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Car Forum / Mercedes-Benz Cars / October 2007breaking fluid contamination problem
hi all, I just went to a mechanic who informed me that my breaking fluid is contaminated and that I need to change the whole breaking system. this is what he did : -he put some of the breaking fluid in a styrofoam cup and visually checked it. after looking at its color and density... he concluded that it is contaminated and it is a disaster. he did not check any of the parts or any cealings in the breaking system. I think someone (from the mechanics I go to) have topped my breaking fluid with steering fluid?? any suggestions on what to do or how can I determine the damage level? Many Thanks Brake fluid that's many years old will be brown so don't let the color make you change all the brake seals etc. The old brake fluid can easily be flushed out and new fluid installed for moderate cost. Get another opinion.  Signature© 2007 T.G.Lambach. Publication in any form requires prior written permission. I think you need to find another mechanic... all you need to do is flush the brake fluid... very common practice and should be done every two years. If he is trying to trick you into thousands of dollars of repairs... he is a crook. > I think you need to find another mechanic... all you need to do is flush the > brake fluid... very common practice and should be done every two years. If > he is trying to trick you into thousands of dollars of repairs... he is a > crook. I guess the question is whether it really is contaminated with anything to begin with. Do you have any reason to believe anything other than brake fluid was put into it? As others have pointed out, if it's just very old brake fluid, it will turn darker over time. When the guy said the whole braking system needed to be changed, did you ask him exactly what he meant by that? In defense of the mechanic, if he good reason to believe it was contaminated, the way liability works today, I could see where he might want to be overly cautious regarding recommendations. If someone came in with a system full of water and God knows what else, and all he said was change the fluid, I could see someone later having a brake lock up, accident, sue the guy, etc. If the brake system is otherwise functioning, OK, I'd just flush it. How well you need to flush it would depend on whether it was contaminated with some other material. If it was, then I'd probably pull the calipers, force the pistons all the way in, to get all the old crap out. Just trying to use the bleed screw, IMO, is fine for replacing fluid, but if it was contaminated for sure, then I'd want to get it all out. Tiger schrieb: > I think you need to find another mechanic... all you need to do is flush the > brake fluid... very common practice and should be done every two years. If > he is trying to trick you into thousands of dollars of repairs... he is a > crook. Depends. If the break fluid was mixed with water and detergents through a rotten brake fluid container cap by a high pressure motor washer you have to replace everthing made of rubber in the brake an clutch system. SignatureRoland Franzius thank you all for your helpfull suggestions. well the color of the breaking fluid is red the same as the hydrolic steering wheel fluid (so I guess someone mixed it and it may have been there for a long time). also the breaks are not functioning normally I think because one of the calipers is hanging. So how can they determine what to change or fix in the system (whether all or some of the rubber ceiling, calipers etc.. )? my guess would be to bleed the fluid first and see how it goes.. did not work then change the deffective caliper.. if not probably dump the car... Any suggestions of what to do??? does anyone know if the steering wheel fluid can damage the rubber in the breaking system (well i guess it is not water (or some other oxidated chemical) it still should preserve the condition of the parts in the system).. thank you for your help in this odd case. >Tiger schrieb: >> I think you need to find another mechanic... all you need to do is flush the [quoted text clipped - 5 lines] >a rotten brake fluid container cap by a high pressure motor washer you >have to replace everthing made of rubber in the brake an clutch system. nino via CarKB.com schrieb: > thank you all for your helpfull suggestions. > well the color of the breaking fluid is red the same as the hydrolic steering [quoted text clipped - 14 lines] > > thank you for your help in this odd case. A MB service station should be able to let perform a chemical fluid analysis. If it contains a liquid like windows washer detergent letting gaskets expand and you have to replace all gaskets and hoses. Otherwise one should at least demount main caliper, brakes, press out the pistons, clean everthing and flush the system twice. A not so difficult to DIY. Unfortunately in German http://amg-owners-club.com/info/technik/technik1.htm at B/ Bremsflüssigkeit: Even small amouts of mineralic oils can destroy the elastomers used. Contamination of brake fluid is not a joke. SignatureRoland Franzius >> Tiger schrieb: >>> I think you need to find another mechanic... all you need to do is flush the [quoted text clipped - 4 lines] >> a rotten brake fluid container cap by a high pressure motor washer you >> have to replace everthing made of rubber in the brake an clutch system. There is a much easier way to change out your brake fluid than getting a helper to help you. I actually just did this a few days ago on my Subaru. All you need is a container, and a short section of clear hose available at any hardware store or aquarium store. Just jack each corner up, take off the wheel, open the bleeder screw and put the hose on, then put the other end in the container, and get in the car and pump about 2-3 times. Get out and look at the hose and note the color of the liquid. Go top off the master cylinder with new fluid and note the color of that fluid also. Now pump the pedal to the floor about ten times for the front brakes, and about 20 for the rear brakes, all the while watching the level in the master cylinder and topping off before you hit bottom. In my 300D I can safely go 15 pumps or so without topping it off. Go check the clear hose and see if new clean fluid is coming out. If so, tighten the bleed screw and move on to the next wheel. If not, then pump another 5 or so pumps and check until you get it flushed. I developed this method with my neighbor, a mechanic of 37 years after I had shoddy performance with a vacuum bleeder that I had just spent 55 bucks on. Actually it was mostly his idea from a similar method that I use to bleed brakes, which requires less pumping, but a helper to monitor for air bubbles. With the vacuum bleeder I kept thinking that I was getting air out, but the air was actually not in the caliper, it was leaking around the outside of the loose bleedscrew into the space under the bleedscrew, then coming up through the bleedscrew. I knew something was up when it seemed that I had gotten a cup or so of air out of the caliper. Keeping the system pressurized by pumping the fluid out doesn't allow air to enter. I was able to do all four wheels of my Subaru this weekend in about a half an hour using the crappy jack that came with the car. Not possible to mix, it was not meant to be mixed with anything, unless someone injected wrong fluid into it. Find another mechanic, I've done this before on my own successfully. It's an wasy job. > Tiger schrieb: >> I think you need to find another mechanic... all you need to do is flush [quoted text clipped - 7 lines] > a rotten brake fluid container cap by a high pressure motor washer you > have to replace everthing made of rubber in the brake an clutch system. I always change the brake fluid annually in all my vehicles. You can feel the difference in the way the brake pedal feels when you do so. The brakes are solid and responsive like a new car always when you keep the brake fluid renewed. Brake fluid absorbs water over time and gets other contaminants and degrades and gets dark and discolored, so it needs to be replaced on a set schedule like changing the oil in an engine, only it depends on time more than miles driven. It doesn't matter if somebody put automatic transmission fluid in. Don't worry about it, just flush the system. Never mind what anybody said about the rubber getting damaged from a contaminant. It is hard to find anything more corrosive and damaging to rubber than brake fluid and the system is designed to withstand that stuff so tranny fluid will never hurt it. You can bleed the brakes using a hand vacuum pump with just one person, but the best method is to have two people. Get an assistant (girlfriends are great for this one). Have them inside the car. Instruct them that "down" means push the brake pedal to the floor and hold it there until you say "up," and "Up" means take your foot off the pedal and rest for a moment. You go to the furthest wheel from the master cylinder first, probably the left rear. Have the car jacked up and the rim and tire removed where you are working. Put the car on blocks, don't just depend on the jack, that would be very risky in any case, and especially when someone is inside the car pumping the brake pedal. You remove the rim and tire because then it is a lot easier to get to the bleeder valve on the wheel cylinder. Remove the rubber dust cap on the bleeder. Attach a plastic hose if you have one and put the other end in into a jar or something (empty brake fluid cans are great). On my 300 TDT the bleeders are turned with a 9 mm wrench. You have to put the wrench on the bleeder before the plastic tubing. If you don't have plastic tubing, get a plastic cup and just hold it so most of the fluid squirts into it. Wear plastic gloves. Have your assistant ready in the car. As you slowly open the bleeder say "down." Fluid will squirt out. Then, close the valve, and then say "up." Don't say "up" until the valve is closed sort of tight. You make it very tight only at the end, but don't ever reef on it, just good and snug is right. Repeat the pumping until the fluid runs clear and is the same color as the new brake fluid as it comes out of the bottle. You have to keep adding brake fluid to the master cylinder as you go. Watch the level carefully because if you pump out all the fluid you will have to sort of start over to get the air out of the system. Monitoring the level of the fluid in the master cylinder reservoir can be a bit tricky because the fluid reservoir probably has two sections and it is easy to think they both are full when only the front one is. Watch carefully and you will see what I mean. Use a funnel so you don't spill any brake fluid because it removes paint. Tuck a rag under the reservoir in case some drips. And keep everything clean. A small bit of dirt will cause a lot of damage over time. As long as you keep the master cylinder topped up you won't get any air in the lines using this method. Work your way around the car repeating this for each wheel, ending up with the left front. This should be done annually with all vehicles, and is called for on the standard maintenance schedule of my 300 TDT, which is how I learned it was a good idea, and I do the same now on my Toyotas too, and I noticed a big improvement in the Toyota brakes the first time I did it. Paul Fretheim >I always change the brake fluid annually in all my vehicles. You can > feel the difference in the way the brake pedal feels when you do so. [quoted text clipped - 65 lines] > > Paul Fretheim Wow.. thanks Paul for trying to help, lots of typing. I do know how to replace the brake fluid, I've done it before, but I do not think it's necessary to replace it every year because oil usually stays clean if there is no leak in its system. The core of the brake problem is, every 1-2 years, air got trapped inside the oil pipe, bleeding out trapped air will boost the brake performance. I usually get together with my brother, and we helped each other. Mike But there IS a leak in the brake system. All of them have vented caps. Moisture enters the hole. Brake fluid is hygroscopic. That means it absorbs water. It will absorb water out of the air. > >I always change the brake fluid annually in all my vehicles. You can > > feel the difference in the way the brake pedal feels when you do so. [quoted text clipped - 75 lines] > > Mike |
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