Brake flush every two years?!
 

Seems there are concerns over replacing the fluid only. I'd hate to enter a discussion on the recommended 2 years for replacement of flexible rubber brake line hoses. These are a greater concern in that they tend to harden and crack when they get old. They live in an area where they get hit by rocks and debris. Over time relatively new (2 yrs or more) the hoses actually swell under fluid pressure and dramatically reduce braking efficiency.

I'm happy with replacing the fluid, it's the cheapest option when it comes to brakes.

Re: the deterioration of rubber brake hoses.
I remember reading " somewhere"--I think it was in " Cars and Parts" ( a mag for the auto restoration crowd) about this. I think it was in the runup to their frame-off restoration of and 1955/56 Ford Crown Vic. They were discussing the decision to trailer a car that old, ( this was when the car was about 40 years old) as some restorers buy a car that looks good, and drive it home. They remarked that the brake hoses were very cracked, and would, of course, be replaced. Upon removing the hoses they took them to a place where they could be tested to destruction and were amazed that they burst above their original design spec. Not an argument for using old, cracked hoses, ---just information on how well designed are the brake systems ---even in old Fords--admitedly, one of the "low-priced three".

New brake hoses for most Mercedes are less than $50 for all four. From what I've personally seen, it's a good idea to replace them as preventive maintenance every 10-15 years, and they're definitely overdue by about 20 years. I don't understand why people want to be so frugal in an area that would have such dire consequences if a failure were to occur.

BTW, a total fluid replacement requires less than one quart/liter, or less than about $6, even with a good quality fluid like Valvoline SynPower (best bang for the buck, IMO, high boil points and available everywhere).

Both are much cheaper than accidents, body repair, and raised insurance premiums.

:rolleyes: :rolleyes:

WOW, LOL, I can't believe this thread is still alive! LOL :)

I ended up replacing the brake fluid on my car a few weeks ago. Just took it to a buddies house and did it. Relatively quick...

Now, I am going to have to read the whole thread :D I am curious...

I rented a new E-Class in Europe back in 1990 (w/about 2500km). Driving through the Alps, playing chase with a Porsche, was fun. The brakes got hotter than hell. The light came on a few times and they were a little soft, but still worked fine. I imagine that in Europe you would want to change the fluid every 2 years or more often. In the US, it makes sense to me to change every 2 years also. You may want to extend the change based on your driving habits, but I wouldn't go to long. MB engineers probably know what's best for your car.

Todd

Every 2 years is fo the newer cars.
 

My 1985 recommends changing, yes changing the brake fluid every year. Bleeding is specified at 80 cc per caliper, changing is 800 cc fluid per caliper (Starting at the furthest...) I have a cool pressure bleeder and change the brake fluid completely every spring in about 1.5 hours by myself and consume $20 for four litres of fluid. I heard that the fittings and hoses can allow the fluid to absorb moisture and the newer ones are better so 2 years is okay. I don't know but when I change the fluid I can tell when it goes form a yellowish to clear. I also get a little spurt of blackish fluid when I first open the bleed nipple. I think it is seal material but the brake fluid turns black if it is exposed to moisture. I don't really know but it's so simple for me I just do it. I also change trans fluid at 15,000 miles and P/S fluid and filter every 3 or 4 years. Necessary or waste of resources? I don't know.

I did mine last spring and I was just thinking about when I should do it again. I will do it again in April when it warms up a bit. It only costs a couple of bucks for the fluid and it gives me a good chance to go over the suspension.

please change your fluid !
 

yes it's a great idea to change your brake fluid.
Back in the early 70s we would replace many a master cyl on chevrolets at our shop all around the five year mark.
We would bench bleed the master cyl and install the unit without bleeding the system at all unless the vehicle had air in the system.
Well having loyall customers those cars stayed with us but not the masters
cyls their life ended after one to two years,not as long as the originals.
the reason being is the old fluid still in the system would migrate up into the
cast iron master and rust pit its bore,so FLUSH ALL CARS.
Been their. ddeming calif.

Adjust your stereotypes:

http://www.babcox.com/editorial/bf/bf50412.htm

Mercedes specifies the use of DOT 4 brake fluid. DOT 4 brake fluid is more hydroscopic than DOT 3 and for that reason, industrywide, DOT 4 fluid has a suggested service life of 2 years. The reason Mercedes specifies DOT 4 fluid is that it is higher performance (ie has a higher boiling point) which is useful if you design cars that may navigate switchbacks in the Swiss Alps.

I believe that if you verify service requirements for other cars specifying DOT 4 fluid they will similarly call for replacement every other year. Perhaps the specification of DOT 4 fluid is overkill, but it also represents traditional Mercedes values.

I love that hill on Orcas island. On our honeymoon (which seemed like yestereday :sun_smile ) about 11 years ago my wifge and I were riding a fully loaded (for 22 weeks of camping) tandem bicycle down that hill. We were new to tandems but I had done a bunch of reading and equiipped the bike witha drum brake for the rear whell in addition to the rim brakes. I was glad I did the rims and the drum were very hot (the drum actually smoked a tiny bit) when we got to the bottom of that hill......Chnaging fluid is a good idea, keeps you in tune with the rest of the components of the brakes as well....

MB's recomendation is every year.

My 1993 Ford Taurus with 220,000 miles and antilock breaks has had this flush done about 3 times over the years when I had some other service being performed where the calipers were removed. My 1992 Ford F-150 had the system flushed once about 2 years ago when the steel brake line rotted out and the vehical lost it's breaks. My 1988 560SL had this done the first time by me last year when I bought the car and had to overhaul the calipers because the right one froze up. It may have been done previously but I doubt it based on the amount of sludge built up in the calipers.

The F-150 would not have rotted out if the lines were flushed regularely. The 560SL would have not froze a caliper if the lines were flushed regularely. Then there is the decrease in performance issue that occures from lowereing the boiling point. I have never noticed this lack of breaking performance but I dont push the cars.

My feeling is that 5 years is a suitable interval for most drivers and will give the car a lifetime of safe service.

John Roncallo

Brake Fluid replacement intervals?
 

Some hopefully helpful information from a chemical engineer who KNOWS all about brake fluids.

1) All glycol based brake fluids (not the silicone ones) LOVE to absorb water if given the chance. IF the brake system is airtight--water absorbtion will not happen. The MBZ brake reservoir IS NOT airtight, but has a simple open vent in the cap. This DOES allow moisture to get in and significantly lowers the boiling point of the brake fluid and also greatly accelerates the deterioration of the fluid. Changing the fluid every 24 month is probably often enough unless the climate is really wet or you use the brakes on long hard stops (fast stops from high speed, trailer towing, going straight down 'wildcat drive' in Berkely Ca,etc.

GM, Ford and Chrysler all have SEALED brake fluid reservoirs that have a large 'rubber' diaphragm top seal that will not allow moisture to enter unless the top is removed to add fluid,etc. Thus moisture in the brake fluid is not a significant concern. Fluid changes every 4 years is probably enough for such brake systems in normal use. Lots of hard stops--change yearly.

2) Replacing the brake fluid on ANY car before it deteriorates significantly (either water or oxidation) will likely extend the trouble free life of the calipers and master cylinder to that of the car or >25 years. External dust seals exposed to the atmosphere and such will still have service lifes determined by those conditions. Flexible brake hoses do have a finite life and need to be replaced periodically. A 5 year life is conservative and no ruptures or significant braking performance deterioration should occur in that time. Beyond that is difficult to predict. At 10 years, the polymers used in the flexible lines will have significantly deteriorated and hardened or cracked. There may also be enough swelling of the interior lining to restrict flow of brake fluid, especially in 'panic' type stops when immediate braking is wanted. Normal slow and light brake application may remain unaffected--but the hoses may burst and/or so restrict fluid flow as to cause very uneven brake application and loss of vehicle control.

3) Everyone should periodically (every month,3months, yearly?) test the maximum performance of the braking system to ensure the probable availability of that performance should it be needed. This entails:
a) a test of the ABS system by abrupt hard braking on a surface with poor and uneven braking action (leaves, water, etc) long enough to cause the ABS to run for at least 2 sec. This ensures it works, and tends to flush the fluid inside the performance critical parts.
b) A maximum braking performance test from highway speed (60-70 MPH) all the way down to nearly stopped to check for brake fade or uneven performance. Smooth (not panic type) hard brake pedal application should be used. If any doubt in performance is raised, repeat this rather severe test ASAP--within one minute if possible to avoid letting the brakes cool down. The objective is to PROVE the system is capable of AT LEAST ONE maximum severity stop under 'worst conditions'. You should be able to bring to and hold the tires at the squealing/sliding point (ABS actuating) during this high speed test.
Many 'high performance' brake systems do not get 'used' enough to keep crud cleaned off the rotors and pads and you will find them unstable /uneven or disappointing on the first such test--but quite solid and secure on the second such stop--the friction surfaces being 'burned clean' on the first stop. IF the first stop is 'scary and uneven, but the 2nd is good, its a good idea to recheck with cool brakes to ensure good performance with both hot and cold brake pads/rotors.

Some 'high performance' or 'low-dust' brake pads have unacceptable friction characteristics when cool and WILL NOT STOP Quickly (unable to bring tires to squealing/sliding point) unless extremely high pedal pressure can be applied. Some 'low-dust' pads will fade quickly on the high speed severe stop--even to the point of being unable to bring the car to a complete stop.
c) A maximum speed of application 'panic stop' type brake balance test to ensure all 4 wheels apply at the same time (brake lines & hoses are clear of restrictions) and the car stays stable and straight under this condition. This test can be done at low speeds 30-40 MPH and need only be 1 sec long or less--long enough to see what happens and prove satisfactory stability.


High performance flex likes (teflon lined stainless braid) will last indefinitely unless mechanically damaged.

If the TESTS above are performed on a regular basis, your confidence in your cars brake system will greatly improve, as will your skill level at avoiding an accident. Brakes MUST be there when needed--at ANY time or speed. Neglecting the braking system (not changing fluid regularly or testing their performance) is like playing 'Russian Roulette' and may cost you (or a pedestrian) dearly when you do need maximum stopping power and find it isn't there.

Brake System Performance Testing Update
 

Followed my own advice on brake performance testing . I have had my wife's car (1992 Infiniti Q45a (active suspension) out of service for a week chasing a power steering boost (lack of) --ended up replacing the pump today.

Took it for a test drive (PS works as new now), and brake performance is one thing I check on her car regularly. The right front hose burst!! on heavy pedal application!! :mad: Hoses are only 5 year old not OEM but 'premium quality' well known US brand purchased from O'reilly's, fluid gets changed every 2 years ATE yellow one time, ATE Blue next (both are DOT 4)

Tomorrow its getting a set of Goodridge Teflon/braided stainless all around.:D

My experience .... with lots of different cars
 

I have owned many cars over my 76 years, actually started when I was 18 -- a little late in life. I have NEVER flushed a brake system, unless it happened to specifically need it -- with really old fluid, etc. What I tend to do is add new brake fluid when I do the pads and all seems to be well. I have NEVER had to replace a caliper for any reason -- one cars with 150K or so in several cases. I have NEVER had any kind of braking problem on any car.

I guess my point is that we have a wide range of owners in the forum; some being highly technical and spending time on maintaining their cars to a point I consider really unnecessary -- but they enjoy that, so good. I do believe in changing the tranny fluid every 50K and using the very best oil -- changed fairly often. I use syn in all of my cars, except the 76 450SEL -- in which I use the oil normally used in diesel engines -- which is a high detergent dino oil.

I think most owners neglect their coolant as a rule; just dump in more Afrz when needed and let it go. That is a system that does need more attention than it normally gets and should be kept clean. Otherwise the water pump and other things suffer.

In all practicality, I really don't think brake systems need to be flushed, unless the car has XXXXX miles and the fluid seems below par ... in my case, adding new fluid when I do a brake job -- to replace the fluid taken out for expansion when replacing pads or drum shoes --- seems to work well.
Ben Carter