2013 P85 Rear Drive Unit Rebuild - Looking for Mechanic

[howardc64]

@howardc64 can one remove the speed sensor fully without disconnecting the cable? how much slack is on the cable one the sensor is out? minimal or enough to see inside the orifice? I'd rather not break the clip and if i can take it out of the housing altogether, sounds like that is the way to go.

Getting under this car is not so easy. Am a descent auto DIYer but dreaded safely jacking it up to check the speed sensor for awhile. Here is a complete write up.

Sweep the floor

If not using a lift, will likely be laying on the floor. Head will rest on ground often... hopefully not on uncomfortable pebbles/rocks

Raise the car

Drive up shallow ramps is my favorite method with tires raise about 5+ inches. Will provide enough clearance but not all that comfortable

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Necessary tools

Gather these to avoid multiple trips crawling out from under the rear end.

• Electric driver with 10mm socket is a great help with a bunch of 10mm to remove
• Plastic clip prying tool (or thin + wider flat head screwdriver)
• work light(s) standing ones are bright but get in the way often as you work on both sides. A light that doesn't roll is helpful working on the floor.
• 10mm wrench to loosen/tighten speed sensor bolt
• Silicone lubricant - finger apply a drop on the speed sensor o-ring before re-install (probably no necessary)
• thin and thicker flat head to wiggle / leverage out the speed sensor
• Card board to lay on

Type of bolt (10mm head), screw (10mm head), and clip shown in the pic



Clearance



Mid Aero Shield Removal

Remove all 4 strakes. Tip, leave middle screw/bolt in last and install it first on reinstall on the strakes so with 1 screw, strake will hang leveled rather an dangle one end on the floor without much space.

Remove all bolts, screws and plastic clips per https://teslamotorsclub.com/tmc/attachments/rear_undertray_and_diffuser-mi00-jpg.894912/ Note diagram is annotated with fewer bolt/screw installs for quicker subsequent removal

Speed Sensor Location

On the drive unit facing the driver side tire.

Remove Speed Sensor

• No need to remove connector (I worry it could break given amount of force required)
• Remove 10mm bolt
• Use thin followed by thicker flat head to wiggle/lever (in multiple spots) out the speed sensor. Avoid going in too deep and damage the o-ring
• Can pull speed sensor all the way out of the hole

If coolant seal is leaking, it will show droplets on the speed sensor. No need to look inside the hole.

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

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?

teslamotorsclub.com

Can use a drop of silicone lubricant (or any rubber safe lubricant I suppose) around the o-ring to reinstall. Probably not necessary.

LDU Revision

Mine had a sticker on bottom. To decode it, see here

Tesla LDU - Revisions

Many Revisions Tesla has had many version of the LDU and most cars were getting LDUs replaces every few 10k miles with regularity. My 2013 MS has had the original (don't know Rev) to Rev K and then onto Rev Q all in 40k miles. There are some differences between all these Revs. Following is not a

sites.google.com

 

[Alabaster]

Amazing. Thanks @howardc64 ! Will be doing this on the upcoming weekend (pending rain). Anxious to see what I find. Keep you posted.

 

[howardc64]

One more note

Reinstalling Mid Aero Shield

Shield will flop in the middle after threading in first couple of bolts. This will likely tug on the bolts towards front of the car as they are the hardest to reach while crawling under the car. Furthermore, you will in a poor position to judge its angle. Easy to cross thread (don't ask me how I know haha) So thread all the bolts most of the way by hand before resorting to that handy electric screw driver Not necessary for the screws.

Oh and don't remove anything with orange covers.. deadly HV. Orange cables are HV cables and obviously insulated but there is no need to get near them anyways for speed sensor check. Maybe a good idea to remove metal jewelry anytime near HV electronics. If you have coolant drops on sensor, there is a way to confirm coolant in inverter externally but requires getting closer to dangerous and deadly HV. Perhaps just stop using the car and seek a rebuild.

Tesla LDU - Failure Testing

Table of contents

sites.google.com

But until can confirm your noise is from the LDU, LDU rebuild may not solve that problem.

 

[Alabaster]

@howardc64 so, I did a full power down today and let the car sit. Upon driving it for bout 20 minutes at varying speeds (highway, etc), I've noticed that the regenerative braking seems almost non-existent, both set on standard and on low. I wonder if this noise I'm hearing is something related. Where I park at work is on a small include so I always apply the parking brake. Perhaps all the brakes slides need lubricated. Will have to do some more research on the Regen braking.

 

[howardc64]

Regen is severely limited when battery is cold. Regen produces a lot of power and I guess can degrade cold batteries significantly. Read my post here and follow-on discussions

cell warm up analysis

Sorting out coolant heater behavior with a fellow 2013 MS owner with gen1 DCDC in these winter months. Used scanmytesla to record 3 trips. Here is the conclusion and data Car is no hurry to warm up the cell. Regen is limited for quite while until avg cell temp reach ~18.4C which takes more than...

teslamotorsclub.com

Do you see the orange regen line? It can take like an hour of driving to get full regen capability. Coolant need to transfer heat from source to warm the batteries.

 

[Alabaster]

Regen is severely limited when battery is cold. Regen produces a lot of power and I guess can degrade cold batteries significantly. Read my post here and follow-on discussions

cell warm up analysis

Sorting out coolant heater behavior with a fellow 2013 MS owner with gen1 DCDC in these winter months. Used scanmytesla to record 3 trips. Here is the conclusion and data Car is no hurry to warm up the cell. Regen is limited for quite while until avg cell temp reach ~18.4C which takes more than...

teslamotorsclub.com

Do you see the orange regen line? It can take like an hour of driving to get full regen capability. Coolant need to transfer heat from source to warm the batteries.

i think thta is exactly what happened. After stopping to get kiddos and hoping back in the car, reg braking was back up and running.

I am still wondering if its a brake pad rub. Borrowing some heavy duty ramps this weekend to investigate the speed sensor.

 

[geordi]

From what you describe of the sound.... It could also be as simple as a wheel bearing. The S has 4 of them that are very similar.

 

[Alabaster]

From what you describe of the sound.... It could also be as simple as a wheel bearing. The S has 4 of them that are very similar.

that is a possibility i had not considered. I would think if it were a wheel bearing that it would be consistent when the wheels are in motion.

 

[geordi]

"Consistent" maybe.... But also speed dependent. I just had one that only started howling above 40mph, would track with road speed but was always there. Thought it was the driver's front, turned out to be the passenger side.

Could feel a "gritty" feel in the bearing when turned in your hand after removal.

 

[Alabaster]

So.... I was able to pull the speed sensor today. neighbors had Rhino ramps rated to 12k pounds. put car in very high mode and back right up on the ramps. couldn't add jackstands to rear of car as ramps were too long. added wheel chocks to both front tires. all said and done, it wasn't too bad a job. everything on the rear end of the car looks original. there was some writing on something there but i have no idea what it would have been.

it was wet as you can see in the photos, along with a far amount of sand. not sure why there would be sand in it unless the o-ring failed. Leak does unfortunately verify that something (bad) is going on with the DU.... the passenger side of the DU appeared to have some oil or similar substance on it. any ideas why that would be wet?

@howardc64

 

[NewbyMaybe]

If water or coolant is inside then the oil is forced out?

 

[howardc64]

So.... I was able to pull the speed sensor today. neighbors had Rhino ramps rated to 12k pounds. put car in very high mode and back right up on the ramps. couldn't add jackstands to rear of car as ramps were too long. added wheel chocks to both front tires. all said and done, it wasn't too bad a job. everything on the rear end of the car looks original. there was some writing on something there but i have no idea what it would have been.

Nice, and backed up even. I'm afraid of steep ramps haha. Bad experience with metal ones but plastic is probably much better. Grippier.

it was wet as you can see in the photos, along with a far amount of sand. not sure why there would be sand in it unless the o-ring failed. Leak does unfortunately verify that something (bad) is going on with the DU.... the passenger side of the DU appeared to have some oil or similar substance on it. any ideas why that would be wet?

@howardc64

If water or coolant is inside then the oil is forced out?

Sensor has some wetness. Not sure degree of wetness tells anything about interior damage level. Here is my sensor pic. I guess the oily residue has to be coolant mixed bearing grease I suppose. I've wondered if remanufacturing rebuilder install the seals with grease (which I think is a no no) for the harder to install PTFE material seals.



I don't think the sensor o-ring is compromised. Bearing grease + coolant seems to produce white colored sandy feeling material. Pics here

Tesla Large Drive Unit (LDU) Motor Teardown and maintenance - Page 8 - openinverter forum

The passenger side orange cover that says B+ B- shows leaking something as well from the bottom of black connector (low spot). Thats where the inverter is. This cartoon diagram shows how the LDU is laid out

Out of Warranty Drive Unit Replacement and Cost

Sorry - I thought I had said it (I intended to) but that didn't translate through the keyboard. The quote was for a remanufactured P-Train Reman Sport Large 1025598-00-T and another $650 for the harness from the inverter to the rear junction box. I repeat though: The car is driving perfectly...

teslamotorsclub.com

This is worrisome. Mine was perfectly clean externally. Yours has either been leaking for quite awhile or coolant pooled high enough to exit. It doesn't take much coolant puddle inside to wick up the wiring harness at the bottom of the inverter (like 1/16" clearance from bottom of the cylinder case) and corrode the connector contacts and disable its communications. Car could strand you soon and may cause more damage to the inverter. Or it could drive for awhile.. don't really know. Mine was discovered at much earlier leak stage. Here is what my inverter chamber looked like

DIY Tesla Drive Unit Repair

Check the youtube channel I started about DIY repair of the Tesla Large Drive Unit (DU). This may benefit those who like to fix their car themselves, epecially if it's out of warranty. Here is the link: https://youtube.com/channel/UCIHg1trfQQTYIA88w-ZcCdw Background: The DU in my 2012 Toyota...

teslamotorsclub.com

The wetness towards the back of the inverter cover is more mysterious. Again, mine was completely clean outside so didn't encounter before. The circumference seam at the end of the inverter casing might not be water tight and another coolant exit path. If so, it suggest you have quite a bit of coolant that made its way into the inverter housing and "luckily" has been leaking out and perhaps minimized pooling so your inverter harness has not yet corrode to the point of failed communication.

Finally, your rotation sound from the rear end. Coolant damaged LDU could be the cause but there are other possibilities as previously noted. The motor's rotor and stator could have rust build up to the point of making contact. The rotor bearings could be completely trashed. Saw a posted by @ajbessinger at QC Charge that had a destroyed ball bearing cage! Don't know if that LDU was running but can't imagine it'd be quiet if was running.

Anyway, unfortunately bad diagnoses If you to stop driving, also don't want to leave it idle for months and months. I've seen 2 custom EV car builders source salvaged LDUs that has been idled for awhile. The motor rotor's shaft is not stainless steel so it will corrode with coolant just sitting idle for awhile (not sure how long) Once that shaft corrodes and pits, then it needs to get repaired requiring machinist capabilities (I've seen people with corroded/pitted shaft struggle with rebuild. Putting a new seal on won't seal)

One more picture request if you still have the mid aero shield off, take a pic of the sticker to the driver side of middle of LDU. It will indicate your rev #, reman, original manufacturing date etc.

 

[Alabaster]

@howardc64 well, that is not a good report at all! I've had the car since last May and probably should have pulled the mid shield area cover to inspect this before I bought it (although, at that point, i had never heard of a speed sensor).

There is a shop in Dayton Ohio that I am going to call to see if they service LDUs. As there is a Tesla SC there as well perhaps there is some overlap in services offered. Someone else also mentioned a shop in New Hampshire. May have to bit the bullet and get a local SC to install a rebuilt LDU or sell it.

here is the LDU sticker on the bottom driver side (i looked for access to the top of the LDU like you mentioned but that was a no-go. Guessing original based on the suspension parts i replaced on the front end and the seemingly original suspension on rear end.

 

[howardc64]

@howardc64 well, that is not a good report at all! I've had the car since last May and probably should have pulled the mid shield area cover to inspect this before I bought it (although, at that point, i had never heard of a speed sensor).

Yeah, I see a lot of > 100k mile premium used car crowd buying this. They are accustomed to buying highly depreciated German cars and can DIY maintain at reasonable cost. This is how German cars get its 3rd life (first life = lease, 2nd life is 4 year after lease, 3rd life is > 100k mile DIYers). But Tesla is a major disabler with broadly inaccessible service info, parts and tools. Basically no parts on the LDU (and the battery) is for sale so all rebuilder scramble to develop parts sourcing. This drastically reduces rebuilder #s.

There is a shop in Dayton Ohio that I am going to call to see if they service LDUs. As there is a Tesla SC there as well perhaps there is some overlap in services offered. Someone else also mentioned a shop in New Hampshire. May have to bit the bullet and get a local SC to install a rebuilt LDU or sell it.

If they've never done it but maybe willing to try (probably without warranties) and taking longer (just from sourcing and potentially encountering more difficult unknowns) They probably even have to study the rebuild procedures before starting. This cost time which would be expensive if they billed you for all of it so % has to be investment on their end. I can share with them whats involved and potential difficulties once LDU is opened up. Encountering difficulty = delay. Anyway, you'd have to be okay with this if a garage takes it on.

Anyhow, look for a good indy by reputation. If a non EV experienced shop, they probably have to tool up on regulation complaint HV tools/procedures to protect their business.

Also an Indy closer to bigger metros will have bigger aftermarket market footprint. I think Chicago is the big market in midwest by volume in the early days and those cars are off Tesla's 8 year drivetrain warranty now. Probably still the biggest market in the midwest.

here is the LDU sticker on the bottom driver side (i looked for access to the top of the LDU like you mentioned but that was a no-go. Guessing original based on the suspension parts i replaced on the front end and the seemingly original suspension on rear end.

View attachment 896038

RMN = Remanufactured
-P = Rev P. Rev R is ~ 2017 so this is installed probably just before
T14 = original manufacturing date = 2014

Def not original

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And just a reminder, nothing says LDU is source of your rear end noise so while this leak is going to cost $$, it may not resolve rear end noise unless the cause is analyzed.

 

[Alabaster]

RMN = Remanufactured
-P = Rev P. Rev R is ~ 2017 so this is installed probably just before
T14 = original manufacturing date = 2014

Def not original

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main battery was replaced in 2017, and so it would appear the LDU was replaced in 2014. Appreciate all the valuable informative info you are providing!

 

[howardc64]

Oops sorry, Rev Q was in ~2017 and Rev letters keep increasing. Anyway, a guess is your Rev P was probably installed prior to or close to 2017.

 

[Andychesh51]

Rebuild cost likely depends on what failed. Could be rusty rotor/stator or trashed rotor bearing causing reluctor wheel contact. All consequences of a coolant seal leak. Pull the speed sensor and check for leak (not easy to raise the rear of this car). If coolant leak caused and LDU making noise, I'd stop driving to avoid frying your inverter (coolant eventually reach inverter and damage it).

If sound is from gears. worn rotor spline etc... Then probably gets more expensive needing to salvage for those parts.

Did a full LDU rebuild DIY website with procedures and common parts sourcing info. If you know anyone someone who can drop the subframe and pull the LDU (quite challenging if no lift and lift table). Rebuild is not too bad beyond that. PM me for guidance if you locate someone with descent auto repair experience even if never done EV before. Any auto mechanic that has changed transmission valvebody before can handle this with proper procedure guidance. I can walk them through the process and tricky steps.

Tesla LDU

COOLANT DELETE UPDATE! After 10+ years and probably ~$1B spent by all involved, Tesla released Rev U of LDU that eliminates the rotor cooling loop by changing the coolant manifold design. Coolant no longer feeds and cool the rotor. Longevity issues from higher rotor thermals is unknown at this

sites.google.com

Hi Howard
i need to do this job on my P85. How do I contact you for assistance?

 

[howardc64]

Hi Howard
i need to do this job on my P85. How do I contact you for assistance?

EV HV is DEADLY. Understand the risks ( link )

My contacts are on LDU rebuild website here. Feel free to reach out anytime.

Tesla LDU

COOLANT DELETE UPDATE! After 10+ years and probably ~$1B spent by all involved, Tesla released Rev U of LDU that eliminates the rotor cooling loop by changing the coolant manifold design. Coolant no longer feeds and cool the rotor. Longevity issues from higher rotor thermals is unknown at this

sites.google.com

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Tesla LDU Rebuild ( link )
Model S DIY ( link )
2013 MS85 75k miles (1/25/23) Original RevB battery. 3rd (RevQ) LDU with rebuild