Funky brake fluid?
 

I had the water pump in my '85 300D replaced today...old german Mercedes mechanic told me my brake fluid is "contaminated". He said it is some kind of petroleum-based fluid and will eat away at the seals in the system.

I just got this car 2 weeks ago - don't know anything about this fluid in there...what is petroleum-based fluid? Why would someone use it? And, most importantly, can I just flush it out with lots of regular brake fluid? What kind of fluid do folks use here? I have a mityvac so I can do my own brake bleeding.

Sorry about so many questions, but I want to take care of this sooner than later if my brake system is in danger.

anything Dot 4 rated i believe. I use valvoline i believe(though im to lazy to go to my garage at this time:D ) its DOT 3&4 rated and has worked fine for me

maybe he just wants your money... but I wouldn't risk it. bleed your brakes and replace the fluid. shouldn't cost you much. Does your brake fluid look strange?

unless the brake fluid is chrystal clear, I would agree to change it. the new dot four synthetic is what i would recommend.

synthetic but not silicone.

tom w

It's a good idea to renew Brake fluid on a regular basis...
 

Personally, I renew brake fluid on all of my vehicles on an annual basis (more or less)......your Benz will take about a Liter/Quart......I also use Valvoline Synpower Dot 3 & 4.......it's easy, just suck it from your caliper's brake bleeder with your MiteyVac, and most importantly, keep the reservoir topped up as you do this.....I begin at the furthest wheel from the master cylinder......you may get a bit of bleed air from the bleeder screw threads, a dab of clean synthetic grease around the beed screw will stop this....

SB

So the valvoline SynPower brake fluid is a direct replacement for the original ATE fluid? I've just been using that stuff and it seems to work well. I am actually going to be bleeding my system here within the next week or two. Maybe even tomorrow! :D Its right around the time for the "two year flush". ;)

To answer a question, it seems kind of a dark green. I will flush out the system as soon as I am able...I think I will invest in a motive power bleeder though, I read all the posts on brake bleeding where it received several ringing endorsements. Other things being equal, I'd rather do this the easy way.

It seems many mityvac owners have found that tool rather inadequate due to air leaking in around the bleeder valves. Now that I think about it, this happened to me when I used it on my aircooled VW, which is why I haven't used it in quite a while. On the other hand, it will be extremely handy doing vacuum system checks.

Next question - I may put new seals on the calipers - I didn't see much info on that around the website. Does anyone know of a good how-to for this?

I also endorse the motive power bleeder, makes for a very easy job when bleeding brakes. However, make sure the little rubber caps on top of the resevoir are new and still seal good. I found out that mine were dried out and cracked when I bled mine, fluid started rapidly coming out from under them when I pressurized it. :eek: So I recommend replacing them. :rolleyes:

The Motive Power Bleeder ( or any other) works great IF the rubber caps that cover the fluid level sensors on the reservior are in good shape. If not its a bit of a mess:D

I already said that. :D ;)

Crystal-clear or not is meaningless.

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

Yes I have seen cars with other than brake fluid in the system. The only thing green other than antifreeze that I can think of is two cycle mixing oil. Why people do these things with cars is beyond me.
This is all kind of irrelevant though. If changing your own brake fluid out periodically avoids even the required purchase price of one replacement caliper it is time and money well spent in my opinion. The general dirt in there from disolved or worn rubber parts can accumulate to become a real mess. Then there is the destructive moisture accumulation that can do real damage with time.