8UANEW1

I've noticed that my 2009 IS250 (~35k mi.) has a hard brake pedal when starting... after the car has been sitting overnight or for any prolonged period of time. I'm guessing it could be a slow vacuum leak in the brake booster but wanted to see if anyone else has/had this issue.

Gville350

iTrader: (10)

Yeah, quite a few members AND myself have been witness to this odd event. Thing is, it just happens out of the blue and then vanishes in the same fashion. You'll just have a stronger right calf afterwards. LOL!

kingster

Has only happened to me when I have played around with pedals after installing sport ones and when replacing rotors, brakes. After three, four compressions, I am ready to go. Never after that.
Take it to the dealer and have them check it for you.

seouljahon

iTrader: (1)

got the same thing i just thought it was from pressure applied to the breaks and it fills the line.

Toymota

It happens to my car but I believe it is normal because the brake booster, even with a check valve, probably does not retain vacuum forever (overnight).

You really have to put your back into it to push the brake pedal without power assist. Some people might even mistakenly believe that the pedal is 'locked', because after the first few millimeters of slack, the pedal doesn't move any further with normal foot pressure.

An interesting point is if the engine is at full throttle, say if the gas pedal is jammed, it does not generate vacuum for the power brakes, so after a few pumps of the brakes, the vacuum will be depleted, the pedal will go 'hard' and you may be unable to stop the car (on cars without the Toyota brake override system).

Bichon

Are you sure it is "out of the blue"? I've had it happen two times, but both times followed drives in which the ABS system had kicked in.

Gville350

iTrader: (10)

Yep, completely out of no where. I drove from work normally to Costco. Car sat for 30 minutes. Came out to start the car and the brake pedal was rock hard. Scared me to death; instead of running more errands I went start home because I feared the break booster or master cylinder was going out. Went away after 3-4 days.

accelerate

Anything new on this issue, mine just starting doing this recently

vicsis250

Dam mine just did this today sucks went home thinking I was going to get stuck somewhere