Every time I turn my Prius on and off I hear a whirring-pumping noise. I believe this is the thermo coolant pump (please correct me if I am wrong). A couple of weeks ago the dealer replaced a slowly failing 12V battery and replaced the brake discs and pads. Now the whirring-pumping noise is gone! Should I be worried? What could have changed? Thanks, Andy
I believe the pump noise you are hearing is the pump that fills the thermos bottle. The 12v should have nothing to do with the pump noise! Hal
You mean the pump noise I am no longer hearing. That is my question - should it ever stop unless something is broken? Andy
Correct me if I'm wrong.. but I read somewhere that the UK version doesn't have the coolant thermos flask ? The sound you're hearing is more likely to be the hydraulic brake circuit pressure charging up ?
The UK model does not have the thermos bottle, so no transfer pump. Most likely you were hearing the brake accumulator pump. It makes more of a ratcheting sound. If you want to hear it, press and release the brake pedal three or four times. That will use up the brake pressure and force the pump to run. Tom
Well I guess that is why he can't hear it, but he could before the 12V change!!!!I never even notice location! Another 60's moment.. Hal
No not the 12V battery, they also did the brake pads, they probably did the brake fluid as well. There could be a little less movement now in the calipers or some other subtle change that is triggering the accumulator pump a bit less.
It's probably because of both fixes. The 12V battery replacement makes the brake accumulator pump more effective (not trying to pump on low voltage) so it only runs for a sec. or so. The brake pad replacement stopped it because it no longer has to move the pads as far. I'll bet it still "burps", it just doesn't do so for a long period.
Previously I heard the noise after every time I turned the car off (as well as when turned on). That would still be the brake accumulator pump? It's reassuring that the noise going away actually means the car is working better! Thanks, Andy
How much did the dealer charge for disc and pad replacement. I am about to change mine and have sourced all the parts front and rear for £70 and will change them myself. The pads still have about 50% life left but discs are very rusty so will change everything. Mileage 80K.
460 for parts and labour. It's expensive but I don't have the skills or equipment to do it myself... If I pump the brake pedal I can get it to make a whirring noise. Also if I turn it off with the brake pedal pressed. But it doesn't sound quite the same as the noise I was thinking off. So maybe my car was sick for a long time and I didn't know it. Andy
