Cold brake pedal

When I start my car in the morning when I push the brake pedal Barely stops the car then about a minute later brake works fine

Could this be a master cylinder going bad?
Thanks
2002 accord 2.3 ex

Lose weight...!

Clown

lol

In all seriousness, there's definitely a problem, unless you're using full race brake pads, which themselves need to be hot in order to work well.

Check that your brake booster isn't leaking vacuum. You can try pressing the brake pedal to the floor repeatedly with the engine off. This will become progressively more difficult until it is very hard to press the pedal. It should become easy again once the engine is started. If it doesn't become harder, or doesn't get easier when the engine is started, then the brake booster is suspect.

Regardless, you should have the brake system bled. Air in the brake lines can also do this. There is a dealer service tool for the ABS systems, but it's still reasonable to be able to do it yourself and get acceptable results. If doing it yourself helps, then consider a professional job. **Disclaimer** I've never done a brake bleed for an OBDII equipped ABS vehicle, so my knowledge on the subject is second-hand. I have done brake bleeds in OBDI vehicles, and non-ABS vehicles, however.

Master cylinders usually just leak fluid, which causes air bubbles, which cause problems. If the fluid reservoir is empty or really low, you may have issues.

I noticed that my car idles high on cold days until it is warmed up. Not sure if this is normal, but it does take a little more brake pedal effort to stop it before the idle comes down to normal. Maybe it's just that?

Definitely bleed the brakes until clean fluid comes out. I do mine every year and usually get a bunch of yucky black or brown fluid out before it runs clear.

Never had any issues re. the abs system after bleeding, I just bleed them like I would on any car. Furthest wheel from the master cylinder, then work your way to the nearest.

When the master cylinder went in my old 92 accord, it got worse as under-hood temperatures climbed. In the morning it would be fine, by the time I got where I was going it felt like I had a bleeder cracked. Brake pedal would slowly go to the floor, but with no loss of fluid. My issue was the internal seal in the master cylinder was allowing fluid to pass by.

If your booster diaphragm is torn, there's no reason the problem would go away when the car is warm that I can think of, unless its a super small vacuum leak somewhere that seals up as it warms up under the hood and everything expands a little.

You say when you first start the car it feels weak and then firms up? If there was air in the system or a failing part I would not see it correcting itself and then working perfectly fine. You would normally feel some sinking of the peddle at a red light/stop sign after sitting there for a second it would start to feel spongey if air or that part is failing.

I think what Connie is trying to say is when you have a automatic car and it is warming up, the car tends to "Pull" itself along while in drive until the car hits operational temp and the high idle comes back down ,after that the car is easier to stop because the high idle is not being read as you giving the car gas while in drive.

That should only apply to automatics and not confused with things like high temp pads and or high temp brake fluid which takes a lot more heat to properly function before having a firm peddle/ stopping power and or failing parts/fluid.

Blazinqwickly said:

You say when you first start the car it feels weak and then firms up? If there was air in the system or a failing part I would not see it correcting itself and then working perfectly fine. You would normally feel some sinking of the peddle at a red light/stop sign after sitting there for a second it would start to feel spongey if air or that part is failing.

I think what Connie is trying to say is when you have a automatic car and it is warming up, the car tends to "Pull" itself along while in drive until the car hits operational temp and the high idle comes back down ,after that the car is easier to stop because the high idle is not being read as you giving the car gas while in drive.

That should only apply to automatics and not confused with things like high temp pads and or high temp brake fluid which takes a lot more heat to properly function before having a firm peddle/ stopping power and or failing parts/fluid.

Click to expand...

Thanks, that's exactly what I was tryin to say. I was blazinqwickly this morning. Lol