Hi,
First timer here =)

'94 C220 with 124,500 miles on it and when I step on the brakes, the pedal seems soft. IE. it goes down to near the bottom sometime to stop the car, about shy of 1-1.5 inches of the bottom. I do not hear metal on metal when the brakes are applied, so I don't think i need pads or rotors. Anyone have seen this before or have any suggestions? Thanks all!

-G

 

Low brake fluid or maybe air in the brake lines?

 

Where can I find the brake fluid resovoir/tank? Is it possible that it may need a flush and refilled with new brake fluid? Thanks Doug.

-G

 

Look under the hood in front of the steering wheel next to the fuse box. It's yellowish, white colored. Flushing the brake fluid actually did make a big difference in the feel of my brakes. It just breaks down after a while from heat, age, and pressure.

 

So that's the brake fluid. I thought that was the power steering fluid in there...LOL. Thanks for the help Doug. Made an appointment for an oil change after the weekend, so I guess i'll be adding that job on.

How much should I expect to pay? You know how the dealership is...hehe. Thanks again.

 

roll down your windows and come to a hard stop from 30-40... do you hear an audible squeak? if so your brakes might be worn

 

I have done a few hard stops while the soft pedal has occured, and my windows were down. Did not hear metal on metal sounds. Just pedal goes down more than normal...

 

I have done a few hard stops while the soft pedal has occured, and my windows were down. Did not hear metal on metal sounds....

 

The pads could be worn out and you won't necessarily hear anything, the only symptom would be a low brake pedal. Your pads are likely worn. While it's in for service, I'd recommend getting a brake fluid flush, especially with high miles.

 

Shouldn't the pad warning light come on in the instrument cluster? Or is it not that worn yet? I had the brake pads and rotors done last summer. Since then, probably only about 10,000 -15,000 miles... Thanks for the help.

 

If ur pads are really worn down...then the light should come up once u step on the brake... If not, then should just be the fluid problem...

 

Just went to the dealership this morning for the oilchange and they did the fluid change. They also flushed out the entire brake system. Told me it would be a day or two until I would feel a difference.

They told me that due to the mileage and age of the car, the Master Cylinder was starting to get worn out and should be replaced if the brake flush did not take care of the soft pedal. Anyone have any past experience of how much this would cost? Thanks!

 

Ñote that not all cars have warning sensors on the rear so you had better look at them. It is easy. take off a wheel and look at them. 3mm is warning time and 2 mm is limit.

 

I have the same problem with my 1996 C220- If there's a solution, I'd like to know, too. So far, new rotors and pads have helped some, but after 10k miles, it's low enough to bother me, although pads are within spec. Tried fluid flush WNL, and have been advised to change to stainless brake hoses. Is there any pedal height adjustment?

 

It is time for a complete inspection. Just after coming in from a drive of 10 miles, feel each wheel to see if they are hot and thus dragging brakes. If one or more is hotter than the others, then those are dragging and caliper problems are suspect. With motor off, depress brake pedal several times until there is no boost left. While holding pedal down, start the motor and if the pedal rises, the boost system is working. Raise and depress the pedal and sustain it hard. If it keeps going down slowly, there is a leak or the master cylinder is bad. Remove wheels and check thickness of Pads, My front has wear limit detectors, but not the rear. In case of detector malfunction, look to see that there is not less than 3 mm pad left. Replace pads before they reach 2 mm. With some one holding brake pedal down hard with motor running, check brake hoses for bulges, if any, replace all the hoses as the rest will soon fail. Check disc thickness with a micrometer. Minimum front 22 mm and rear 7.3 mm. Check that these are the right specs for your car. Minimums on some cars are stamped on the edge of he disc. If less replace discs in pairs. Look to see that discs are evenly polished by wear indicating uniform pad contact. If rough, have them turned. Check each set of pads that they move freely when the brake is applied and release when the pedal is released by turning the wheel by hand. If they are dragging or binding, then try brake cleaner on the calipers and the edges of the pads to free them. Shake the wheel to help free them. Take out pads and clean with a wire brush if necessary. Put a little copper based antiseize on the backs of the pads and where the back rub against the calipers. If that doesn't work, you may have to replace or over haul the calipers, clean the pistons and bores and put in new seals. Make sure you get seals for 2 pistons for the front and four pistons for the rear and that there are 4 tiny Orings for where the halves separate in the rear calipers. Each piston has an inner seal and an outer dust cover. I have seen cautions not to separate the caliper halves in the rear, but as long as you carefully clean the surfaces, but don't scratch the surfaces and put the new tiny O rings in place, I see no obvious problem. It worked for me. It is tricky to replace the dust covers. Put the seal on the piston. Insert the piston in the dust cover from the rear. Extend the cover past the piston and insert the edge of the cover in its groove. Then push the piston through the dust over. Check that the dust cover is proprly seated on the outside. Check the brake fluid level and color. It should be clear or just slightly yellow. If it is black, that indicates rubber parts detioration, change the fluid Dot 4 and bleed according to instructions else where. If that doesn't correct the soft pedal, then the master cylinder or its moving parts are probably worn. Remove and dissasemble and clean it. If the whole cylinder interior is sound and well polished, you might try replacing just the kit of moving parts, If it is pitted or corroded, and unless you know how to hone and clean it perfectly, it is better to replace the master cylinder. Be very careful to not let any air get into the ABS unit using proper plugs when disconnecting lines. If you let air get in, it may have to go to a qualified MB shop with a power bleeder to remove the air and test the ABS. Before adding clean brake fluid, suck out what you can with a syringe from the reservoir. Then fill with clean fluid. Put a hose on a bleeder and keep the open end under brake fluid while opening the bleeder just barely enough to allow fluid to pass due to pedal pressure. That way you won't get air in the lines while raising the pedal to make another stroke. It takes about a quart to flush the system well. Flush the system manually before flushing with a power bleeder acting at the wheels so as to not push dirt back to the ABS. That caution is not needed when the power bleeder connects to the reservoir. Bleeding order is right rear, left rear, right front, left front. Use jack stands where appropriate. After all is done , in a safe place, test at increasing speeds and severity several times until the ABS is activated to be sure all is well. There should be no chirping tires or swerving. Thereafter remember to replace the fluid every 2-3 years so that the absorbed water is removed to avold corrosion and deterioration of rubber parts.

 

Pedal heigth adjustment is automatic according to Bentley manual. Of course the automatic adjuster could fail. Look at it. Between pedal and push rod. If it is low, you may suspect that there is a ridge of crud in the master cylinder preventing it from retracting fully. Stainless hoses shouldn't be needed, If bulging under pressure, just replace with standard hose.