Loud buzzing sound when car is on, and rattling when braking?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by MiaTwo, Nov 11, 2019.

  1. MiaTwo

    MiaTwo New Member

    Nov 11, 2019
    Las Vegas
    2008 Prius
    So I have 3 different problems I've noticed with my 2008 Prius I recently purchased.

    1. The car makes a very loud buzzing sound all the time. I've attached a video, it doesn't sound loud in the video but in reality it's VERY noisy. My research makes me think it could be the water transfer pump possibly?

    2. Every time that I brake, and sometimes when driving slowly or even parked, there's 2-3 second rattling sound. It's not too noisy but it's loud enough to be annoying. From what I've read, depending on how bad it is, it could be completely normal, or could be a failing abs actuator?

    3. Driving in the city for about 12 miles, my average mpg is only 38, mostly at slow speeds. Is that normal, or is there reason to think something may be adversely affecting the gas mileage?

    I bought the car cheap ($3600 for a 2008 with 115k miles). It used to be a county work vehicle and was purchased at a public auction originally. There was a crack in the windshield and some minor bumper damage, in case that helps figure out possible causes.

    I'm going to take it to a mechanic tomorrow and have them look at it, but having an idea of what I may be dealing with would help me make a decision about what to do. Are these possible DIY repairs if so for someone with only limited knowledge doing car repairs (Replacing alternators and thermostats and stuff like that on conventional vehicles, no experience with hybrids though)?
    #1 MiaTwo, Nov 11, 2019
    Last edited: Nov 11, 2019
  2. bisco

    bisco cookie crumbler

    May 11, 2005
    2012 Prius Plug-in
    Plug-in Base

    is the a/c on?

    the rattling is probably just normal brake pump sound, have you ever driven a prius before?

    38 could be normal, depending on tires, inflation, hvac use, heavy stop and go, and general maintenance such as air filters, oil level and etc.
  3. edthefox5

    edthefox5 Senior Member

    Jul 25, 2007
    Clearwater, Florida
    2007 Prius
    All I hear is the inverter. The recording was too short. Open the hood and locate the noise. The inverter is very loud on a G2 Prius. Its very loud if the ac is on. Turn off the ac and listen to it.

    Rattling sound may be engine bearing damage issue. Many G2's have been run dry of oil and now damaged that's a very common post because people never check there oil anymore. There's only a few quarts of oil in this tiny engine it needs every bit of it. Check the oil should be at the top mark of dipstick. If not add some. keep it the top mark always.

    The car probably eat's engine oil. Check the oil every few days till you get a sense of how much. You must wait a few hours for all the oil to drain back into the pan before you check the oil as the engine has VVT system that stores a goodly amount of oil in the head.
    Best to check the oil in the am before starting the car.
    keep running the engine with low oil it will be new engine time $$$$.

    Check out the cars service history. Go to toyota.com/owners forum and join. It will require entering the car's vin. The vin can be found on your insurance card. Once joined you will be able to see every visit the car has made to an authorized toyota dealership for service.
    You may see why it went to auction. many a Prius bought in auction head there because the hybrid battery was condemned at the dealer and the owner traded it in on the spot. The dealer then sends the car right to auction.

    If the car has the original hybrid battery the big main battery in the trunk it is of the vintage where it will soon or already show issues especially since the car has not been driven alot. That's the jackpot for a used prius. An expensive hassle if you cannot diy.

    Use the search forums button up top and search

    hybrid battery

    to see what mostly everyone including myself is dealing with in a G2 prius.