Newbie with Brake Fluid Contamination

[400Magnum]

Hi All,



I was hoping someone here can tell me what is happening to my brake fluid. It seems that in a very short period of time, the fluid in the reservoir will start turning brown and actually get little clumps of fluid apparently gelling and sticking together.



I think my plastic cap is not sealing and allowing air/humidity into the reservoir. Any ideas on how to stop this? I ordered a chromed metal cover to snap over the plastic one, thinking this may help to stiffen it up and prevent it from leaking, but I doubt that it'll help much.



Is it possible to replace the whole reservoir with one of the older ones that had the screw on caps? I never had any problems with brake fluid contamination on my 1990 half ton.



Thanks in advance for any help you can offer.

 

[Bigramguy]

Moisture will not usually cause the clumps you describe,but it may if you have a lot of water in there. I have seen oil in a master,that looked like that. Could someone have put something else in there ? It could also be someone has used DOT 5 in there which is silicone based,and would cause a similar problem.



Either way,a good flush is in order,and replacing the cap\seal would be good insurance. Use a high quality brake fluid,and put any leftovers in a smaller,clean and sealed container as it is hydroscopic and will absorb mositure. I don't believe you can put the 1\2 ton sytle reservoir on,as they are different. I haven't had any problem with the plastic ones as of yet

 

[BK]

400m,



Bigramguy is totaly correct, the brake fluid does absorb moisture over the years. Mine was but 2 years old and it was near black.

Thats a main cause of brake fade and failure. .

http://www.shotimes.com/SHO3brakefluid.html



It's not that the system isn't seal correctly, take a look at a sealed soda bottle that's half full thats been sitting in the sun after it spent time in the cooler. Difference in pressures and temperatures cause condensation.

Depending on where you live, depends on how bad it gets.



You do need to change the fluid in the system every so often.



The clumps could be alge (sp?). There's a lot of natural materials in the system, with the water and other materials, things can grow.



FYI, something I learned, going to Silicone Dot 5 is not a great answer. Since condensation is still a problem, the "water" still gets in the system. Now it wont mix with the DOT5, but it is heavier than the DOT5 and will settle in your calibers and cylinders causing more rust if you dont regularly bleed the brakes.

with the non-silicone based fluids, the water mixes in and doesnt particularly settle in to the lowest part of the brake system.



Silicone fluid must be boiled 1st, before it's added to the system!





I agree with BRG, do a complete flush of the system.



I've gotten tired of the old ways of doing it and invested in a one man system that works great for just this.

Here's a review, premlinary... not done or release yet, of a system I bought and check out and love. .

http://www.tdr4x4.com/reviews/bleeder.htm



It's not cheap, but probably some of the best tool money I've ever spent.

 

[400Magnum]

Well, I thought I replaced most of the fluid in the system about 6 months ago when I replaced the rear shoes and cylinders. I used the regular brake fluid, not the silicone fluid, and used a little MityVac hand held pump to pull the fluid out. I thought it went fairly well as I could see a change in fluid color at all four wheels.



Then just a short time after that, I noticed there was some fluid on the front of the master cylinder, so I wiped it off. When I did that, I realized that the fluid in the master cylinder was very dark colored. I opened the cap, and the fluid had a really dark color to it, and some of the little cloud things forming. I drained that fluid out with a little pump, and filled the reservoir back up. A few months later, repeated the whole thing. And now I'm doing it again.



Maybe I just have a defective cap and need to replace it? It just seems like something is wrong here. I mean, I've had brake systems that I didn't have to touch for years because they were fine. This one doesn't even last for more than a few months before it starts turning dark and cloudy. Or is that normal for these trucks? I don't use the truck hard either, it's a daily driver that is unloaded and I hardly ever go over 70 mph, typically I do around 55-60 mph.



I may take the truck to someone and let them do a complete pressure flush of the system instead of my little vacuum pump method, see if it lasts longer. Maybe I just didn't get all the old junk out and it's continuing to contaminate the new fluid.



Thanks for the advice and replies!

 

[BK]

The little hand pumps can do a complele job of bleeding. But I don't think you can build the velocity up in a continues stream of fluid to help clean the lines.



I 1st suck the master cylinder dry. One my 99, that means I can get 99% from the front 1/2 and about 75% from the rear half.

But the "scum" still lines the master cylinder housing and all the brake lines. I can't clean the rear half, since there is a dam(n) wall between the two, with a small slit near the bottom and top of the wall. so I can drain and fill it, but cant really completely drain the rear 1/2. so that rear half gets dark looking after a while, even though I've power bleed it since a fine layer of scum lines the interior that I cant get to.



It seems that you need to flush the system for a while to help clean or break up the crud from the brake lines and other components... can't out right scrub them, so running clean fluid through them at some velocity for a while is the best you can do.

Then at every oil change, I vacum out the master cylinder and replace the brake fluid with fresh fluid. That seems to help get ride of the bit I couldn't completely get ride of.



It's kinda like one used truck I bought. I opened up the valve covers to check thing out. . not as cleaned as I would have liked. Some hard oil deposit build up and such. But after two years of good oil changes every 1500 miles, that engine cleaned up real nice and you never would have guessed that the past owner just followed the manufacture's schedule... . every 6K miles



My wife's Nissan , 4 years old was about as bad as my 2 year old Ram fluid. But than again, her braking system doesnt do the work my Ram does and hasnt sat on the moist humid beach for weekends on end.



I've brought my past trucks in for "power bleeding"... most didn't have the right equipment and the ones that did certainly didn't sit there as long as I would have like to clean the lines out. Hence why I searched out my own system I could use on everything I own.

If you do find a shop you trust, beg them to take time to run an extra quart or two throught the system.



Bob

 

[400Magnum]

I've looked along the length of the truck to see if there is anyplace that is leaking fluid, thinking that it might be the source of where the fluid is being contaminated, and it all appears to be dry.



The guy that I bought the truck from was rather cautious about what was put in his truck so I doubt that there was anyone that did put anything bad into the brake system.



I recieved the master cylinder cover the other night, somewhat disappointed in it. It's only chrome plated plastic, I was under the impression it was going to be chrome plated metal. I haven't installed it yet because I doubt that it'll do much to help stiffen the cap to seal it, if that is even the problem, which I'm not sure of.



Oh well, I guess I'll try to find a reliable shop with a pressure / vacuum bleeder and coax them into running extra fluid through the lines just to be sure the system gets flushed thoroughly.



Thanks for the input, I really do appreciate it.

 

[MidwestMotorman]

check seal

Could you have sucked in some power steering fluid from the power assist? You could have a bad seal and some power steering fluid sucked in from the hydraboost. That would be my first guess. Check your power steering reservoir and look for contamination there too.

 

[400Magnum]

Power steering fluid

Hmmm, what would I look for in the power steering fluid, the same brownish color and the little dark cloud-like formations?



If the seal was bad and leaking from one side to the other, wouldn't the fluid levels in either the power steering or the brake fluid reservoir change? I was thinking that if I checked and marked the exact fluid level of both, and then checked it again in a few weeks and the levels had changed, wouldn't that indicate a leak somewhere?



Where are these seals? If they are easy enough to replace, maybe I should change them anyway and try it.



I was also told that I might try to seal the cap to the reservoir better by applying some silicone sealant around the seal lip, letting it set up a little and then installing the cap. If I press in the center of the cap rather easily, I can push it down and hear air being forced out. I would assume that if air can get in that easily, then it'd be easy for humidity from the air to get in too. Any thoughts on using the sealant?



Thanks!

 

[BK]

I would say you shouldnt need too. .



But if you want to try, the way I've made seals in the past with RTV is to put wax paper on the surface I don't want the RTV to stick to. Than apply the RTV to the surface I want it to stick to and than assymble the whole mess... take apart 24 hrs later and remove the paper. .



The moisture also gets there from condensation forming (due to temperature inversions and pressure differences), which happens because it is sealed and there is some air trapped in the housing. Making changing the fluid something that normally needs to be done.



It's interesting about the PS fluid and the seal between. .

Sorry no input, but sounds like a good place to look.

 

[MidwestMotorman]

some more info

If the seal leaked a little you would hardly notice it other than the different colored spots. You can take out some of your brake fluid and add a drop of power steering fluid to it and see if that resembles your mixture. The hydroboost develops whatever pressure your pump puts out. I believe the ps system would have more pressure than your brakes, so if it did leak you would only see it in in the brake reservoir. If it did leak you should see other signs of seepage from somewhere around there. Either on the cowl, around the master cylinder, or inside the cab.



I do not have a parts breakdown, so I could not tell you exactly how it functions. It might also be designed so that it would leak externally before getting into the brakes. I would completely flush your brakes first. Otherwise your might be changing your wheel cylinders and calipers in the near future. Once the fluid is changed, you would definitely notice any further contamination. This would be the first thing I would do.



Good luck.

 

[Bigramguy]

I don't think the P\S fluid can get out that easily. There should be a seal on the hydroboost unit to keep the P\S fluid in,and a seal on the back of the master for the brake fluid. Other wise you would make a huge mess trying to change the master cyl. If the hydroboost unit was leaking,it would probably leak out in between the two,and would be visible,before it would ever get into the master cyl.

 

[Bigramguy]

I also wouldn't recommend sealing the cap to tight as it must be able to vent. As the brake fluid is displaced into the calipers,the cap will vent air into the master,ont he top side of the big rubbew bellows\gasket. The rubber bellows will move down and keep the air away from the fluid. The noise you hear when you push down on the cap,is the air being expelled from above the rubber seal. Also,the cap needs to vent to release any pressure buildup when the fluid gets hot.



I would double check the condition of the rubber gasket,make sure it is seating squarly on the resivoir,and replace it and the cap,if in doubt.