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Water in brake fluid???


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I know this post may not apply to reatta owners in the south, but has anyone ever experienced water in the brake fluid, enough to freeze overnight and give a real "wake-up" the first few times the brakes are applied on a morning around the frezing mark. The two real cold mornings this year, the pedal was rock hard (only for a second) and the car pulled violently to the left.<BR>After driving for 5 minutes or so, the brakes work normal.<P>Took the car to a friends shop, asked him to change the brake fluid (even though he couldn't believe water was the problem). I was there as he cracked open the bleeder to find what appeared to be rusty water pouring out. After removing the line it appeared to have more water. Turns out caliper was also rusted, at least partially seized.(piston would not push back in, had to use huge prybar to break it loose)<P>So finally to my question; How did the H20 get in the brake line? At least on the drivers side, I haven't removed the passenger side yet, for the parts store delivered the wrong calipers(time to call it a day at that point).<P>The accumulator was relaced, and changed back the first time I experinced this problem, so I have now had the same experience twice, once with each accumulator, so I don't believe it has anything to do with the problem. I have read almost all the posts concerning brake problems, and did not find any related to this specific problem.<P>Any help is always appreciated.....sorry for the lenghty post.............Dan<BR>

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OK boys and girls, can you say hygroscopic?<BR>That means it will absorb water. New brake fluid is free of water, but over the 10 or so years that your cars has been in service it has absorbed moisture.<BR>One publication claims that after one year of service, the average brake system contains 2% water. If you live in a high humidity area, that might be even higher.<BR>Besides the obvious problems of corrosion, water in the fluid also lowers the boiling point. One chart indicates that a moisture content of 7% will lower the boiling point to approx. 275degrees F. If you use your brakes hard, that could also be a problem. <P>All these facts combined indicate that the fluid should be changed sometime between 2 and 4 years (depending upon where you live)to keep the moisture content low. <P>With the price of replacement Reatta brake parts, changing the fluid is cheap insurance. <P><BR><P>------------------<BR>Barney Eaton Reatta technical advisor for BCA and keeper of the Reatta database.

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DITTO!!!!<P>Barney said it all for me. This is a very well known, though seldom expressed, condition amongst mechanics. I have my fluid changed every year or two (with a radiator flush and tranny filter/oil change) simply for this reason. Here in Maryland, rust is the devil, and fluid changes are your only ray of salvation! Can I get a amen!?!<BR>Sorry you had to find out after the accumulator prob, but maybe the next person will be spared. LOL

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Guest wally888

Con_1<BR> Just remembered, I think, you were the one who suggested I emphasize flushing the brake system in the article on Tom Jenkins Site. I quoted you at the beginning and the end! <A HREF="http://66.8.158.202/~reatta/brakes.html" TARGET=_blank>http://66.8.158.202/~reatta/brakes.html</A> <BR> I will pose this question directly to others, but while the subject is at hand: Why, after seeing a brake fluid diagram, also at the site, couldn't almost the entire system be flushed by opening both rear bleeders while the system is under pressure (key on)? If possible, then the front wheels could be done manually, eliminating need for anything but a wrench and brake fluid. Might even place a board and brick on the pedal to substitute for a person while doing the rears..<BR>

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Wally and Barney,<P>Remember that he had a failed caliper, which probably means that not only did his fluid absorb ambien moisture over the years, but that he had it introduced directly into the system via the failed O-ring in the caliper. <P>If there was lots of water present (melting snow, perhaps?) then when he let off the brake pedal, the water was directly sucked into the lines. <P>Hope the repair keeps you stopping straight!<P>Joe

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Hey there Wally,<BR>My concern... wouldn't it be a bit on the dangerous (extremely) side to open the system while the vehicle is on? First off, and probably most significant, is the fact that the fluid is under pressure in access of 2600psi at certain points; 800 psi at the minimal. The fluid would become a highly toxic, acidically corrosive jetstream, and I suspect, would be hard to properly contain. Secondly, you increase the chance of introducing air into your sealed system; perhaps the single most horrid thing you could do to degrade your braking performance to nil. the fluid flow would be too great to properly replenish. Air is, essentially, the cause of the introduction of moisture into the system in the first place. Without it, there would be no need of a system flush. Simply put, I would highly suggest AGAINST this practice. The time you save would potentially cost more than it's worth. Just my perspective.

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Thanks for all the timely, informative posts. It seems as though reattaman has hit it right on the head. There was not any noticable water in the passenger side caliper, like there was in the drivers side. The seal on the drivers side caliper was also badly damaged , indicating that the large quantity of water in the drivers side caliper was "sucked in", rusting the piston to the point it would no longer return when pressure was released from the brakes(explaining the low pedal I've had since I bought this car).<P>I don't want to suggest for on second that I don't agree with what Barney, and C1 wrote about brake fluid. As soon as I read there replies(they were the only 2 posts as of last evening) it reminded me that a service bulliten BMW Motorycles recently released recommending that<BR> brake fluid be changed annually, especially in the series of bike of which I own. I thought to myself that I have never actually "changed" the brake fluid in any of the 4 wheel vehicles I have owned. Now I realize that just makes me stupid, not only is it necessary preventative maintenance, but, in this case it would have tipped me off to a potentially dangerous situation.<P>The good news is, I just might have the brakes straightened out on this car......might. <P>The bad news is, with my new transmission, this car has cost me $1200 in the past month.<P>And just FYI, calipers cost me $53.42 each. And a "new" water pump was $51.63.

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Wally is correct on flushing the majority of the system using the pump, in fact it is the only recommended way to bleed the rear brakes. The pump used is only a small volume unit and will only build significant pressure when it is contained. If the bleeder is left open just a nice steady stream emerges. The brick on the pedal will probably work but a helper is still a godsend, if only to keep replenishing the fluid as the pump runs. I don't believe the pump would last long if run dry, just like running an in tank fuel pump dry, it would probably score the operating parts.<P>Regarding the brake system diagram: does anyone see how the rear brakes could possibly work if the booster system were to fail. It looks to me like they only work by modulating the boost pump pressure, not direct pressurization from the master cylinder.<P>------------------<BR>Hal, btk@vbe.com

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The manual and a tag on the master cylinder state that silicone fluid is not to be used. I am not sure why this may be, but they are pretty emphatic about it.<P>------------------<BR>Hal, btk@vbe.com

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Better check your shop manual before you put silicone fluid in at least the Tevis master cylinder, not sure about the later model, non-Tevis Systems.

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Check the link provided above by John Chapman. It discusses the advantages and disadvantages of Dot5 (silicone brake fluid.....Thanks for the link Jonn...Dan

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Guest John Chapman

Dan,<P>The following link has some very good general info on brake fluid charateristics and problems. If you follow the links to the home page, there is even more good brake info.<P>I also have a fair amount of data on silicone vs. glycol-based fluids.<BR> <A HREF="http://www.tirekingdom.com/purch/brkfluid.html" TARGET=_blank>http://www.tirekingdom.com/purch/brkfluid.html</A> <P>Cheers,<BR>John<P><P>------------------<BR>John Chapman<BR>BCA 35894<BR>1965 Skylark Convertible (Some Assembly Required)<BR> jmchapman@aol.com

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Good discussion on brakes/fluid. There is lots of knowlegeable people reading this discussion page and their/your, input is really helpful.<P>Tom Jenkins... if you read this, you might like to have a link on your page to the "tirekingdom" site. The information there is very good. <P>------------------<BR>Barney Eaton Reatta technical advisor for BCA and keeper of the Reatta database.

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Guest John Chapman

Dan (et al),<P>A big note of caution here:<P>DOT 3/4/5 specifications <B><I>DO NOT</I></B> indicate whether the fluid is silicone-based or glycol-based. The DOT specification indicates the wet (moisture contaminated) and dry (moisture free) boiling points of the fluid. (For those without a life ( cool.gif ), look up Code of Federal Regulations (CFR) Title 49, Standard 116)<P>You can have DOT 3/4/5 fluid in either formulations. In the US, there is no readily available glycol-based DOT 5 fluid on the market as there is in Europe. The confusion exists because silicone-based fluid is available only in DOT 5 specification on the US market.<P>While there are silicone fluid evangelists who swear by the product (and it may well be perfect in their applications), it has several charateristics that give it nearly the same maintenance requirements as the glycol based fluids. (See BMW motorcycle note in an earlier post)<P>The main drawback is that it is prone to aeration (minute air bubble trapped in the fluid) and the problem increases with use and time. I don't know much about the Reatta brake system, but apparently there is an electrical sustainer pump that cycles constantly to maintain brake system pressure . This would serve to keep any air in the system from coelesing into a bleedable bubble. The results would be 'soft' pedal/ineffective braking, because every time braking pressure is applied, the microscopic air bubbles compress.<P>The second issue is that the silicone and glycol fluids are not compatible, not even a little. In order to convert to silicone fluid with a complex system like the Reatta (assuming the hardware components will handle silicone) a complete system teardown and flush is required. Yep, every nook and cranny, proportioning valve, piston and cylinder. Silicone is heavier than the glycol, so it will remain in any place that is not flushed by flowing fluid under pressure (wheel cylinders, calipers, resivoirs, etc.) From the sounds of the Reatta system, this is not an undertaking to be trifled with.<P>The third issue is that while not hydroscopic, moisture can still get into the silicone systems, only now it condenses and the water settles to the lowest place it can find. Because it won't mix with the silicone, it remains a liquid 'slug' doing all its corrosive dirty work until purged... or heated to vapoization (steam) by vigorous braking where it becomes a compressable gas and helps out the little air bubbles in doing their magic. By now, you'll be rummaging in the back for a Danforth anchor to toss out the window....<P>In short, you'd be trading one set of maintenance requirements for another. In evaluating this issue for my cars, I elected to remain with the low tech DOT 4 glycol. But, my car is frequently driven and not prone to have moisture accumulate in the fluid, minimizing the key benefit of 'non-hydroscopic' silicone fluid. <P>Cheers,<BR>John<P><BR>------------------<BR>John Chapman<BR>BCA 35894<BR>1965 Skylark Convertible (Some Assembly Required)<BR> jmchapman@aol.com <P><p>[This message has been edited by John Chapman (edited 11-08-2000).]

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