MB recommends that brake fluid be replaced according to a schedule. My question: can a competent technician ascertain that the brake fluid does not need to be replaced simply by inspection and irrespective of the interval since it was last changed? I ask this because, on a couple of occasions, I've asked whether I need to replace the brake fluid and I've been told no, even though it's been several years.

Thanks.

__________________
14 E250 Bluetec "Sinclair", Palladium Silver on Black, 153k miles
06 E320 CDI "Rutherford", Black on Tan, 171k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver, 142k mi, wastegate conversion

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

shertex,

The fluid of greatest concern is in the caliper and the brake lines. If you bother to inspect this stuff, you might as well change it. Brake fluid is cheap, and if you do it yourself every two years you will see the stuff coming out is nearly black. The discoloration is due to corrosion products, mainly, which are not coming from the reservoir. Change it as the manual suggests. Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

I'll second Jims comments. Just get a Mity-Vac and change it every year (don't wait two, damage is already occurring by then) and use a synthetic dot3/4 compatible fluid (absorbs less moisture than the non-synth.)

__________________
1984 300D Turbo - 4-speed manual conversion, mid-level resto

1983 300D - parts car

1979 300TD Auto - Parts car.

1985 300D Auto - Wrecked/Parts.


=========================

"If you don't know where you are going, any road will get you there". Lewis Carrol

The concern with all brake fluid is the absorption of moisture. After a certain time, the moisture gets to a level that allows corrosion to begin. You cannot tell how much moisture the fluid contains by looking at it. That is why it is changed on a two year schedule.

Moisture in the fluid will cause both corrosion (and sticking, poor brakes) and allow the fluid to boil under emergency braking with loss of braking power and the very worst possible time.

Replace very two years (a project for me this fall, they ALL need it, of course!).

It's easier to change than you think -- fronts will drain by gravity, all you need is some aquarium air pump hose over the bleeder and a bottle to catch it in. install tubing on bleeder into the bottle, open bleeder and add fluid to the master cylinder until what comes out is new fluid. Close bleeder, move to the other side and repeat. If you can reach the rear bleeders with the car on the ground, this may work on the rear as well. Easy enough, and you can buy a lot of brake fluid for the cost of new calipers!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

The reason I think most tech's say this is because none of the Japanese or American manufactures say you have to change it. It is worth every penny of the $10 it cost you every two years. I will do mine every spring, I want good brakes. It also give's you a good chance to go over the braking system.

__________________
1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

It's way easier than that if you invest $30.00 in an Easibleed. Install the easibleed and go around and crack all bleeders, one at a time, and you are done. You do have to be careful to refill the m/c after two wheels are done. Otherwise:

Recipe for homemade brake bleeder. Gotta get one. http://www.peachparts.com/shopforum/showthread.php?t=103226&highlight=brake+bleeder

That's the funny thing about it. It's a well-respected shop that only works on MB, BMW, and Porsche. They really have an impeccable reputation.

__________________
14 E250 Bluetec "Sinclair", Palladium Silver on Black, 153k miles
06 E320 CDI "Rutherford", Black on Tan, 171k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver, 142k mi, wastegate conversion

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

Besides water absorption - which cannot be detected by visual inspection - another thing that degrades brake fluid is copper absorption from the brake lines. This copper replates on other parts of the system. If you have abs, neglect can get very expensive. I believe there are methods of detecting copper (and water) in brake fluid, but for the cost of analyzing the fluid, one can just as easily change out the fluid.

Here's an article that has more detail on the subject: Corrosion in Brake Fluid

__________________
95 E320 Cabriolet, 159K

The greatest concern is that brake fluid WILL absorb moisture from the air.
Moisture in the brake fluid reduces it's boiling point.
If under heavy braking your brake fluid boils, you will be unable to apply enough pressure to that brake circuit to effect any braking of the vehicle.
Replace it every 2 years! - Cheap insurance.

__________________
Tony from West Oz.
Fatmobile 3 84 300D 295kkm Silver grey/Blue int. 2 tank WVO - Recipient of TurboDesel engine.
Josephine '82 300D 390kkm White/Palamino int.
Elizabeth '81 280E, sporting a '79 300D engine.
Lucille '87 W124 300D non-turbo 6 cylinder OM603, Pearl Grey with light grey interior


Various parts cars including 280E, 230C & 300D in various states of disassembly.