Tesla Large Drive Unit (LDU) Motor Teardown and maintenance

[asavage]

I am leaning towards buying the REVOLT Coolant Delete product and eliminating the problem altogether.

Unless you need a bolt-on solution and don't mind the cost, the DIY coolant manifold modification is under $50 (coming soon) and maybe a couple of hours work with tools no more complex than a hacksaw and Dremel.

I had my coolant manifold plug machined by a local hobbiest for USD$80 and the slug of alum. 6061 was under $20. The SS formed cup that should be available later this month will be half that cost. I'm not involved in that, but I have queried the person who had a prototype batch made and has a "production run" of them arriving soon. I will post purchasing info when it becomes available.

The QCC manifold is USD$770 (with tax). Revolt's is ~$550 (but eliminates the flyover tube coolant path). Both are beautiful CNC and anodized. But if you don't need pretty . . .

[asavage]

Paul is selling the SS formed caps + Loctite for $50. IDK if he has them "in stock", but they're on his sales page:

https://armstrong-mobile-forklift-repair.square.site/shop/tesla-sales/OFZJ2ZCVNNQRWQANTM2DMIU6

Do use the Loctite ("green" for sleeve or bearing mounting) and not "red" or "blue" (for thread locking). I used Loctite 640 on mine.

[muehlpower]

Has anyone thought about a simple bolt on coolant delete solution that doesn't require the tube to be sawn off and is reversible?

[asavage]

Has anyone thought about a simple bolt on coolant delete solution that doesn't require the tube to be sawn off and is reversible?

Covered in the first post of this thread. There are several on the market, QCC, Revolt, etc. Expensive.

[muehlpower]

Expensive.

Of course I know these solutions. I meant something for 20-50$ or easy to make yourself.

[asavage]

I don't know how you can have all these parameters in a single solution:

• Retain stator coolant flow
• Discontinue rotor coolant flow
• Reversible (non-destructive) modification of OEM coolant manifold
• (optional) Retain flyover tube coolant flow

A stator coolant feed adapter is simple enough to make:

But if you want to have a cover for the reluctor wheel that also accurately positions the speed sensor, that's a non-trivial fabrication, so not within your inexpensive budget. Re-using the OEM coolant manifold is much easier, but then you have to either cut off the lower section that feeds the stator (as in the pic above) or plug the rotor coolant flow with a cup/plug/epoxy and cut off the taper tube.

[muehlpower]

What do you think of two plugs, one at the end of the pipe, the other in the screwed-on line? The one in the pipe is held in place by spreading, but can of course also be pinned, in which case a hole must be drilled. It took less than an hour to make.

[asavage]

Nice idea! Not in your USD$50 budget (unless you have a lathe already, and most people do not).

If I own a CNC mill, then a bespoke coolant manifold is "simple and cheap", but for the typical person this is not the situation.

If I own a lathe, etc.

[howardc64]

@muehlpower if you have interest to further a robust seal solution, I have been making effort in US but maybe easier on EU side.

EKK has a very advanced coolant seal designed for electric motors. They have a 30mm ID x 50mm OD sample that can be supplied at volume for $120+. But it is not simple install into existing manifold (even if using a 5mm sleeve ring) Its different geometry, fits onto end of the shaft rather than slide over shaft OD like current seal. Furthermore, since all seals will leak, it is desirable to find weep chamber solution to exit any leaks. Therefore, I am guessing custom manifold is likely. I summarized this seal here ( https://teslamotorsclub.com/tmc/posts/8139931/ )

I have spoken with advanced US water pump design company to integrate this seal. Such experience is desirable as they naturally have experience to consider the key issues. For example : Lacking ICE heat to vaporized the weeped coolant ; Does the face type seal work if rotor has axial movement...

I also contacted EV Clinic and president told me they have this type of seals from ZF. He called this type seal clutch seal and said ZF is inventor and has patent. He has many samples in stock and can sell 200 EUROs each. But he isn't interested because he claims to have tested dual lip graphite seal for 250k kms ( https://evclinic.eu/product/30x55x8-tes ... -lip-seal/ ) I asked what about shaft surface condition and didn't receive any reply.

I still worry about squirrel cage rotor longevity after coolant delete (I did to my car since shaft become damaged and couldn't find any solution) But no induction motor design engineer is providing any thermal longevity analysis.

Finally, sorry I removed all my prior post. Tesla is $1T value company. LDU coolant leak problem is inviting class action lawyers from US side. Some contacted me and I don't want to be involved.

If you have interest to introduce ZF or EKK seal to water pump designers to find a solution in EU. PM me and I can connect you to EKK and EV Clinic ZF seal source.

However it is becoming more difficult to make progress developing good seal solution. Everyone is following Tesla coolant delete. If rotor failure become real, sourcing rotor will be very difficult.

[muehlpower]

Nicht in Ihrem 50-USD-Budget

I have inquired a few online fabricators in aluminum / CNC and nylon12 / 3D printing. A price under 50$ is not unrealistic even for 1 set. JLC now also makes 3D parts, not just pcb boards. https://jlc3dp.com/

[muehlpower]

At jlc3dp the price for a set in nylon is 2€! However, without spreading, but with drilling. For the O-ring set with 800 parts, from which I took the 4 O-rings, I paid 10€ at ebay. I don't think it could be cheaper.

[muehlpower]

I'm not going to remove my cooling system. Has anyone tested my sealing rings? My car is not running yet, so I have no experience. I haven't heard anything from the people I sent one to.

[asavage]

I haven't installed your seal, and I'm probably not going to, since I've gone to dry rotor. So, no feedback from me

[howardc64]

Unfortunately I didn’t install either after poor results from flame spray shaft repair.

US flame repair shop don't care about precise LDU shaft seal application. Flame sprayed over the chamfer producing sharp edges that can cut the seal lip on install. Flame spray also produces tiny porous holes. They offer to seal it but I learned sealer is chemical and requires like 200C to cure. Didn't want to bake the rotor and after failing speedi-sleeve effort. Decided to do delete.

[AlphaTango11]

Yes, you can test the stator windings at the 3-phase HV wiring at the center of the gearcase, under that orange cover with the "do not disturb" iconography. For others (sorry for the poor lighting; these are found images, not mine):

My experience on mine was that testing could be accomplished without removing those bolts and isolating the stator leads from the inverter leads; almost no change in test results occurred when I tried both methods. The access to these isn't horrible on the RAV4 EV, but IDK what access is like on the MS with the LDU in the car. As yours is on the bench, this'll be easy for you.

Yeah, it was definitely a surprisingly low reading. I had actually installed the drive unit back after only testing it with a DMM on the bench, those pictures were old. The isolation readings were later on, once I had bought the proper tester.

I read your post about testing the stator while it is still bolted (good info, tight fit on the S but still doable), and I am getting approximately 700-800kOhm on all 3 windings.

Clearly these readings are not good, so I will likely be removing the drive unit and rotor this time and attempting to dry the stator (in addition to checking the HV cables and inverter separately, since something in that chain from HVJB also had bad isolation.)

I will likely have to ultimately buy another unit or go through Tesla. I don't believe they are using coolant delete revisions on Sport LDUs, but a coolant delete (and a lighter foot on the pedal) would probably be the way to go.

Once I have the drive unit out I will retest the drive unit harness to verify its resistance as well. Thanks for your help.

I wonder what the harm is in continuing to drive it around in the meantime. It still performs just fine. At what isolation resistance would the chassis become a shock hazard, and how would a 400V ground affect the rest of the vehicle? Nevermind...

[asavage]

Revolt in Arizona says they've got https://www.myrav4ev.com/threads/anothe ... post-31095.

I can't get into the specifics, but we found a solution that dissolves the crystallized coolant without affecting the stator potting material nor the wiring insulation. Our method takes a stator with iso under 200k ohm and gets it to 40M ohm or higher (typical lately is 80 to 120 megaohm).

Not all low-iso stator can be salvaged, but if you're in a position to strip/ship/wait/pay, allowing Revolt to have a shot at it may be a viable option for you. You might find that locating "good" LDUs is getting harder, as demand for the has risen. It's not that you can't buy them, it's the price of them is going the wrong way, as the value of LDU parts (rotors, stators, inverters) seems to be rising, not falling, as more used Model S owners discover theirs have failed, and rebuilders are getting a clue, too.

Food for thought.

As there's no way for moisture to leave an LDU once it's trapped inside, running it "wet" won't dry it out; there is no air exchange. I would expect your iso to continue to decline in that environment. IOW, it's one of those cases where doing nothing (or continuing to drive it) might make it worse or render it un-dryable.

[iak78612]

Has anyone considered using oil as a coolant? It won't be as good as coolant, but probably better than a dry rotor. Thoughts?

[asavage]

Yes, it's been considered. Over on the TeslaMotors forum.

QCC's coolant delete manifold is supposedly equipped such that you could circulate eg ATF instead of a water-based coolant. AFAIK, nobody's reported actually doing that.

Meanwhile, dozens or hundreds of the SS formed cap plugs have been sold to go dry rotor. We should be hearing failure stores soon, and then we'll know the limits of not cooling the LDU rotor.

My temp monitor has never shown above 230°F in my converted RAV4 EV, but I can't push the LDU in it as hard as a real Tesla LDU, due to battery size and the Tesla software's calibration, so the Model S folks will break things first, I think.

[Boxster EV]

Having completed the delete in my circa 1250kg Porsche, so far I’ve seen a maximum motor temp spot value of 182 degrees C during spirited driving. That seems pretty hot, however it appears to be running well enough.


Edit: obviously this is the stock motor sensor, not the centre of the rotor.

[iak78612]

Yes, it's been considered. Over on the TeslaMotors forum.

QCC's coolant delete manifold is supposedly equipped such that you could circulate eg ATF instead of a water-based coolant. AFAIK, nobody's reported actually doing that.

Meanwhile, dozens or hundreds of the SS formed cap plugs have been sold to go dry rotor. We should be hearing failure stores soon, and then we'll know the limits of not cooling the LDU rotor.

My temp monitor has never shown above 230°F in my converted RAV4 EV, but I can't push the LDU in it as hard as a real Tesla LDU, due to battery size and the Tesla software's calibration, so the Model S folks will break things first, I think.

I believe the DU can get as hot as 200 C. That rules out a lot of oils because of the flash point. Will ATF be safe at higher temps? I plan on running an oil-based coolant. Seems to easy not to do.

[gpapadim]

Hello!
I have a mb250e, and here in Greece it is really impossible to find a workshop that can rebuild the tesla ldu.
Coolant delete is an option, but I would prefer to replace the coolant g48, with a dielectric fluid that doesn’t affect the motor or the inverter if it leaks. Is the new AmpCool (engineeredfluids.com) compatible? Has anyone already used it (or something similar) instead of g48 coolant?
I assume, even if the seal totally collapses and the motor is flooded with this dielectric fluid, we could drill a drainage hole somewhere and pump the fluid out of the motor once in a while.

[asavage]

I bought a gallon of "waterless coolant" that is pretty much just glycol, but I never got around to testing it in various ways -- it's still on a shelf in my garage. I had the same thought as you: minimize the damage from water. But just going "dry rotor" is a better option, IMO -- at least, that's what I did. I've put a couple thousand miles on my RAV4 EV so far with no noted ill effects.

[markmarios]

could anyone suggest a garage or DIY enthusiast preferable central Europe (BE, NL, DE, LU) that could refurbish the lard drive unit within a reasonable cost ?