Backing up, grinding noise - Toyota Prius Forum : Prius Online Toyota Forums
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#1 (permalink) Old 12-24-2006, 12:55 AM
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Default Backing up, grinding noise

I was backing out of my driveway today and I put the car in reverse, and the electric was running. No braking while in motion and foot on the accelerator. Should I be hearing a grinding noise? If not, what could be causing it? This is what I think, it's a brake out of alignment and needs to be calibrated.... but which brake? The Emergency brake or the regular panic brake? I notice the engine has dropped off MPG when I 1st got it. I was averaging a little over 60 mpg before the dragging. Also take into account I am only going 3 mph backwards, road noise would be insignificant.
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#2 (permalink) Old 12-26-2006, 12:45 AM
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You never stated what your MPG is now. 60 is quite high, so just about anything can bring it down from there. I often get 60MPG after I first fill up, but it doesn't last long.

I would check to be absolutely sure your parking brake is totally disengaged. It is easy to accidentally set it on to a click or two, which would introduce some drag. It shouldn't grind, but it is possible I suppose.

Unless the 'grinding' you are hearing is the brake accumulator pump operating to maintain normal brake fluid pressure to the system for use when you need hydraulic brakes. If this is what you are hearing, this is normal.
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#3 (permalink) Old 12-26-2006, 11:38 PM
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Quote:
Originally Posted by DanMan32
You never stated what your MPG is now. 60 is quite high, so just about anything can bring it down from there. I often get 60MPG after I first fill up, but it doesn't last long.

I would check to be absolutely sure your parking brake is totally disengaged. It is easy to accidentally set it on to a click or two, which would introduce some drag. It shouldn't grind, but it is possible I suppose.

Unless the 'grinding' you are hearing is the brake accumulator pump operating to maintain normal brake fluid pressure to the system for use when you need hydraulic brakes. If this is what you are hearing, this is normal.
My MPG is 51-53 at best, still pretty good. Before this grinding It would keep at 58-61 very nicely.

I went to press the E brake in and push it to cancel out, still can hear the grinding.

Brake Accumulator, what side of the car is that on, if it's on the right side, I hear the grinding coming from the upper left portion of the car so I'm not sure about that. According to the book, on page 329, it states

"If you hear a squealing or scraping noise while driving, have the brake pads checked and replaced by your Toyota dealer a.s.a.p. Expensive rotor damage can result if the pads are not replaced when necessary."

It sounds like it's definately a brake issue. To be on the safe side, I am gonna take it up to Toyota and check it out before it gets worse.
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#4 (permalink) Old 12-27-2006, 09:49 AM
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Only problem is, Toyota still has a hard time diagnosing Prius problems. Sounds like "rotors" dragging but upper left under the cowl is where hydraulic pump, accumulator and master cylinder is located. To even get a look, front cowl and windshield wipers have to be removed.
As far as the 58/61 are concerned you have got to be living at the top of a hill and never be going home! .......(tongue in cheek)
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#5 (permalink) Old 12-27-2006, 11:10 AM
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Default Could brake pads have gotten rusty enough to make noise?

After an overnight rain I get a grinding noise from my front brakes when applied. It eventually goes away. Because the Prius doesn't use hydraulics as much it takes longer to go away than traditional cars.

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#6 (permalink) Old 12-27-2006, 03:24 PM
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If you want to know what the accumulator pump sounds like, pump the brakes several times while the car is standing (or even off). Eventually the pump will come on to replenish the brake pressure.

That reminds me of another test. Does the grinding only occur if the car is moving, or does it occur if the brakes are operated while the car is standing still? If the sound only occurs when the wheels are turning, that does sound like a problem at the wheels and should be checked out.
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#7 (permalink) Old 12-27-2006, 08:51 PM
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Default Re: Backing up, grinding noise

Quote:
Originally Posted by Hawqis1
I was backing out of my driveway today and I put the car in reverse, and the electric was running. No braking while in motion and foot on the accelerator. Should I be hearing a grinding noise? If not, what could be causing it? This is what I think, it's a brake out of alignment and needs to be calibrated.... but which brake? The Emergency brake or the regular panic brake? I notice the engine has dropped off MPG when I 1st got it. I was averaging a little over 60 mpg before the dragging. Also take into account I am only going 3 mph backwards, road noise would be insignificant.
Does it do this "everytime"? Is your driveway paved? Did it rain the night before? Have you driven the car in the last few days?

Reason for all this is sometimes the brake rotors will get "surface rust" on them and they will grind if you haven't driven the car in a few days. Other reasons are if you have a sand or dirt driveway and the rain will beat sand particles up and into the rotors. happens to me everytime, and it grinds a little then goes away.

Just a few things that have transpired over in armadillo land....

Hey Dan! Whats up?.......I'm baaaaaack...

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#8 (permalink) Old 01-05-2007, 02:33 AM
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Quote:
Originally Posted by HIVOLTAGE

Does it do this "everytime"? Is your driveway paved? Did it rain the night before? Have you driven the car in the last few days?

Reason for all this is sometimes the brake rotors will get "surface rust" on them and they will grind if you haven't driven the car in a few days. Other reasons are if you have a sand or dirt driveway and the rain will beat sand particles up and into the rotors. happens to me everytime, and it grinds a little then goes away.

Just a few things that have transpired over in armadillo land....

Hey Dan! Whats up?.......I'm baaaaaack...
Quote:
Originally Posted by DanMan32
If you want to know what the accumulator pump sounds like, pump the brakes several times while the car is standing (or even off). Eventually the pump will come on to replenish the brake pressure.

That reminds me of another test. Does the grinding only occur if the car is moving, or does it occur if the brakes are operated while the car is standing still? If the sound only occurs when the wheels are turning, that does sound like a problem at the wheels and should be checked out.
To Dan: It's definately moving. Recently I was travelling about 10 miles, and at every red light I would gently press the brakes and when i slowed to a stop, there was that grinding noise. I can also hear it turning to the left. My vehicle is due for a 16k mile tune up + oil change, maybe that will do something to check it out.

To HiVoltage: Yes it happens everytime, yes my driveway is paved, and no it has not rained the night before. I think frost may have something to do with it cause that's all we get. I drive just about every day.

to All:
I think reading some of these posts helped me realize the flaws in which I have been driving. In the beginning I was getting GREAT gas milage between 58-61. Lately I have been more aggressive with the accelerator and it dropped to 46 mpg. I read on here how some drive and applied it back to my driving and my mpg's are climbing. Plus I think the way I was driving affected everything about the car. Treat it nice it'll be nice back, treat it agressive and it'll suffer. I'm gonna let up on it and this should improve milage and clear any problems.
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#9 (permalink) Old 01-05-2007, 07:46 PM
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If I hear grinding when I back up, it's usually because there's a stick in the wheel well... No, not kidding. :::shrug::: If yours is a loud grinding, maybe check for a tricycle...

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