braking became soft and makes a sound

[trymonlam]

when i was driving up north from DC yesterday, the car is loaded with my summer wheels, along with many pieces of large lugages. i don't know if the weight's got anything to do with it, but the brake became very soft.

the brake used to be very sensitive. a slight tap would affect the speed instantly. but now i need to really step in in order to get the same braking, it feels a lot more spongy, and when step on it, it makes this blow off sound that's kinda like the doors opening in star trek... my old jag(94') at home's got the same problem for years, but i don't want it to happen to my 202.

guys, does this sound familiar? any help / suggestions / insights? thanks in advance.

[rollinrealbig]

It seems like you have a Brake line leak somewhere, try taking it to a tech. so they can tell you exactly what to replace.


and dont play around with brakes, if you cant do it yourself, just leave it to the pro's!

[cee28o]

maybe ur brake pads r worn out... when was the last time u've changed them

[mayagman]

Well, if you ever had a stiff brake pedal in this car, that's probably when it was broken. Now that it's soft and unresponsive it seems like your car is working just as designed :P
j/k, I've just never been a big fan of mercedes braking

As the others have said, pad check, leaky lines, bad fluid, or a lubericant of some kind on one or more of the discs could lead to these problems. Lines could be bulging too, without a leak. SS lines are cheaply bought, might behoove you to grab a pair and see how you like them.

[trymonlam]

thanks for all the help, guys.
to clear matter, the brake is not just soft and unresponsive, the point is, i don't have much braking for the car. almsot crashed into someone yesterday on my way back to MA from CT. now she's sitting in garage. i will car dealer in the morning to schedule a check up. i know dealer sucks, but i don't want to drive her anywhere far in this condition. once i know the problem, i can go on from there.
will keep you all posted.
thanks again.

[jnenad16]

could be a booster leak if its making a deep whisling sound, but then the pedal would be harder, not softer than normal. if it sinks, its a possible fluid leak, either external from the lines or the caliper, or internal inside the master cylinder if the piston seals are blowing by.

nenad

[roundeler]

Brakes run on a hydraulic principle. The pressure from a fluid system vs. an air system is much more powerful/efficient. If your brakes become soft you most likely have a leak in your line and/or have air in your lines. Periodically you should have your brakes bled eliminating the air in the lines. Once this is done along the system not having leaks, you should be fine.

Air in the lines can create a soft pedal, similar to when the fluid boils. Again a hard pedal in a vacuum system would aim to a leak in the brake booster. I don't know if the w202 has vacuum or hydraulic though. Regardless, soft brakes = bleed them and you should be fine.

[trymonlam]

i took the car in for the tech to check it out. 2 hrs later they came back and said there's nothing wrong with it. it's just that a recently changed brake pad was a oem one which is significantly harder material than the original MB ones. which gives less braking. but then i was confused since i've driven the car since the pad's been changed and it felt better this. far as what i feel like, this happened on the road.
under what circumstance would air be in the braking fluid? is this a regularly happened thing?

[jnenad16]

Originally posted by trymonlam

under what circumstance would air be in the braking fluid? is this a regularly happened thing?
the brake system is not a closed system, contrary to popular belief. the fluid reservoir is open to the atmosphrere usually through the cap or through a small hole sometimes left at the top of the reservoir by some manufacturers. thus the brake fluid needs to be changed yearly because moisture contaminates the fluid and the braking power decreases. but this opening is usually not enough for air bubbles to create in your system, the air usually gets trapped in the fluid when you replace the fluid or a brake line or the calipers, which is why the system has to be bled everytime you perform such repairs.

nenad