I have a ratchety / pump noise when I start from a cold start and sometime when I switch from 'Park' to 'Drive'. But NOT when I just pump the brake pedal. The dealer correctly diagnosed the brake accumulator pump. (Note: this is NOT the same as the brake actuator pump 'barking' noise or the coolant transfer pump). My question is: How many have this noise on cold start? Thanks! Marvinh
Mine has done that softly from day one, when I press on the brake pedal before pressing Start. Maybe have the dealer bleed the brakes?
No need, it's normal. The brake actuator is depressurized (a bit, not completely) by the car when you switch off, it has to rerun the pump to bring it back up to working pressure when you press the brake pedal.
Mike, but is it supposed to make ratchety / pump noise that we hear on a cold start? Also if Toyota puts out a TSB, does that mean there could be a problem in the future? Thanks - Marvin
Hmmm. Is there any way to compare it to another Prius? Although I just sold my '04, the boost pump was very quiet in that car, and it sounded about the same as the boost pump in my FJ However, I have heard Prius owners in parking lots power up, and theirs sounded like marbles rattling around in a tin coffee can
How to know how often is normal for this pump to re pressurize? Sometimes Im driving in a straight line and I hear the pump come on pressurizing. As well as if Im sitting on the brake at a light for more than a minute, I will hear the pump come on again
I'm used to hearing mine first thing in the morning, and every few times I brake—the meaning of 'few' depending on various things like how hard I brake, the lining clearance, and so on. In a gen 2, the rear brake lining clearance is adjusted by a ratcheting system, and gets progressively larger until the next tooth clicks over and it's suddenly smaller, then gets progressively larger again, and so on. When the clearance is larger, more brake fluid flows on every use of the brakes, and you can use the brakes fewer times between runs of the pump. How often the pump should run while nobody's using the brakes, I'm used to not hearing it often at all, maybe a few times an hour. How often while sitting on the brake at a light, maybe a bit more often. Taking "more than a minute" would sound reasonable enough not to concern me. You can find lots of threads here where people talk about waiting until the pump is cycling every few seconds all the time before they take any action! I think I'd act sooner than that, but what you've described doesn't sound like you have any problem yet.
