Have your service center check large rear drive unit for coolant leakage before warranty expires

[maximizese]

The models with dual drive units have fewer problems because the workload is shared.

Do you know this as a fact and have any evidence or just an assumption because it sounds logical?

 

[NewbyMaybe]

Tesla tech's words. Sorry I don't have his name, rank and ss#.

 

[NewbyMaybe]

Anybody in the east rebuilding the LDU's?

 

[ajbessinger]

Do you know this as a fact and have any evidence or just an assumption because it sounds logical?

As I explained in a reply to @NewbyMaybe's comment, the reason for Dual Motor (non-performance) models having fewer issues is that the Small Drive Units that are used in them are a COMPLETELY different design than the Large Drive Units used in RWD or Performance versions of the S/X. In fact, on a Dual Motor Model S/X, the front actually does most of the work except when accelerating hard, so the work isn't really even shared all that much...

The failure mode on the LDUs has nothing to do with workload, but is rather due to a faulty design that relies on a single seal to keep the conductive, water based coolant out of the motor and HV electronics. The issue is that that seal eventually wears out, and creates an internal coolant leak, flooding the inside of the motor. The buildup of coolant creates a myriad of issues ranging from rust/corrosion buildup, isolation faults, and can even short out the circuit board on the inverter if left unchecked.

The advantage of the SDUs is that they don't used water based cooling at all for the motor (apart from a heat exchanger, and the cooling for the inverter itself, which is totally sealed off from the motor), instead they use oil for cooling. Since the oil is non-conductive, no seals are required, and the components in the motor literally just have essentially an "oil shower" directly on the components. That also means it can also cool more effectively since it cools the outside of the rotor instead of the inside (much more surface area), and doesn't rely on a heatsink effect for cooling the windings.

 

[Pcm888usa]

Can I check this thing myself? Or will Tesla notice that “someone” other than Tesla tampered with it and try to deny the warranty claim?

I am lucky (or unlucky) the coolant on my 2019 Mod3 leaked, for the 2nd time and it dripped on the garage floor both times. It was leaky hose and it corroded other components near by that needed cleaning. The two leaking are 9 months apart.

 

[Droschke]

Not sure, but maybe the seals hardening up due to a lack of cycling/movement? It's mainly just an observation I've made, not sure how accurate it is, but I work on a lot of these motors...
Most of the seals I've seen go bad at low mileage were in cars that were not driven very often (e.g., under 5k mi per year). I've even seen seals go bad within a year or two of a new motor being installed in a car, and in most of those cases, they had had less than 10k mi put on them (some even as little as 2-3k mi). On the cars that are driven regularly though, the seals seem to last longer in my experience.
There are similarities to that with seals on ICE engines too, a lot of the time cars that sit for extended periods of time develop major leaks because the rubber seals harden up, which leads to diminished sealing properties, and makes them get worn out quicker. Rubber definitely hardens over time if not cycled often (look at tires as an example). The PTFE seals in the LDU are a totally different material from rubber, but it seems like they have similar properties in that respect. Either that, or maybe the seals never got a chance to be properly broken it to mate with the sealing surface and form a tight seal.

Thanks for clarification. My curiosity was due to my original LDU developed the infamous milling noise @37k miles and Tesla replaced it with a Q version (ASY,P-TRAIN,MECH,COMPLETE,RC 1002633-00-Q). Any thoughts on the quality of this particular LDU you can share?

 

[ajbessinger]

I am lucky (or unlucky) the coolant on my 2019 Mod3 leaked, for the 2nd time and it dripped on the garage floor both times. It was leaky hose and it corroded other components near by that needed cleaning. The two leaking are 9 months apart.

That's a totally separate issue from what we are talking about here, which is an internal leak inside the drive unit due to a worn out seal. In these instances, no coolant leaks out externally, instead it "floods" the inside of the motor and will often show no warning signs until the drive unit is permanently damaged. Luckily, your Model 3 does not have a Large Drive Unit, so it doesn't suffer from this particular problem.

 

[ajbessinger]

Thanks for clarification. My curiosity was due to my original LDU developed the infamous milling noise @37k miles and Tesla replaced it with a Q version (ASY,P-TRAIN,MECH,COMPLETE,RC 1002633-00-Q). Any thoughts on the quality of this particular LDU you can share?

Q revision drive units are basically the "newest", though that's not saying much as they first started using Q's a few years ago. Based on the LDUs I've seen, not even all Q's are the same in terms little things, and some of the newest ones even have different differentials in them. It honestly kinda seems like Tesla quit documenting changes with the revision letter after Q came out....
The most important things to know about Q revision LDUs though is that they do of course have the hybrid ceramic bearings, which is a good thing (that is essentially the "permanent fix" for the milling noise issue). The downside though is that all of the Q revision motors I've seen do have the single lip coolant seal instead of a triple lip seal, which means the seal is more prone to premature failure.
Regardless of revision, mileage, or replacement date, it's important that anyone who has an LDU equipped car should keep up on regularly checking the speed sensor for any signs of coolant. I recommend checking at least once a year at a bare minimum, but the more often the better...

 

[Droschke]

Thanks for your informative response.

all of the Q revision motors I've seen do have the single lip coolant seal instead of a triple lip seal

Is it possible for you to post a side by side picture of the single vs triple seals here for visual understanding?

it's important that anyone who has an LDU equipped car should keep up on regularly checking the speed sensor for any signs of coolant. I recommend checking at least once a year at a bare minimum, but the more often the better...

This puts the Non-DIYers at a disadvantage

 

[ajbessinger]

Thanks for your informative response.



Is it possible for you to post a side by side picture of the single vs triple seals here for visual understanding?



This puts the Non-DIYers at a disadvantage

It's pretty simple to do with just basic hand tools, but if that's still outside your capabilities, any competent shop should be able to do it for you (or if you're in our area, we will do it for free at our shop). There's no need to disconnect the HV for the speed sensor check procedure, and it only takes about 10min to do (maybe a bit longer if you don't have a driver for removing the bottom cover simply because there are so many screws).

I've attached a couple pics of the different types of seals. Sorry they are a bit tough to see... It's hard to get good pictures of them while still in the housing as the center tube is in the way, and they get too mangled when removing them from the housing to be very good for demonstration purposes. The seal we use in house when rebuilding these drive units is very similar to the OE triple lip seal, though with a few small differences.

 

[Droschke]

It's pretty simple to do with just basic hand tools, but if that's still outside your capabilities, any competent shop should be able to do it for you (or if you're in our area, we will do it for free at our shop). There's no need to disconnect the HV for the speed sensor check procedure, and it only takes about 10min to do (maybe a bit longer if you don't have a driver for removing the bottom cover simply because there are so many screws).

I've attached a couple pics of the different types of seals. Sorry they are a bit tough to see... It's hard to get good pictures of them while still in the housing as the center tube is in the way, and they get too mangled when removing them from the housing to be very good for demonstration purposes. The seal we use in house when rebuilding these drive units is very similar to the OE triple lip seal, though with a few small differences.

Thanks so much for your super informative posts and being so gracious to accommodate all these questions. You have definitely helped to educate me

 

[ShaolinEV]

So non-performance Model S drive unit will be better for long term?

 

[ajbessinger]

So non-performance Model S drive unit will be better for long term?

Yes, but only if it's a Dual Motor car (70D, 85D, 90D, LR, etc.). All RWD S's on the other hand use the same motor as the Performance in the rear (only difference is Performance has a higher powered inverter).

 

[Wim_V]

Do you sell the tripple lip seal, or can you share a source? I can only find the low quality Chinese seal form Ceimin.

 

[howardc64]

13 MS85. 3rd DU (revQ) on 3/2017 at 40k miles. Now 72k miles. Had droning whine at 30mph initially. Getting louder each year. Loudness is drowned out by wind at higher speeds.

Just pulled speed sensor. Coolant present (see attached pics) Last pic is capture of youtube video on post #3 on degree of leak and corrosion.

Made annual request to evaluate noise with SC manager, had 2 mobile techs drive and evaluation. Was always told within HQ mandated noise level (presumably to reduce field DU replacements) have 8 year unlimited mile warranty. No need to worry.

Now the DU nursed beyond warranty. Long time SC manager's email bounces. Going through Tesla's service app but have always encountered new college grads quoting HQ policy. I'm probably stuck with this one.

2014 MS DU's are out of warranty during current year so best to get someone to pull the speed sensor for coolant leak inspection. 2015s DU out of warranty starts in 4 months.

 

[Droschke]

Are LDU's still in production?

What would you get from Tesla if you paying out of pocket? Only a re-manufactured one with the same bad design or are there newer LDU's with the better design that would fit your car?

I'm on the second LDU, which was replaced in 2017 @37k miles with a new Q version. I've only 10k miles on this Q version. I do hear a bit of faint noise (not the infamous milling noise) at low speed, especially with the windows down, but not sure if that's normal or not. The noise sounds like a ICE manual transmission car in higher gear going downhill when you take your foot off the accelerator pedal.

 

[howardc64]

Are LDU's still in production?

What would you get from Tesla if you paying out of pocket? Only a re-manufactured one with the same bad design or are there newer LDU's with the better design that would fit your car?

Will not use Tesla if out of pocket. No confidence in HQ design and after HQ neutered SC's capabilities. 2 separate service experiences causing more damage to the car (steering rack bolt recall causing rack to pop, MCU1 screen bubbling after park in sun for 3 days without doing any work)

Will either use an independent (probably need to ship car or remove/ship DU) or attempt myself (have high DIY capability but job looks quite challenging - even simple job of lifting the car on this car is more involved than most other cars)

I'm on the second LDU, which was replaced in 2017 @37k miles with a new Q version. I've only 10k miles on this Q version. I do hear a bit of faint noise (not the infamous milling noise) at low speed, especially with the windows down, but not sure if that's normal or not. The noise sounds like a ICE manual transmission car in higher gear going downhill when you take your foot off the accelerator pedal.

Downhill engine braking noise is a good description of this noise. Its the correct frequency to what I have since day one on RevQ. I'm guessing your first DU had no such sound? (my prior 2 DUs didn't have)

Here are more sound characteristics

- Got louder each year and seems louder with arrival of warmer weather.

- My noise is more prominent with windows closed (no wind noise) as it vibrates through the cabin. I have no rear shelf. Louder with some of the carpeting in rear is pulled off (impossible to reinstall plastic carpeting clips on the 13 but unnecessary anyways) since thats where the DU is.

- Noise is really based on load. Will come on at around 30kW load initially. The reason downhill is more prominent is due to lower speed (lower wind noise) with regen load. Same 30kw load under acceleration will also produce the noise but quickly accelerates the car faster with more wind noise to drown out the DU noise.

- I think an easy way to demo the noise is to have tires off the ground and spin the motor (remove the wind noise) My impression is HQ's policies basically stops HC from doing much DU noise investigation.

- Maybe the noise is due to RevQ's ceramic rotor bearings? Don't know without more statistics. I seem to have developed a new noise that comes in at all speeds this year. Perhaps the coolant leak has damaged more of the bearing grease. Don't know. Here is what the rotor's bearing grease look like after coolant seal leak. Its an Rav4 EV with Tesla's LDU and recently completed DIY seal replacement/rotor bearing regrease. Poster has full video of the rebuild. Quite involved.

 

[ajbessinger]

Are LDU's still in production?

What would you get from Tesla if you paying out of pocket? Only a re-manufactured one with the same bad design or are there newer LDU's with the better design that would fit your car?

I'm on the second LDU, which was replaced in 2017 @37k miles with a new Q version. I've only 10k miles on this Q version. I do hear a bit of faint noise (not the infamous milling noise) at low speed, especially with the windows down, but not sure if that's normal or not. The noise sounds like a ICE manual transmission car in higher gear going downhill when you take your foot off the accelerator pedal.

As far as I know, pretty much all LDUs put into cars anymore are remanufactured (I've heard rumors they quit making them, but can't confirm). All of the drive units since ~2015 use the same inferior single lip seal that is more likely to wear out prematurely. I've pulled apart a few LDUs that are less than 2 years old with serial numbers past 1M. Those ones have the newer style differential (6 spider gears instead of 4), but still use the same s**tty single lip seal. By the way, the revision letters end at Q, even though there are definitely some small changes in the motors made since 2017 (like the diffs), why they haven't kept track with further revision letters, I don't know...

If you've really only done 10k mi in 5 years, you should definitely check your speed sensor for signs of coolant... I've noticed that cars that don't get driven much tend to be more likely to have early failures than cars that get drive more often. Can't necessarily say that that is always 100% true, but it's a trend that I have noticed...

 

[Droschke]

Will not use Tesla if out of pocket. No confidence in HQ design and after HQ neutered SC's capabilities. 2 separate service experiences causing more damage to the car (steering rack bolt recall causing rack to pop, MCU1 screen bubbling after park in sun for 3 days without doing any work)

Will either use an independent (probably need to ship car or remove/ship DU) or attempt myself (have high DIY capability but job looks quite challenging - even simple job of lifting the car on this car is more involved than most other cars)



Downhill engine braking noise is a good description of this noise. Its the correct frequency to what I have since day one on RevQ. I'm guessing your first DU had no such sound? (my prior 2 DUs didn't have)

Here are more sound characteristics

- Got louder each year and seems louder with arrival of warmer weather.

- My noise is more prominent with windows closed (no wind noise) as it vibrates through the cabin. I have no rear shelf. Louder with some of the carpeting in rear is pulled off (impossible to reinstall plastic carpeting clips on the 13 but unnecessary anyways) since thats where the DU is.

- Noise is really based on load. Will come on at around 30kW load initially. The reason downhill is more prominent is due to lower speed (lower wind noise) with regen load. Same 30kw load under acceleration will also produce the noise but quickly accelerates the car faster with more wind noise to drown out the DU noise.

- I think an easy way to demo the noise is to have tires off the ground and spin the motor (remove the wind noise) My impression is HQ's policies basically stops HC from doing much DU noise investigation.

- Maybe the noise is due to RevQ's ceramic rotor bearings? Don't know without more statistics. I seem to have developed a new noise that comes in at all speeds this year. Perhaps the coolant leak has damaged more of the bearing grease. Don't know. Here is what the rotor's bearing grease look like after coolant seal leak. Its an Rav4 EV with Tesla's LDU and recently completed DIY seal replacement/rotor bearing regrease. Poster has full video of the rebuild. Quite involved.

My original LDU (manufactured in 2015) had both “engine braking” and the milling noise. I believe I noticed the engine braking noise first, which I ignored till the milling noise started and got worse over time till the LDU was replaced in 2017 @37k miles with a new Q version. Having only 10k miles on this Q version, which is not a remanufactured one, I was surprised to hear engine braking noise again the other day, but I do not hear it all the time, which might be due to the windows up, the road noise and/or having the parcel shelf in my car. It’s beyond my comprehension as to why Tesla has never addressed the LDU issues and keeps installing the same problematic units in our cars. Oh, I just remembered … What happened to those 1 million miles DU’s ?

 

[ucmndd]

Are LDU's still in production?

I’d strongly suspect not given they aren’t used in any new cars any more. Reman from here on out…