Coolant Flush 01'

Your confused. The "electric side does not have an overflow tank". Thats the engine side.
The Inverter what you call electric side does have its own reservoir next to the inverter.

The gas side has an overflow tank above the radiator and is not cake to bleed in fact its a major hassle to bleed as air gets trapped in the CHRS thermos bottle and to be done correctly the bottle pump must be tricked on via its power relay to circulate. Many posts about it. Search.

Hopefully Patrick will stumble onto this post and help you.

 

The Classic forum is a subforum within the Gen II Main Forum, here:
Generation 1 Prius Discussion | PriusChat

In any event, it is pretty difficult to purge air out of the Classic inverter coolant loop. The Toyota repair manual advises you to run vinyl hoses from the two bleed valves up to the inverter coolant reservoir which is mounted on the side of the inverter. Then make the car IG-ON periodically and try to get air out of the system by opening and closing the bleed valves.

Check techinfo.toyota.com for repair manual info including the air bleeding sequence recommended by Toyota.

When I owned my 2001 I recall that this process took a few hours. When you are done, you should hear the inverter coolant pump sounding like an aquarium pump, you should not hear air bubbling, and when you look at the inverter coolant reservoir you should see a "step" in the fluid level where the very front is higher than the fluid further back in the reservoir.

It is reasonably easy to get air out of the Classic engine coolant loop (unlike 2G) because there is no CHRS system. That process is similar to any other vehicle with a small 4-cylinder engine, you can find drain cocks on the engine block and the radiator. Unlike 2G, I do not believe there is a vent on top of the radiator to release trapped air, but Classic doesn't really need that.

 

The recommended coolant is either Toyota Long Life Coolant which is red and has a service life of 30K miles; or Toyota Super Long Life Coolant which is pink, pre-mixed with distilled water, and has a service life of 50K miles.