First, which reservoir, engine or inverter? Second, is reservoir cap on tight? If engine, once cooled, check the level in the radiator. You will need to remove plastic cover first.
If that system has been serviced lately, it probably was over filled. Give it another day or so. If it is the ENGINE coolant and it has NOT been serviced lately.........that is a sign of: A bad pressure cap. Overheating. A head gasket leak. (That is assuming it is coming out the overflow and not out of a hole in the tank.) This could be critical. You should not drive it much, or at all, until you get it figured out.
It may be because you lost the fan belt that turns the engine water pump and the car has extremely overheated which usually blows the head gasket. Its a bad system as there's no temp gauge in the car and you'll never know you lost the belt and are overheating till the check engine light comes on and motor is toast. Which is why you should replace the fan belt way earlier than the manual says. $7 belt can toast the motor.
Sorry where is the fan belt located? Can you send me a pic? Or diagram Posted via the PriusChat mobile app.
The coolant is spitting out of the reservoir tank next to the big silver box. Posted via the PriusChat mobile app.
By big silver box do you mean the one that is mounted right behind the engine? That would b the inverter module. Are you having any other issues such as Yellow or Red Triangle icons, Check Engine Light, etc.?
No . But I sometimes lose the combination meter . Odometer cluster Posted via the PriusChat mobile app.
Are you talking about the inverter module silver box? Combination Meter has nothing to do with coolant spitting from reservoir.
What is the coolant level in the reservoir? Can you see turbulence in the coolant flow in the reservoir? If not then your inverter coolant pump may have failed.
Its sometimes low but bc its spitting out coolant . I have an empty water bottle connected so it catches any coolant it might spit out . Posted via the PriusChat mobile app.
I've never seen it happen. I just look nude the hood a few days later Posted via the PriusChat mobile app.
You're seeing where coolant is flung onto the underside of the hood?... Your gasoline engine water pump is near death.
Interesting, because that coolant circuit (gas engine coolant pump) is totally separate from the inverter. Reading between the lines, OP must be filling the inverter coolant and then reports within days it is low because it is spitting out coolant. Unless, the OP hasn't filled with coolant, but saw the coolant flung on the hood, then noticed the inverter reservoir was low and drew the incorrect conclusion. OP, have you checked the level of the coolant in the radiator neck (not the overflow reservoir)? Both of these are by the radiator at the front of the engine bay. You need to remove the front cover to get proper access to the radiator filler neck. CAUTION: only remove the radiator cap when engine is cold.
I'm seeing where he says it's the inverter loop reservoir but am thinking he's somehow confused... Could the inverter water pump have a broken hose or a crack in the pump housing itself? Never heard of this but how else could he have coolant from the inverter loop under the hood? Ahh, I get what you're saying! He's filling the inverter reservoir to the cap, not realizing where full actually is, and it's coming out the overflow under operation? Yet the ICE water pump may actually be bad and flinging coolant under the hood. And he's completely topping the inverter reservoir thinking it's the ICE reservoir. I bet you're right. Engine coolant loop is getting lower and lower all the while... Definite maybe.