Toyota Highlander Hybrid coolant question

[paulri]

Does the engine coolant get mixed in with the inverter coolant? In other words, if I do a simple radiator drain & fill, will that also affect the coolant that reaches the inverter, or is that a separate system? this is for the 2006 in my sig

 

[nthach]

Nope - separate heat exchanger for the hybrid cooling loop. Only the 1st-2nd gen Prius combines the engine radiator and the hybrid coolant heat exchanger into one integrated unit with separate circuits. It might look like it's together but there's a split in the core.

 

[paulri]

Ok, I just peeked underneath and it looks like the petcock is connected to the inverter radiator, which I thought meant that it was one integrated system. OK well the transaxle plug that I need to access is actually very easy to get--w/o ramps, so I should be ok.

Now how important is it to open up the air vent towards the top of the radiator? I was seeing on youtube that you have to take off the grill for that. If I am willing to take the time to burp the system with the radiator, and make sure that the inverter reservoir stays full, isn't that enough?



Originally Posted by nthach
Nope - separate heat exchanger for the hybrid cooling loop. Only the 1st-2nd gen Prius combines the engine radiator and the hybrid coolant heat exchanger into one integrated unit with separate circuits. It might look like it's together but there's a split in the core.

 

[The_Jeff]

I would do what it takes to burp coolant by-the-book. Even then it can be daunting.

I would get an OBD dongle and watch the data stream for modest overheating or temp swings while you drive around after doing this. Dash gauges, if you have them, are very dead in the middle of the range.

 

[paulri]

I'll go ahead and remove the grill (which is what is required to do it by the book). I decided to do a "practice run" this morning, and remove the grill and get the crush washer for the transaxle plug, and then next weekend or two, I'll do the actual drain & fill then.

Now when you say "very dead in the middle of the range," do you mean that they are not very sensitive to temp swings? And that there could be more of a swing in temps than my car is telling me?


Originally Posted by eljefino
I would do what it takes to burp coolant by-the-book. Even then it can be daunting.

I would get an OBD dongle and watch the data stream for modest overheating or temp swings while you drive around after doing this. Dash gauges, if you have them, are very dead in the middle of the range.

 

[PandaBear]

Is there a need to exchange the inverter coolant (other than radiator replacement)? There's no combustion gas to contaminate it and should last longer than the electronics or the car.

My understanding is the dual coolant system is for different temperatures between engine and inverter.

 

[paulri]

That's a very good question. The manual said to check or change the engine and inverter coolant (can't find it right now for the exact interval), so I only assumed that if I had to check it, it might need replacing. The last time it might have been replaced was 5 years ago, so I felt it was time. The coolant itself is TSLLC, which is (at this point in the car's life) a 5 year coolant.


Originally Posted by PandaBear
Is there a need to exchange the inverter coolant (other than radiator replacement)? There's no combustion gas to contaminate it and should last longer than the electronics or the car.

My understanding is the dual coolant system is for different temperatures between engine and inverter.

 

[The_Jeff]

Originally Posted by paulri

Now when you say "very dead in the middle of the range," do you mean that they are not very sensitive to temp swings? And that there could be more of a swing in temps than my car is telling me?



Yes, absolutely. My prius has no gauge at all and varies from 140-190'F just driving around at approx freezing temps.

If you have a gauge I'm confident it's been "deadened" by the computer so people don't freak out. At the loss of an ability to be one with your car and noticing subtle changes in performance.

 

[nthach]

Originally Posted by paulri


Now how important is it to open up the air vent towards the top of the radiator? I was seeing on youtube that you have to take off the grill for that. If I am willing to take the time to burp the system with the radiator, and make sure that the inverter reservoir stays full, isn't that enough?


Most indie shops will use a Airlift to vacuum bleed the inverter loop(you drain it from the transaxle) - but last time I did a D&F of my inverter coolant, I put the car in deadhead and I had the inverter pump bleed the system.

 

[paulri]

At this point, after double checking my service maintenance manual, it did explicitly state to change the inverter coolant, so I'll do that when I drain & fill the engine coolant. How necessary it is, is another question. I'll play it on the safe side and change it.

Originally Posted by PandaBear
Is there a need to exchange the inverter coolant (other than radiator replacement)? There's no combustion gas to contaminate it and should last longer than the electronics or the car.

My understanding is the dual coolant system is for different temperatures between engine and inverter.