Sloshing Sound & New Coolant Valve

most likely still have air in the system. need to bleed out the air.

 

yes I would do that. Did you replace the coolant too? You should get all that done together.

 

well I sure hope they did.

In the inverter pump recall, toyota is suppose to change the coolant because the coolant is on the bill. However techs just clamp off the hoses, change the pump. much faster and you won't know the coolant isn't changed.

 

the proper coolant is the "super long life coolant" by Toyota. It's pink in color

 

Gen II Prius (2009) will exhibit the symptom the OP is describing when air is present in the system. When doing the work that was done unless the system is properly purged of ALL the air, the Prius will exhibit the sloshing sound the OP is describing. The fix is to properly purge ALL of the air from the system.

I would check the fluid level in both the overflow bottle and the radiator itself. More than likely the system is NOT full. To access the radiator, the splash guard over the top of the radiator must be removed. Once that is done, you can then remove the cap and inspect the fluid level. If it is NOT full to the top of the neck, then the system does have air in it.

There is a bleeder on top of the radiator that need to be opened when refilling the system. The fix is to open the bleeder on top of the radiator, and then fill the radiator to the top of the neck and also fill the overflow bottle. If you DIY, you will find it might take more than one fill up and bleeding to solve the problem. Also when filling and purging the air, have the heat on HI and the fan on full force. (NO AUTO).

Normally the dealer (stealer) can solve the problem, but not all of them are up to speed on this. Do a google search and read up on what Patrick Wong has posted here on PC about the Gen II and how to properly drain and refill the coolant loops.

As said above, be sure to use the Toyota SLLC when filling the system. Once all of the air is purged, the Prius should operate normally and the sloshing sound should go away. IMO, it is NOT related to the rain in California.

Best of luck to you,
Ron (dorunron)

 

The other alternative that has been mentioned in the past is that the rain gutter drain, below the wind shield, is clogged with debris, and the rains have just made that noticeable. Diagnosis would depend on just where the sloshing was coming from, and how it reacted to turns.

 

If it is the problem nh70 mentions above this post, Water sloshing sound when turning?, has some good information on cleaning out the debris.