Early MS LDU/RDU coolant leakage; current state of affairs

[NV Ray]

I am a 2012 P85 owner that recently proactively replaced my rear drive unit (RDU)/large drive unit (LDU) with the new - released in the Fall of 2023 -Tesla "U" version seal manifold delete/coolant delete. Proactively replacing RDU/LDU

Although I opted for a new (not reman) Tesla replacement, I learned a lot from online research and myriad discussions with 3rd party repair professionals. Here's how I understand the current state of affairs.

Early Model S's are prone to coolant leakage from within the RDU/LDU via the bearing gaskets located in the rotor. Leakage left unchecked could lead to RDU/LDU failure. Options are as follows:

1. Do nothing and don't worry about it. Either you're ok for a long time or you'll start getting alerts tommorrow.

2. Check your speed sensor for coolant.

Then either go back to option 1 or continue to the following options.

3. Replace RDU/LDU as I did.

4. Opt for a new innovation that is often called rotor coolant delete by 3rd parties or seal manifold delete by Telsa. This innovation is a device that blocks incoming coolant from reaching the rotor and "bypasses" directly to the stator, gear box, and inverter. Some 3rd party devices require RDU/LDU removal and some do not. See "Before/After" pic.

a. There are currently three types of rotor coolant delete options.

(1) Tesla's U version. $6k new, $5200 reman. See invoice and RDU/LDU pic. How Tesla's version works is unknown.

(2) 3rd Party after market devices that blocks coolant into rotor while still allowing coolant into stator, gear box and inverter. See "Before/After" pic.

(3) 3rd Party that also blocks coolant into rotor AND eliminates the "flyover pipe" reducing coolant flow into gear box. Some coolant that returns from inverter still goes to the gear box. See "Before/After" pic.

5. Another solution is to drill weep holes into bottom of RDU/LDU. Spirited discussion here. Weep Hole Weep hole +/- in previous spirited link discussion.

Note. If you already have coolant leakage then simply slapping on a coolant delete device and/or weep hole will not fix any existing coolant leakage damage issues, especially if leaking coolant has made it to the inverter. You'll need to address any current cooling leakage damage issues first.

During my research I gathered several opinions regarding the coolant delete method.

1. By bypassing rotor cooling, the rotor and associated bearings will get hotter than pre-coolant delete, simply due to no coolant being applied. However, some point out that the copper rotor has a 2000 degree F melting point and associated bearings also have a high temp tolerance. It's generally agreed that coolant delete is OK unless one is frequently drag racing or towing. Appears to be what will fail first - rotor/bearings with coolant delete option, or coolant damage with status quo.

2. Coolant delete option above that also eliminates the "flyover pipe" reducing coolant flow into gear box could lead to an air pocket forming in the gear box. Note: Tesla U version retains the "fly over pipe".

Thank you for your time.

 

[cpaull]

Thanks for the information. I also have a 2012 P85. I picked it up used from Tesla a few years ago, so I don't know if anything was ever done to the RDU.
No issues so far, hoping it stays that way.

 

[TonyWilliams]

3rd Party that also blocks coolant into rotor AND eliminates the "flyover pipe" reducing coolant flow into gear box. Some coolant that returns from inverter still goes to the gear box. See "Before/After" pic.

It’s been a VERY long time since I have been on this forum, so please excuse me in advance, if there is some policy change that I’m not aware of. I tried to post with a new profile for my company, QC CHARGE, but it doesn’t allow that.

Just to be clear, Coolant Delete from QC CHARGE for the Tesla “Large Drive Unit” from QC CHARGE does NOT eliminate the the “flyover pipe”. Quite the opposite, as it is fully integrated.

As you likely know, all of the cars with the Tesla “Large Drive Unit” (formerly the “570A” motor) have the fatal flaw of INTERNALLY leaking coolant (except for the new replacement motors with a “-U” in the part number suffix, offered starting in late 2023). Coolant Delete was never offered by Tesla in a production Model S or X (or any other car using the Large Drive Unit).

These internal leaks of ethylene glycol and water inside the motor cause a long list of issues, and represent the incipent cause of 98% of ALL failures of those motors:

* flushing the grease out of the rotor bearings, causing bearing noise and excess wear on the leaking rotor seal

* rusting and corrosion of internal components, including unprotected copper wires

* Shorting of electronics in the inverter

* Seizure of the rotor

* Loss of High Voltage isolation in the stator

We offer the “Coolant Delete” to alleviate these issues, as well as our existing “Storm Drain” for the LDU:

https: //qccharge. com/products/coolant-delete-tesla-large-drive-unit

(you can fix this link by removing the space in the link immediately after “https:” and immediately before “.com”)

So, after rebuilding almost ONE THOUSAND of these Tesla Large Drive Units (LDUs), we have developed the “fix all” for all the LDUs.

ALL OF THESE MOTORS NEED THIS MODIFICATION.

Our “Tesla LDU “Coolant Delete” retails for $599 USD, and will allow the Tesla LDU to operate with the following parameters listed below. The physical rotor does not need cooling. It is a 60 pound spinning mass of steel and copper.

But, what might need cooling are the two bearings on the rotor shaft. That’s what the original Tesla design (the design that leaks and causes internal damage to the motor) was supposed to do.

If high quality ceramic rotor bearings are used, like QC CHARGE uses in all Tesla motor rebuilds, they don’t really need much cooling. Coolant delete of the Rotor Center Shaft does not affect the motor’s stator (field), inverter, nor the gearbox cooling with ethylene glycol.

This is different than the competitors, that do not offer the original glycol cooling of the gearbox oil. Aluminum corrodes, so we took steps to mitigate that corrosion, including anodizing our “Coolant Delete” in a pretty red color. Be careful with “raw aluminum” copies.

In addition, we ONLY inhibit water cooling of the center rotor shaft, and no other motor area. If coolant is also deleted from the gearbox oil (the aluminum tube in the top), of course, it won’t cool that oil, and it may be very difficult to bleed all the air out of the system.

Our units have been “race tested”, with many home built and professionally built Tesla “Large Drive Units” using our “Coolant Delete” now, without issue.

For 99.9% of all the Tesla Large Drive Units in use, cooling of the rotor shaft is not needed. But, ALL of our “Coolant Delete” units have the ability to add oil cooling. For the folks who do use it, they certainly think it’s important. Nobody else offers this, not even Tesla.

All those additional features, engineering, and performance that we use costs extra, but we think it’s worth the small extra cost. Why would anybody want to save $100 on a super critical part for any motor that costs many thousands of dollars?

1) Coolant Delete of the rotor center shaft only. This is what we offer, at QC Charge, and what Tesla is offering with their “-U” replacement motors. This is the lowest level of “fix”, as it does fix the horrific failure modes from a leaking rotor seal. It is imperative that every Tesla “Large Drive Unit” have this modification. EVERY SINGLE ONE.

2) OPTIONAL - Oil Cooling of the rotor ONLY. Yes, while the rest of the components are cooled with the same G48 or other ethylene glycol and water based coolants, the rotor can be specifically cooled with Dexron VI or 212B gearbox oil, which will provide the following benefits. To be clear, over 99.9% of all LDUs will NOT need oil cooling, but here’s what is optionally available:

a. Actual cooling of the rotor, which doesn’t need cooling at all, but in EXTREME duty, the bearings that hold the rotor may need this oil cooling.

b. When the rotor seal leaks (and it will, eventually), Dexron VI is benign to the LDU. It won’t destroy the stator, it won’t seize and rust the rotor, and it won’t short out the inverter.

c. No fatal failures of the motor!!! If all the Dexron VI leaked out, you would just have a “coolant delete” motor!

Using the Dexron VI cooling method will require additional parts, at extra cost (oil pump from Tesla Model 3/Y, coolant tank, radiator, and hoses and fittings). We do not currently have plans to support the additional parts required.


************

Don’t let a leaking seal in your Tesla motor cause expensive damage!

For the following vehicles:

NOTE: you can fix the following links by removing the two spaces in the link, one immediately before “.be” in YouTube and the other space immediately after “http:”)

A - 2012-2014 Tesla Model S (all)
https: //youtu. be/qL1Dhv0WD30

B - 2015-2020 Tesla Model S and X, Performance versions (all - rear drive motor only) as well as Rear Wheel Drive (RWD - all). The only vehicles NOT affected are non-Performance “D” cars with dual Small Drive Units, for example 70D, 75D, 85D, 90D, and 100D, none of which are affected.
https: //youtu. be/qL1Dhv0WD30

C - 2014-2017 MERCEDES B-Class ED / B-Klasse ED / B250e (all)
https: //youtu. be/txD7u2DKanE

D - 2012-2014 Toyota RAV4 EV (all)
https: //youtu. be/XfncTZcsSHM

 

[OVB1]

Thanks for the information. I also have a 2012 P85. I picked it up used from Tesla a few years ago, so I don't know if anything was ever done to the RDU.
No issues so far, hoping it stays that way.

Does anyone know if the U version will be same for 2016.5 S75? Taking my car into Tesla a few months before warranty expires to see if there’s a leak and hopefully they’ll replace LDU with U version if yes.

 

[NV Ray]

Does anyone know if the U version will be same for 2016.5 S75? Taking my car into Tesla a few months before warranty expires to see if there’s a leak and hopefully they’ll replace LDU with U version if yes.

Surest answer is with Tesla. Remember to stress "seal manifold delete" vs U version in case your year drive unit has not gone that far in the alphabet of revisions.

 

[scgaskill]

I am a 2012 P85 owner that recently proactively replaced my rear drive unit (RDU)/large drive unit (LDU) with the new - released in the Fall of 2023 -Tesla "U" version seal manifold delete/coolant delete. Proactively replacing RDU/LDU

Although I opted for a new (not reman) Tesla replacement, I learned a lot from online research and myriad discussions with 3rd party repair professionals. Here's how I understand the current state of affairs.

Early Model S's are prone to coolant leakage from within the RDU/LDU via the bearing gaskets located in the rotor. Leakage left unchecked could lead to RDU/LDU failure. Options are as follows:

1. Do nothing and don't worry about it. Either you're ok for a long time or you'll start getting alerts tommorrow.

2. Check your speed sensor for coolant.

Then either go back to option 1 or continue to the following options.

3. Replace RDU/LDU as I did.

4. Opt for a new innovation that is often called rotor coolant delete by 3rd parties or seal manifold delete by Telsa. This innovation is a device that blocks incoming coolant from reaching the rotor and "bypasses" directly to the stator, gear box, and inverter. Some 3rd party devices require RDU/LDU removal and some do not. See "Before/After" pic.

a. There are currently three types of rotor coolant delete options.

(1) Tesla's U version. $6k new, $5200 reman. See invoice and RDU/LDU pic. How Tesla's version works is unknown.

(2) 3rd Party after market devices that blocks coolant into rotor while still allowing coolant into stator, gear box and inverter. See "Before/After" pic.

(3) 3rd Party that also blocks coolant into rotor AND eliminates the "flyover pipe" reducing coolant flow into gear box. Some coolant that returns from inverter still goes to the gear box. See "Before/After" pic.

5. Another solution is to drill weep holes into bottom of RDU/LDU. Spirited discussion here. Weep Hole Weep hole +/- in previous spirited link discussion.

Note. If you already have coolant leakage then simply slapping on a coolant delete device and/or weep hole will not fix any existing coolant leakage damage issues, especially if leaking coolant has made it to the inverter. You'll need to address any current cooling leakage damage issues first.

During my research I gathered several opinions regarding the coolant delete method.

1. By bypassing rotor cooling, the rotor and associated bearings will get hotter than pre-coolant delete, simply due to no coolant being applied. However, some point out that the copper rotor has a 2000 degree F melting point and associated bearings also have a high temp tolerance. It's generally agreed that coolant delete is OK unless one is frequently drag racing or towing. Appears to be what will fail first - rotor/bearings with coolant delete option, or coolant damage with status quo.

2. Coolant delete option above that also eliminates the "flyover pipe" reducing coolant flow into gear box could lead to an air pocket forming in the gear box. Note: Tesla U version retains the "fly over pipe".

Thank you for your time.

Thanks for sharing all this! Earlier this week I had my ICE mechanic whom I trust more than the SC, do the annual break caliper maintenance and also check the speed sensor. Neither of those is "rocket science" requiring Tesla SC expertise.

He charged me $131 total and found my speed sensor to be dry as a bone! Whew!

Now I'm trying to decide how to keep it that way w/o spending thousands proactively replacing the LDU as you did. I'm curious about the "weep holes". I've been off FB for several years but may have to rejoin to read that spirited discussion.

 

[NV Ray]

Thanks for sharing all this! Earlier this week I had my ICE mechanic whom I trust more than the SC, do the annual break caliper maintenance and also check the speed sensor. Neither of those is "rocket science" requiring Tesla SC expertise.

He charged me $131 total and found my speed sensor to be dry as a bone! Whew!

Now I'm trying to decide how to keep it that way w/o spending thousands proactively replacing the LDU as you did. I'm curious about the "weep holes". I've been off FB for several years but may have to rejoin to read that spirited discussion.

If your speed sensor was dry, great news. After warranty is up you could do one of the 3rd party coolant bypasses and/or weep hole.

Just to double check, you have single large rear drive unit or dual motor? If latter, I'd recommend no action as dual drive units seem to have a more reliable history in regards to coolant leakage. I don't know why.

 

[scgaskill]

If your speed sensor was dry, great news. After warranty is up you could do one of the 3rd party coolant bypasses and/or weep hole.

Just to double check, you have single large rear drive unit or dual motor? If latter, I'd recommend no action as dual drive units seem to have a more reliable history in regards to coolant leakage. I don't know why.

It's a single LDU, RWD and it's already out of warranty with Tesla but I do have a CarShield warranty that will cover it. Yesterday I repaired my leaking left inner tail light. And put on the new custom plates...