Where do I check the brake fluid on a 580C?

Because when you start it the brake booster will start working, start bleed on wheel farthest from master cylinder and work closer, one at a time pump up and bleed each line at least once after you don't see air anymore...

you need to check the internal leaks of brake master cylinder..it might be rubber inside worn out...

You need to add BRAKE fluid. After that, blead your brakes. You need to find out where the brake fluid went. If there are no leaks, you need to check the remaining life on all four brake sets. If you have no leaks, chances are pretty good that you need new brakes.

First, check your brake fluid levels, if it is low then that enplanes your problem. Also, when was the last time you had the brakes changed? if the are worn down, then this will also cause a low fluid level. if the brakes are fine and the fluid level is good and you still have the same issue, then your problem is probably your master cylinder. Brake boosters hardly ever go bad.

check the vacume line to the braking master cylinder if this lose vacuum the peddle will go to the floor and have poor braking.

Brake pedal goes to the floor? When does it happen. That is the most important piece of information. Most brake systems are power assisted via vacuum from the engine. Your brake booster is what makes the "power assist" work. There are some specific times when you will feel your brake pedal "fade" to the floor and it is normal due to the cycle of the brake components operation.If your brake pedal goes to the floor every time you step on it, stop driving and get to a repair facility! If the pedal is working when driving and the vehicle seems to be working as it always has, then chances are there is no concern. To be on the safe side, have it checked the next time you are in for any other type of service.There is a sensor inside most brake reservoirs that activates the indicator light in your instrument cluster when the level is lower than it should be. As your brake pads wear down, the system requires more fluid so the level at the reservoir drops setting the light. Same thing if there is a leak. The fluid level drops and the light goes on. This brake fluid leak would most likely be combined with a spongy pedal or a pedal fade every time you step on the brakes. A leak would also almost always have a wet area around the leak. Sometimes the leak can be internal to a part of the car you cannot see, so don't count on it.One easy way to check most brake boosters and the brake system for leaks is to turn the vehicle off and pump the brake pedal. Every time you depress the pedal you should feel the pedal "height" come up and the pedal get harder. After a few firm pumps of the pedal, hold it down. Leave pressure on the pedal for 20 seconds or so. Does the pedal move slowly (or quickly) to the floor? If so then there is a leak somewhere in the system. Keeping pressure on the brake pedal, start the vehicle. Does the pedal no drop? It should. That is the power assisted vacuum kicking in as the engine starts to run.The bottom line is that we are talking about your brakes. Your life, your passengers lives and the lives of others on the road around you depends on that system working properly. If you have any doubts, or feel uncomfortable, take it in to have it looked at. Know specifically what it is doing so that you can have your repair facility look at what you are feeling and tell you if

Check the reservoir to be sure the fluid is full. If not, top it off and try it again. If there's still trouble building pressure, pump the brakes a bunch of times, and then check around each wheel for fluid on the ground. If you see none, it's possible that you have a break in the line somewhere through the chassis and that the fluid is leaking out inside. If you see no evidence of leakage, and the reservoir is still full, you need a new brake master cylinder - what will have happened is that the diaphragm around the plunger inside the master cylinder (which moves through the cylinder when you push the pedal, and forces fluid out to the wheels) has a hole or tear in it, so instead of pushing the fluid out to the brakes, the plunger simply moves through the fluid. It never builds pressure, and your brakes don't work.

When you fixed the brakes, did you take the lid off the master cylinder. I just wonder if you spilled out your brake fluid. The only reason the pedal should go to the floor is if the brake fluid is gone or the master cylinder is not working. Check the fuse. Check the brake fluid level. The pedal only goes to the floor if there is no back pressure in the lines between the master cylinder the lines to the brake pistion on the calipers. Please give me a good ratin and keep me informed.

First look for obvious leaks under the vehicle, especially the inside area of each wheel... If you see fluid, you have either a blown cylinder seal or a bad line (check the rubber hoses to the front and back brakes too) Repair the offending part and bleed the air out of the system... (remember to clean pads or shoes if they have fluid on them)... If you see no hint of leakage anywhere, then suspect the master cylinder... if you remove the master cylinder, check and make sure that it didn't leak fluid into the brake booster diaphragm (Brake fluid will destroy the booster)... as in any repair when you open the system (lose fluid), you will need to bleed out the air to restore function... hope this helps...;-)

make sure brake fluid is full. then pump brakes for one minuite check the fluid to see if it went down or stayed full. if it went down then check the system for a leak . if it stays full then you will need a new mastercylender . i dont think you have a vacum problem cause this causes a verry stiff brake pedal not one that goes to the floor