I'm wondering if I need my brakes bled or not. Can someone explain what sensation (or symptoms) on the brake pedal if they have air in their lines?

I get a pulsating feeling (with the car not slowing down as normal) without being able to depress the pedal as far as I would normally. With the pedal pulsating, I hear a faint clicking noise as if the abs was turning on.

TIA

EDIT: 2001 225 coupe, This happens only once a week or so, both at low or high speeds

 

Air in the lines = mushy pedal. The pulsating you are feeling could be a slightly warped rotor. How many miles on the car? Have you replaced pads?

FWIW, the recommendation is to change and flush brake fluid every 24 months. If you track your car you have to do it more often. I do mine once a year.

 

What do you use for brake fluid? I'm overdue, thinking Super Blue...

 

ATE Super Blue is my fluid of choice. Holds up quite well at the track under heavy braking, no fade whatsoever. You can also use the Gold Fluid interchangeably with it. That way you can see if you have flushed the line completely once the color changes.

 

good info. thanks.

 

http://www.raceshopper.com/ate_brake_fluid.shtml (For future reference/searches).



Race Shopper has both Super Blue and TYP 200 (amber), and they're usually very competitively priced on most of the stuff they sell. (I got my Ferodo pads from there)

 

Bleeding the breaks is to clean the system of contaminants such as air, dirt & grit. Your pedal would have to go down to the floor if this is really bad. Pulsing would often be warp rotors. ABS is always running when you touch the pedal looking for stopping problems. I'm not totally sure about the clicking noise.

 

The rotors I have are drilled... And if they were warped, wouldn't they produce the problem all the time? I bought the car with about 50K miles, and have put 10K on it since. I guess I should get new pads and have the rotors checked, and flush the brake fluid as a first step.

 

the pulsing/shimmy would only really translate into the car when you were on the brakes, and more noticably at slower speeds.

First thing to do is a visual inspection, which, really, you should be doing once in a while regardless. Rotor should be smooth. If you're comfortable removing your brake pads yourself, check them for glazing as well. There shouldn't be any shiny spots on them. If there are, you can remove it with sand paper. Best to wear rubber gloves and a dust mask. Dust mask is because brake pads potentially have some nasty stuff in them you don't want to be breathing, and the gloves are because you don't want to introduce dirt/oils back onto the pads. Contamination can lead to more trouble. Also a good idea to clean your monkey prints off the rotors after working on/around the brakes. Everybody puts a hand on their rotors, and gets them greasy. New rotors come with a thin oil coating on them as well. You really should do a good job cleaning them before you install them.

Oh one last thing, if, like me, you never have brake cleaner around, zippo fluid is an excellent alternative.