Water slush sound under dash on initial ICE startup

If it's a gurgling sound, check your coolant levels. You may be low or have air in the system. There are a number of posts here regarding that symptom. Don't delay, because running your Prius with low coolant could significantly damage expensive systems.

 

I experienced this once when I was a little bit low on ICE coolant. Due to a small water pump leak. Added some more coolant and after a couple drives it was gone. That's just my experience

 

Seems to me you have two possibilities here.

1) You have a leak or somehow rainwater has collected in your car - either in or under your front tray somehow. Perhaps you have a clog. Or the water is elsewhere in the car - it just SOUNDS like its in the dash. There have been numerous instances of water collecting in the spare tire area due to seam weld cracking and leaking. Search this and you will see them.

2) You have a low coolant issue in or need to purge air from one of the two coolant reservoirs. This seems the more likely scenario to me. Even if the levels look good, you could have trapped air bubbles in one of the cooling systems. You can search for this scenario as well.

Reading through those two scenarios for similar symptoms should lead to some insight for your particular case. I know it's not a definitive answer, but I hope it helps.

Like Aaron, I had a low coolant situation in my Prius that caused gurgling. I determined that I had a faulty radiator cap that was allowing seepage. I replaced the cap and topped off the coolant and have not had that issue since.

 

Might also be the air conditioner fluid flowing. Are you running AC when you hear this?

 

I am thinking you have heat on and it is low coolant level...you can have air trapped in there, I think the fix is to add coolant but you gotta get the air pocket out of there and I don;t know how on a Gen3 but Gen2. Where do you live...cool climate I am thinking.

 

Just being a grumpy old man: you do know the sun doesn't rise and set only in the United States of America. Priuschat has members from all corners of the globe. A two letter acronym is a bit esoteric for a lot of them.... Done.

 

The very fact a member doesn't put their location usually indicates they're from the US

Oh and ML, you don't have the monopoly on here for being grumpy

 

maybe you hear the inverter pump.

 

Like London I guess. What do you guys call it: the City?

 

interesting, i have the same symptom in a non-hybrid car.

 

software should require, city, state, country.