Tesla Small Drive Unit (SDU) Gear Box Fluid leaked

[alexbeatle]

Folks,
Sometime ago I resealed my SDU due to gearbox oil leak. I then refilled it with fresh oil.

I did not have the setup to spin the drive unit at the time.
Today, I was ready to spin it. Wanted to do a basic motor test before applying HV. Pulled the below orange rubber plug (phases connections cover) and lot's of fresh gearbox oil poured out. I quickly plugged it back, but quite a bit came out.
Does it mean I damaged something in my drive unit when I was resealing?? I did not expect the gearbox oil to be where the motor connections are.
Please let me know.

The + and - on the input tested fine:
+ to - precharged and then showed open circuit
- to + settled on 0.555 ohms

[alexbeatle]

Ok. I'm prepping myself to pull the unit out and so refreshing my memory how I took things apart last time.
In doing so, looks like the gearbox and the motor (rotor and stator) section are suppose to have gear fluid. Before I was thinking that only the gearbox section should be in the fluid.


Inverter section should not be having any gear fluid., which is why these wires from the inverter to the motor windings have o-rings and a cover.

I'll start by removing the inverter side and see if any obvious damages can be spotted.

If any of the o-rings or grommets are damaged, can I simply seal these wires with a gasket maker? Like this one...

I'm prepared for the worse, but lets see if any gods old or new are on my side....I was communicating with the drive unit and changing parameters, just didn't apply any bus voltage yet.

[alexbeatle]

Ok. I couldn't wait until the weekend to do everything at once. Doing bit by bit when I get a minute..
Drain fluids...oil and coolant ..

Some was found in the HV ports too

I think this is where it started the leak..

A little pre-story. I received the DU bone dry. I swapped the board and bench tested. Put in the vehicle. Filled up and moved on to doing other tasks of conversion. After a while started noticing some drips from the gearbox as shown previously. Drained, pulled out the DU, opened it up, resealed, refilled. No leaks from the gearbox on the outside after that. Maybe it's been damaged during me disassembling, but chould be that it's been leaky from day 1...

At this point I should assume all electronics parts have been touched by the gearbox fluid.

Please let me know if you have any suggestions on cleaning and testing?

[alexbeatle]

Planning to clean the LV drop in board with just a contact cleaner.
Not sure what to do with the HV IGBT section. Doesn't seem like it's dismantable.
https://youtu.be/1Hdr3wlHCAY?si=GncX2P1 ... Hf&t=3m38s

[jrbe]

O-ring + make a gasket = almost a guaranteed leak. Best to make sure all the o-ring grooves and bores are clean and not scratched. Use new o-rings.

Isopropyl alcohol should work well to clean all of this. Make sure it's completely dry before you assemble it.

[alexbeatle]

O-ring + make a gasket = almost a guaranteed leak. Best to make sure all the o-ring grooves and bores are clean and not scratched. Use new o-rings.

Isopropyl alcohol should work well to clean all of this. Make sure it's completely dry before you assemble it.

Thank you.

Cannot clean inside of the IGBT section, can I? Doesn't look disasembable.

[jrbe]

At the worst you should be able to pour isopropyl alcohol into the power stage section and swirl it around. Doing this a few times should get it clean. Making sure it's dry might be challenging though.

[alexbeatle]

At the worst you should be able to pour isopropyl alcohol into the power stage section and swirl it around. Doing this a few times should get it clean. Making sure it's dry might be challenging though.

Yeah. If it was LV I'd do it without thinking.

[alexbeatle]

Opened the motor leads cover. All o-rings look clean and undamaged. The cover looks clean too.

Planning to make a gasket on the cover using the gasket maker I used to fix the other leak - permatex optimum black (sensor safe). Though that was metal-to-metal, this will be plastic-to-metal. Should work just as good, right?

These folks use some kind of rubber lube, anybody familiar with this product?

[modellfan]

Interestingly I had the same issue and already started a topic on this: viewtopic.php?t=4143. Therefore I am very interested in your outcome. My SDU Rear unit is leaking just around one drop per day into the inverter housing. When I bought it used it hat just some dozens of ml in the inverter. I am pretty sure that this is the temperature sensor leaking. It is loose (see the video in my post) and I rarely can't feel a press fit of a o-ring.

However it is looking different then yours not having a rubber gromet on it, I am looking forward to see your solution to remove the leak. If you have some pictures frome the other side of the temperature sensor I am realy interested about it.

[jrbe]

These folks use some kind of rubber lube, anybody familiar with this product?

Your best bet is to use a dab of transmission oil as the lube. Mixing different lubes / oils / greases can have bad results.

For the loose temp sensor o-ring, you could likely find a thicker o-ring that fits properly that's compatible with Tesla transmission oil. Sounds like they aimed too low on the o-ring squish % or ended up with a temp sensor with a smaller o-ring OD area.

[alexbeatle]

Used the optimum gasket maker.
Put a thin layer on the inside of the holes of the plastic cover to seal any gaps between plastic and wires. Made a thin gasket between the plastic cover and the metal of the of the frame. Thin layer inside of the sensor hole. Hand tightened.
Torqued after 1h of curing.
Put a generous layer of gasket maker around the edges.
Waited 24h.
Filled with new ATF.
Spun both wheels at the same time every once in a while so that the oil pump would push the fluid all around.
24h later, so far no leaks - see attached
Sure it looks ugly, but if it works it works...
This gasket maker is super flexible, should allow for any movements without compromising the seal.