Inverter Coolant Oily

Posting a picture would be good. not sure what the oil film looks like. The dried up white stuff could be old coolant that dried up from sitting in one place for too long and it drys up from the engine heat. I mean these are my guesses, won't know for sure until we see it and figure what's the issue.

 

just replace it

 

I can't think of a way oil from the engine could get into the inverter coolant circuit. It could be a tiny bit from assembly lube used when the car was made. A small amount (a skim or sheen on top) won't harm anything. Replace the fluid when called for by Toyota (they have extended the interval, doubling it now from what it was).

 

Yeah but transaxle fluid?

 

No, not even transaxle fluid. The inverter is separate from all mechanical parts, only joined by wires.

 

The inverter coolant drain bolt is on the underside of the transaxle though, maybe coolant channel run through the transaxle as well?

With thanks to @NutzAboutBolts :



And from the Repair Manual:

 

we won't know until we see the pictures

 

According to what I've read, the inverter coolant does take a trip through the MG's, cooling the stator windings. Don't know about the oily. Could have been from assembly, if the SLLC is original. Or maybe somewhere down there the SLLC is encountering ATF-WS.

 

Well, wherever it runs, I wouldn't worry about it unless it turns "milky". A tiny bit of oil (film on top) won't harm anything.

 

Yeah that could well be some assembly grease, as you said.

 

Unless the OP is the only one to have ever touched the engine bay since new, someone over the past 7 years could have begun to mistakenly add another fluid (brake or oil) to the inverter coolant tank and stopped after putting a few CC's in when the mistake was realized. It's a possibility.

 

Looking at the drain photo. The fluid got all over the bottom of the transaxle case. Any oil on the bottom of the case may have been washed of by the draining fluid, and this could make the small oily sheen at the top of the drained fluid.

Photo from @NutzAboutBolts :

View attachment 133490

 

Maybe the drain pan was also used for oil changes, some residue?

 

Or the same funnel used for oil changes was used without cleaning to change out or top off the coolant tank.

 

Yeah even if oily plastic is wiped with a clean cloth it'll retain a bit of oil. I try to segregate funnels: one for coolant or washer fluid, one for engine oils, a long tapered one for Honda auto transmission, a special one with hose for Prius transaxle, another similar one for Honda rear differential. I've got a funnel corral lol.

 

I have a funnel.

 

The medium sized white one, middle-back, is for adding motor oil. Biggie, at left-end-back is the drain oil catch funnel. White one directly in front of it is for coolant and washer fluid. Tiny one front-left with long hose extension is for Honda rear differential. Black one front center has a 3' hose extension (obscured), for Prius transaxle. Kirkland mayo jar (hole in lid) with syringe, tube and adapter is for brake fluid change. And indispensable graduate. There are more funnels/tubes, just haven't needed them yet, lol.

 

Where is the OP? Scared away with all our speculating?

 

He might not return given how many funnels @Mendel Leisk has.

I have 2 funnels: one with a large opening and one with a small opening.

Contamination at minute levels should not pose any long term damage to the systems.

But creates great conversation .