/ludicrous ones? How can I check my exact drive unit model against the ones that are vulnerable to this coolant issue?

 

[ajbessinger]

Question on eligible vehicles -- It says 2015-newer Model S/X with Insane/Ludicrous. I have a late 2017 Model S 75, which has the more powerful ("uncorked") rear drive unit -- is that a different LDU than the insane/ludicrous ones? How can I check my exact drive unit model against the ones that are vulnerable to this coolant issue?

It's a RWD S 75 correct, not a 75D? If so, that's actually a fairly rare car, but as far as I know, it would have a Large Drive Unit, as all RWD S's do .

The best (and only) way to really check for internal coolant leakage is to remove the rotor speed sensor, which is located on the left side of the motor, near the coolant inlet tube. If you see any liquid on the sensor, or in the hole it goes in, then that indicates your rotor coolant seal is leaking.

To remove the sensor, you'll need to first remove the plastic splash shield from under the rear of the car. Then, locate the speed sensor (see pic below), and remove the small 4 pin connector that is plugged into it. This can be a little tricky, as it's a tight space to work in. Then, simply remove the single bolt that holds it in using a 10mm wrench.

Here's where the speed sensor is located (you can just see the 10mm bolt that holds it in in this pic).

Here's what the speed sensor looks like when removed. If you see liquid on it like in the pic, then you have a problem. Also make sure to check inside the hole where the sensor goes to check for liquid there as well.

 

[hpartsch]

It's a RWD S 75 correct, not a 75D? If so, that's actually a fairly rare car, but as far as I know, it would have a Large Drive Unit, as all RWD S's do .

The best (and only) way to really check for internal coolant leakage is to remove the rotor speed sensor, which is located on the left side of the motor, near the coolant inlet tube. If you see any liquid on the sensor, or in the hole it goes in, then that indicates your rotor coolant seal is leaking.

To remove the sensor, you'll need to first remove the plastic splash shield from under the rear of the car. Then, locate the speed sensor (see pic below), and remove the small 4 pin connector that is plugged into it. This can be a little tricky, as it's a tight space to work in. Then, simply remove the single bolt that holds it in using a 10mm wrench.

Here's where the speed sensor is located (you can just see the 10mm bolt that holds it in in this pic).
View attachment 635860

Here's what the speed sensor looks like when removed. If you see liquid on it like in the pic, then you have a problem. Also make sure to check inside the hole where the sensor goes to check for liquid there as well.
View attachment 635862

Hi! Is there any way you can do a quick video next time you remove the splash shield and sensor -- I'm a visual person -- youtube videos helped me do a ton - but so far i've not found a video on this process? I think I have a general idea what to do but don't feel confident yet.

 

[hpartsch]

The seal we use is custom built for us to our specifications. As far as I know, there is no source for a suitable off the shelf replacement, trust me, I searched for a long time to find one.

The hybrid ceramic bearings for the rotor are a special order item that comes from Germany, and retail for about ~$400 ea. There are also two other bearings in the gearbox that we replace as well whenever we have a motor torn apart.

If you want to call our shop tomorrow, we may be able to sell you a set of new bearings and a seal (that's up to my boss Tony though, and he might not want to do that). I do know that if you wanted to ship the car, or just the drive unit itself to our shop, we'd be happy to do a full rebuild for you.

There are quite a few specialized and expensive tools required to tear down a drive unit properly without damaging it, and a fair bit of expertise that goes along with doing so as well.

since you say that you are having issues with the car, it would be best to have the whole thing torn down and closely examined in order to repvent a catastrophic failure. There are a multitude of other issues to check for while the motor is out of the car, besides just the seal, so its best to tear the whole thing down to make sure everything is in good order. We have rebuild dozens of these drive units, and as far as I know we are the only shop in the world that is doing so, so I think its pretty safe to say we are the world wide experts.

If you want to get in touch here's the contact info for our shop:
QC Charge
Vista California, USA
+1 (760) 798-0342
+1 (844) EV-Parts
[email protected]

Also, another question. If I were to take it apart and find liquid while my car is under warranty... Will tesla do anything or are they refusing until catastrophic failure? Not sure if you know this question, but figured it's worth a shot. I got 6 more months left on my 2013.