Howdy folks, sit down and gather round, cause I've got another fun story today from the land leaking coolant seals.
Today I pulled out this drive unit from a car that would roll, but wouldn't run. Combined with the fact that the coolant was quite low (and it clearly hadn't leaked onto the ground), I knew this was likely a situation of coolant getting into the motor, and eventually migrating all the way through to the inverter. As you can imagine, coolant and electronics don't got together very well, and the coolant (or rather mix of rust and coolant) destroyed at least one of the circuit boards, and probably a significant amount of the wiring on the inverter.
I've seen this happen on a few occasions, but it typically only happens on earlier motors (newer motors tend to seize up before coolant can ever get all the way to the inverter cavity). What's really special about this one is that once I started pulling it apart, I realized this was one of the worst looking cases of coolant caused corrosion that I have ever seen in a motor, so I thought I'd take a few pics to share here. I'm honestly quite surprised that this car was easily able to roll.
Let's start from the beginning. Here's what the speed sensor looked like when I pulled it out. Things already aren't looking good...
And here's the hole where the speed sensor goes in. I don't think I've ever seen that much debris packed in before.
Pulled the seal assembly off, and found more rust/debris. Keep in mind, almost all of this somehow made it's way through the rotor bearing, or through that little tiny hole (maybe about 1/10th of an inch in diameter) just to the right of the reluctor wheel.
Here's the failed seal itself.
At this point, I still haven't removed the rotor end cap yet. That comes after I remove the inverter, here's what I found when I removed the inverter cover, a mix of rusty coolant sludge.
The inverter itself.
Some corrosion on the connectors to the main driver board.
And some more sludge on one of the gate drive boards.
As you can see, this looks like a total disaster....and I can assure you, it is. This inverter is completely toast, beyond repair. We've tried repairing these before, but have never been able to do it successfully, so it will just need the whole thing to be replaced. Luckily, we happen to have one or two of them sitting on the shelf.
Tomorrow I'm going to start tearing into the motor itself, hopefully at least it is still rebuildable...