How Often for Coolant Noise?

I have a 2005 and a 2007 Prius. I just bought the 2007 used with ~140k, and I have only owned the 2005 for about 10 months, so I am a relatively new Prius owner. I have noticed that the 2007 makes the buzz/rattle sound that is the coolant being pumped to the ICE (I believe) far more often than the 2005. The 2005 does it once every 10 minutes maybe. The 2007 does it constantly. On for three seconds, off for three seconds, on for three seconds...

Should I be worried? How often is it "normal" to hear this noise? I've got no dashboard warning lights, the car is driving well and seems to be working efficiently, but it seems odd to me that the engine coolant pump is running so often (or maybe I am just not getting the sound right).

 

The noise from the first ten seconds of the video above is the one I'm hearing, and it's being generated from the same spot. Again, it's constant when the car is on (ready). On for three seconds, off for three seconds. I did the test of repeatedly pumping the brakes to see if that would trigger the noise, no dice. It really won't make this noise until the car gets moving, and then it won't stop. If I pump the brakes after putting the car in ready mode, it doesn't seem to trigger the noise.

The video posts no solution. Is that the brake actuator pump? I also get the "barking" noise every once in a while, thought not nearly as often, and the barking is quite obviously related to the brakes, as it usually occurs when I am fully stopped with the brake pedal depressed.

 

As usual, Patrick was correct. Idiot lights came on yesterday. I'm bringing it to the shop tomorrow, most likely. Quick question, I'm a halfway decent handyman, but I'm doubting I want to take this project on.

I have no access to techstream currently. So a couple hundred extra at least might have to be figured into the diy cost (no laptop either). Also, this car is my daily driver, but I do have an extra vehicle that can fill in for a few days if needed.

Are my suspicions correct, that I should probably just entrust this one to the professionals?

Also, one last q. I heard there's a dealership in CA selling this particular part for much less (+/-$1k) than the typical dealer. Does anybody have any idea which dealer this is or how to locate the best dealer price?

 

1. I'll have it officially diagnosed tomorrow, but it has exhibited all the telltale signs of actuator failure since I bought the car a few months back. I knew it was coming, I was just hoping it wouldn't be this soon. 99.9% certain it's actuator failure, and it will need to be replaced.
2. I've read a seemingly equal amount of success/horror stories from used parts. Sometimes they last a few months, sometimes they last many years. If this were a job I was going to do myself, I would buy used and accept that I might have to perform the repair again soon, but I think I would rather just hand this off to my local Toyota mechanic (not dealer), and hopefully only pay the labor fee once and get a part that lasts.
3. Yeah, I know mini VCI and a laptop would be necessary for this job, and I just don't think it's something I'm willing to purchase right now.
4. I am going to take it to a local mechanic who used to be the manager of a Toyota dealership service department, but has since opened his own shop. I have only worked with him once before, but he gave me fair pricing on what he did (around $70/hr labor, by my calculations). I am interested in testing how well he will do for me on this job and how willing he will be to find solutions for different monetary tiers (used vs new).
5. Thanks for the tip on the TX dealership. I'll check it out. One thing that is confusing about this particular part is that there seem to be a variety of part numbers that correlate to the same part, which brings me to my latest question.

For instance, toyotapartsdirect.com has PN 44500-47141 for the actuator assembly. Same with toyotapartscheap, toyotapartsestore, and my local dealership web site. The thing is that almost all the brake actuators on ebay or on threads in priuschat have PN 44510-47050. But PN 44510-47050 doesn't even show up on any of the OEM parts sites. Did Toyota change the part number due to a fault in the production/design? What is the reason behind the part number discrepancy?