Help with codes and driveline issue - incorrect diagnosis by Service

[rjcampeau]

My 2013 S60 RWD recently presented with stuck rear brake caliper symptoms, that e-brake feeling when driving at speed and sticking/almost jerking when accelerating at slow speeds. So much that I stopped driving it, and had it towed to service. Upon inspection, the service center found a parking brake caliper code and replaced those calipers at a cost of $1800. Unfortunately, this replacement did not solve the problem, and now they want to try new axles for $2300, and if that fails, they suggest it may be an issue with the drive unit.

However, I suspect that the service center may have overlooked some basic diagnostic procedures (like driving the car to see if a rotor heats up more than the others) and may have cost me unnecessary expenses. Around 11 months ago, I had to replace my parking brake pads after one of the pads fell off the metal backing. During that time, I drove the car for a bit without a parking brake caliper on one side, which threw a few parking brake codes along the way. I am concerned that the service center may have identified those old codes and charged me $1800 for replacing the calipers for no reason. Is there any way to verify this?

Furthermore, I am unsure if the service center is properly diagnosing the root cause of the issue, and I am not willing to spend $4k to find out I may need to replace the drive unit without proper confirmation that this is the problem. I would appreciate any advice on how to diagnose this issue beyond what the service center is trying @wk057 . It seems like they are focused on just throwing parts at the problem instead of proper diagnosis and repair techniques, which is great for cars under warranty, but not for me.

Thanks!

 

[TLLMRRJ]

That's terrible.

You could buy your own $18 infrared thermometer to see if one or both of the brake disks are overheating after driving some distance.

Amazon.com

 

[NewbyMaybe]

How old is your drive unit? They are known for causing problems.

 

[rjcampeau]

That's terrible.

You could buy your own $18 infrared thermometer to see if one or both of the brake disks are overheating after driving some distance.

Amazon.com

Unfortunately its stuck at a Tesla Service centre now, too late for me to do their job for them at this point unless I tow it back home (I live too far to take the chance of driving it)

 

[rjcampeau]

How old is your drive unit? They are known for causing problems.

This one was installed in 2019. Is this a symptom of DU failure, even without error codes?

 

[TLLMRRJ]

Unfortunately its stuck at a Tesla Service centre now, too late for me to do their job for them at this point unless I tow it back home (I live too far to take the chance of driving it)

Understand.

Can you drive to the Service Center, then test drive it yourself just around the Service Center to check the temps and then put it back in the Service Center? That way no tow, or risky long drives.

I know it seems inconvenient and ridiculous, but your alternative to letting Tesla just do their thing is potentially a ~$10K bill for you.

 

[rjcampeau]

My 2013 S60 RWD recently presented with stuck rear brake caliper symptoms, that e-brake feeling when driving at speed and sticking/almost jerking when accelerating at slow speeds. So much that I stopped driving it, and had it towed to service. Upon inspection, the service center found a parking brake caliper code and replaced those calipers at a cost of $1800. Unfortunately, this replacement did not solve the problem, and now they want to try new axles for $2300, and if that fails, they suggest it may be an issue with the drive unit.

However, I suspect that the service center may have overlooked some basic diagnostic procedures (like driving the car to see if a rotor heats up more than the others) and may have cost me unnecessary expenses. Around 11 months ago, I had to replace my parking brake pads after one of the pads fell off the metal backing. During that time, I drove the car for a bit without a parking brake caliper on one side, which threw a few parking brake codes along the way. I am concerned that the service center may have identified those old codes and charged me $1800 for replacing the calipers for no reason. Is there any way to verify this?

Furthermore, I am unsure if the service center is properly diagnosing the root cause of the issue, and I am not willing to spend $4k to find out I may need to replace the drive unit without proper confirmation that this is the problem. I would appreciate any advice on how to diagnose this issue beyond what the service center is trying @wk057 . It seems like they are focused on just throwing parts at the problem instead of proper diagnosis and repair techniques, which is great for cars under warranty, but not for me.

Thanks!

@ajbessinger looking at other threads it seems like you would be the closest shop to my location that does independent driveline repairs - does this sound like driveshaft or drive unit failure to you? Thanks!

 

[KalJoMoS]

Before you go to the DU route can you ask the service to look for the ABS sensor failure, here is one possible solution that might just be it, as you have clearly “solved” that parking brake issue.

 

[ajbessinger]

@ajbessinger looking at other threads it seems like you would be the closest shop to my location that does independent driveline repairs - does this sound like driveshaft or drive unit failure to you? Thanks!

I highly doubt that the issue has anything to do with the axles. What seems more likely to me is a seizing drive unit. This is not uncommon on drive units that have had a SLOW rotor coolant seal leak, which ends up creating a bunch of corrosion in the stator housing. The buildup of corrosion essentially "squeezes" the rotor in place, making it difficult (or in some cases even near impossible) to turn.

Has the service center even bothered to check the speed sensor on the drive unit to see if an internal coolant leak is present? Unfortunately most Tesla techs are just trained to remove and replace parts with no real thought put into proper diagnostics... I would bet that 95% of Tesla techs have never even seen the inside of an LDU, let alone know how/why they fail.

In the case of a 3rd party repair, we can press the rotor out of the case, but generally speaking when we encounter a motor with this level of corrosion in the stator, we would recommend a replacement stator assembly (which basically means transferring all the internals over to a different motor case). If the old stator is reused, it will likely work for awhile, but the coolant that has already soaked into the resin can lead to further corrosion and loss of HV isolation in the future. In this type of scenario, a reman drive unit from Tesla would likely be cheaper than a rebuild with a replacement stator...

I actually just finished up an LDU rebuild on a Mercedes B-Class that had a seizing rotor, and we did replace the stator assy. It's a little bit of a different story on those though, as Mercedes charges ~$12-15k for a replacement drive unit, so it makes a bit more sense to go to those lengths to do a rebuild on one of those (same goes for the RAV4 EV).

 

[ajbessinger]

I highly doubt that the issue has anything to do with the axles. What seems more likely to me is a seizing drive unit. This is not uncommon on drive units that have had a SLOW rotor coolant seal leak, which ends up creating a bunch of corrosion in the stator housing. The buildup of corrosion essentially "squeezes" the rotor in place, making it difficult (or in some cases even near impossible) to turn.

Has the service center even bothered to check the speed sensor on the drive unit to see if an internal coolant leak is present? Unfortunately most Tesla techs are just trained to remove and replace parts with no real thought put into proper diagnostics... I would bet that 95% of Tesla techs have never even seen the inside of an LDU, let alone know how/why they fail.

In the case of a 3rd party repair, we can press the rotor out of the case, but generally speaking when we encounter a motor with this level of corrosion in the stator, we would recommend a replacement stator assembly (which basically means transferring all the internals over to a different motor case). If the old stator is reused, it will likely work for awhile, but the coolant that has already soaked into the resin can lead to further corrosion and loss of HV isolation in the future. In this type of scenario, a reman drive unit from Tesla would likely be cheaper than a rebuild with a replacement stator...

I actually just finished up an LDU rebuild on a Mercedes B-Class that had a seizing rotor, and we did replace the stator assy. It's a little bit of a different story on those though, as Mercedes charges ~$12-15k for a replacement drive unit, so it makes a bit more sense to go to those lengths to do a rebuild on one of those (same goes for the RAV4 EV).

Here's what the rotor and stator end up looking like on a seizing up motor:

 

[TLLMRRJ]

Has anyone considered switching to waterless coolant to reduce the damage from coolant leaks in the drive unit or batteries?

Waterless coolant is great because it doesn't have water to create corrosion and is much less conductive. I use it in ICE cars that have plastic pipes in the cooling system because without water, there's no pressure in the cooling system even though the engine is at full temp. That pressure eventually splits the plastic pipes as they weaken with age, and also blows out the water pump seals.

It's a lifetime coolant as well, and it has had no negative effects on any of the car's cooling capacity on my cars.

With waterless coolant, by the time you notice the loss of coolant, it's probably not the end of your MS drive unit, like it is with conventional coolant.

Seems like a really good use case for early MS's.

Preventing Electrolysis | Evans Waterless Coolant

Evans Waterless Coolant prevents electrolysis, which preserves your engine.

www.evanscoolant.com

 

[ajbessinger]

Has anyone considered switching to waterless coolant to reduce the damage from coolant leaks in the drive unit or batteries?

Waterless coolant is great because it doesn't have water to create corrosion and is much less conductive. I use it in ICE cars that have plastic pipes in the cooling system because without water, there's no pressure in the cooling system even though the engine is at full temp. That pressure eventually splits the plastic pipes as they weaken with age, and also blows out the water pump seals.

It's a lifetime coolant as well, and it has had no negative effects on any of the car's cooling capacity on my cars.

With waterless coolant, by the time you notice the loss of coolant, it's probably not the end of your MS drive unit, like it is with conventional coolant.

Seems like a really good use case for early MS's.

Preventing Electrolysis | Evans Waterless Coolant

Evans Waterless Coolant prevents electrolysis, which preserves your engine.

www.evanscoolant.com

We are actually working on a kit which would convert the rotor from "water based" cooling to oil cooling. It would effectively separate the rotor cooling to it's own separate circuit, and hopefully have a couple benefits:
1) Keep the rotor seal in good working order for a longer period of time (better lubricating properties for the seal).
2) IF the seal leaks, the oil is non-conductive, and should have no adverse effects on the motor internals.

 

[TLLMRRJ]

We are actually working on a kit which would convert the rotor from "water based" cooling to oil cooling. It would effectively separate the rotor cooling to it's own separate circuit, and hopefully have a couple benefits:
1) Keep the rotor seal in good working order for a longer period of time (better lubricating properties for the seal).
2) IF the seal leaks, the oil is non-conductive, and should have no adverse effects on the motor internals.

That sounds like a lot of work and expense compared to just changing to a waterless coolant.

How much do you think that conversion will cost to purchase and install?

 

[rjcampeau]

I highly doubt that the issue has anything to do with the axles. What seems more likely to me is a seizing drive unit. This is not uncommon on drive units that have had a SLOW rotor coolant seal leak, which ends up creating a bunch of corrosion in the stator housing. The buildup of corrosion essentially "squeezes" the rotor in place, making it difficult (or in some cases even near impossible) to turn.

Has the service center even bothered to check the speed sensor on the drive unit to see if an internal coolant leak is present? Unfortunately most Tesla techs are just trained to remove and replace parts with no real thought put into proper diagnostics... I would bet that 95% of Tesla techs have never even seen the inside of an LDU, let alone know how/why they fail.

In the case of a 3rd party repair, we can press the rotor out of the case, but generally speaking when we encounter a motor with this level of corrosion in the stator, we would recommend a replacement stator assembly (which basically means transferring all the internals over to a different motor case). If the old stator is reused, it will likely work for awhile, but the coolant that has already soaked into the resin can lead to further corrosion and loss of HV isolation in the future. In this type of scenario, a reman drive unit from Tesla would likely be cheaper than a rebuild with a replacement stator...

I actually just finished up an LDU rebuild on a Mercedes B-Class that had a seizing rotor, and we did replace the stator assy. It's a little bit of a different story on those though, as Mercedes charges ~$12-15k for a replacement drive unit, so it makes a bit more sense to go to those lengths to do a rebuild on one of those (same goes for the RAV4 EV).

Ahhhh ok, this makes so much more sense. I recently bought a new car and stopped driving it on a regular basis, which sounds like perfect conditions for this problem to manifest. But also a perfect way for a brake caliper to seize, which was why this was so confusing.

This morning Tesla put it up on the hoist in dyno mode and ruled out the drive shafts, and diagnosed it as an internal drive unit issue, which means full replacement for just under $10k CAD ($7500 USD). There is zero chance they pulled the speed sensor to check for coolant, however they did check the fluid for metal shavings at my suggestion (there were none). Sounds like full replacement is the way to go based on what you're saying, also there isn't an inexpensive/easy way to get my car or drive unit to the States and back to take advantage of your services.

I still need to get my car from Victoria to Vancouver since my local centre is not equipped to do drive units - is there much risk in just driving it like this? Once I get going, it smooths out. The trip is about 45 miles, and involves a ferry ride where I would strongly prefer not to get stuck on the boat! Otherwise a tow will cost me $1100.

Thanks!!