What might be worse than having recall work accomplished?

Perhaps having it done badly? On 5 September 2013, I took my 2006 Prius to Lake City Toyota, in Seattle, for some accumulated recall work. The accelerator pedal was trimmed, a steering issue was addressed, and the inverter pump was replaced. I also asked whether the coolant would be changed as part of this work, since there is an allowance for new coolant in the work description. They said it would. Following this service, and for the past two years, the car ran without indications of high temperatures in the inverter, or any other anomaly.

Today I changed the engine oil, and then the transmission fluid. As I prepared to add the ATF, I noticed something interesting: hose pinch pliers tightly holding the hose leading to the lower inverter cooling connection. A quick check showed there was no coolant circulation visible at the top of the tank. Removing the pliers immediately restored coolant flow. No one else had been under the hood during these two years, except myself. I had only changed the engine oil and air filter, so had not looked beneath the shroud, or at the area near the inverter and transaxle.

Did I dodge a bullet? How could the inverter survive with essentially no functioning cooling system? The temperatures aren't always moderate here in the Pacific Northwest, and even in the high 90s it never misbehaved. I'd previously considered coming up with a simple system to monitor inverter pump functioning, but I don't think that even that would have caught this. The pump was running; it simply wasn't performing its function. Effectively, my pump was dead. Yet no fault was ever indicated. And might this have had any effect on economy?

Since they obviously used the pliers to prevent coolant loss, is there any chance they changed the coolant? I think not.

Finally, do mechanics at Toyota do tool counts? Or am I thinking of the kind of care taken in aerospace shops? Some mechanic must have noticed that his hose pinch-off pliers were missing soon after this!

Lesson learned: Check everything the dealer touched. I could easily have taken the cap off of the inverter coolant tank and checked for circulation.

 

That sounds like what the dealer would say! ;-)
This was on a Gen III, right? I never found a way to do that on a Gen II.

 

1. Yes, it's always possible that no work was actually performed.
Of greater concern is the impact on the drivetrain. When I drained the ATF yesterday, after 34,000 miles, the fluid was very opaque, and dark. This surprised me, as most owners have reported little change to the fluid for this kind of mileage, and at a third change. Does age influence ATF degradation more than mileage? Or does an elevated operating temperature have an effect? Wouldn't the transmission experience an elevated temperature, if the inverter coolant path was blocked?
2. The car was only driven 9,000 miles since then.
3. I didn't log trip length or ambient temperatures. The car never took a long road trip, though. So perhaps the longest trip was something like 100 miles.
4. Yeah, I really needed that tool, too.
5. I haven't run any diagnostics, but will do that today.

Once, I found a large screwdriver rolling around near the flight control cables of my personal aircraft. But I wasn't happy to have an extra screwdriver! The mechanic just shrugged. Bad behavior isn't limited to auto mechanics!

 

Sent out a sample of the D6 ATF for a UOA. I guess this could be an extreme test of Red Line's formulation. Yeah, I know that D6 is no longer recommended as a sub for WS, but I have a lot of it around, and will keep using it until it's gone. And just maybe the Water Wetter in the inverter coolant didn't hurt.

 

In case anyone is interested, it seems that I did indeed "dodge a bullet." Despite the lack of circulation in the inverter coolant loop, and the very dark color of the D6 ATF I drained, the UOA suggests that no harm was done, at least to the transaxle. The only area of concern was the TAN of 3.6. And probably the mere 9,000 miles since the hose was pinched off limited any adverse effects. So is this a testimonial to the quality of D6 fluid, or the value of Red Line's Water Wetter? Maybe not, but I'd submit that this is not adverse evidence to their impact on the transaxle and inverter. I intend to continue using Water Wetter, and have replaced the old ATF with D6.