Inverter only or whole system coolant liquid (i.e. are they same or separate)?

It has two separate cooling systems. One for engine and one for inverter bought use same (pink) Toyota Super Long Life Coolant. Flushing isn’t good for Prius since especially engine coolant can’t be drained completely and SLLC is premix.

 

Two different coolant systems, one for the Inverter/Converter module plus transaxle and one for the ICE. That is why you have two Coolant Reservoirs in your engine compartment with pink coolant. Same coolant specs for both systems.

A flush is not needed for the Prius, only a drain and refill. The systems will need to be free of air entrapment after the coolant refill but since it is your dealer they should know this.

 

Inverter coolant is easy but you should get new sealing washer for its drain. Engine coolant is lot trickier 100K maint - 5

 

Patrick Wong has written detailed post's on the subject. A Google search will reveal these posts.

FWIW, both systems must be bled to operate correctly. There is a bleeder on top of the radiator to bleed the ICE part of the system.

As written above, only use the Toyota SLLC (Super Long Life Coolant). Also be aware that filling the overflow bottle for the radiator is NOT sufficient when filling or refilling the coolant loop. The radiator cap must be removed and the radiator must be filled at the same time as filling the overflow bottle.

If you ever get air trapped in either system, said system will overheat and cause the red triangle of death.

No flushes are ever needed nor are they recommended. Drain, refill, and bleed all air.

Again, do a Google search for the process. It is well documented here on Prius Chat

Ron (dorunron)

 

Here is a picture of what the Gen II Prius radiator will look like when it is full. In order to access the cap, you must remove the splash guard over the radiator first. Don't forget, only use Toyota SLLC.

 

If you were viewing your Gen II as looking at the pic above, the bleeder screw would be found on top of the radiator about two feet away towards the drivers side on top. Look for the warning label. It looks like a little hex head screw that can be seen through the metal over the radiator. Can't describe it any better than that. Open the bleeder when filling the radiator. This helps to remove air pockets.

 

If its less than 100K miles don't bother dumping the entire engine coolant system. Its a real pain to bleed the engine. And if you really mess it up you can easily overheat the motor and with an aluminum head that's bad. With no thermometer on the dash you don't even know the motors overheating till too late the dash board lights up. Way to late to help. This little motor is very easy on the engine coolant. All I do is once a year dump the rad only and fill it back up with SLLC. Now years later the fluid looks like new.

Now conversely the Inverter is very hard on its coolant but is very very easy to change out. I do the trans fluid every 30K and since I'm under the car I just open the I Coolant dump bolt and dump the I coolant. Every 30K. Fill it up...start the car and bleed it while filling it.

Go after the trans and I coolant much much better bang for your buck. You will rewarded with much better mileage and longer life of the Inverter which is the heart and soul of this car and the very expensive trans.

 

would 1 /gal of coolant get the inverter changed out/? inverter and radiater fluid look like new

 

Yes one gallon of Toyota Sllc should do the inverter.
With the dump bolt out pour some distilled water
In the reservoir to flush it out.