Continuous Brake Fluid Contamination

[eagleone1983]

Hey Guys I'm having a fluid contamination issue. So I noticed a few weeks ago my car was pulling to the right upon braking, to the point that it would change lanes if I didn't fight it. Scared the shiz out of me the first time it happened. So I checked my master cylinder and the forward section (reservoir closest to front of car) was milky looking. Rear reservoir was nice and clear purple (DOT 5). So I cleaned out the master cylinder and bled everything until it ran clear purple again, problem was solved drove it for about 30 miles or so. The car sat for about a week or so and I took it out again, same issue pulled to the right just as bad as before. So I pop open the master cylinder and the forward reservoir is milky again, what gives? This is the first summer I've had this issue. All brake lines hard and soft, drum brake components front and rear, and wheel cylinders were replaced in 2012 when the car was finished with it's resto. The booster is new 2012, the only thing I didn't replace was the master cylinder but it's not an original and was replaced sometime by the previous owner of the car but worked fine so I cleaned it up and kept it. Could the master cylinder be the issue? I don't see any leaking anywhere.

 

[Matrix2]

My question is why are you using DOT 5 brake fluid? These old systems (and the usual upgrades) typically use DOT 3 (or DOT 4) fluid (both glycol based), which is not compatible with DOT 5 (which is silicone based). Very few cars use DOT 5.

 

[lewtot184]

i wonder if your fluid is getting aerated. dot 5 will hold and trap air bubbles. a lot of small air bubbles may make the fluid appear milky. look for leaks that could lead to sucking air and could cause the brakes to pull. i've been using dot 5 for decades in my old dodges with no ill effects. it won't eat the paint off or absorb water like dot 3, but it will trap air.

 

[Hemi Rebel]

i wonder if your fluid is getting aerated. dot 5 will hold and trap air bubbles. a lot of small air bubbles may make the fluid appear milky. look for leaks that could lead to sucking air and could cause the brakes to pull. i've been using dot 5 for decades in my old dodges with no ill effects. it won't eat the paint off or absorb water like dot 3, but it will trap air.

X2

 

[eagleone1983]

Okay will do. What's with only the front reservoir being milky though? Is the brake system separated by reservoirs at all? That would help me narrow down my search.

 

[Hemi Rebel]

Okay will do. What's with only the front reservoir being milky though? Is the brake system separated by reservoirs at all? That would help me narrow down my search.

Yes, two channels. Front and rear. The smaller reservoir is for the rear. The larger one is for the front brakes. The one closest to the booster is for the front brakes.

 

[bigmanjbmopar]

x3 on the air getting in

 

[miller]

You say all the brake lines were replaced...

Might have the same problem I had...since fixed. If you replaced the hard lines at the MC, could have the wrong fittings, going into the MC itself.

Originally, when I rebuilt/converted my system, I used most of the fittings. But, could only wire brush 'em, since no plating shops around. Kept rusting. Hell with it, and went looking for new ones. Found out the hard way, some of those fittings are Mopar only. Trying off the shelf lines and fittings, almost impossible to seal right. That could be where your getting air. I found, and changed out the MC end fittings on mine. Problem solved. Just remembered, those Mopar fittings are also for at the brass block.

Just look up Mopar brake line fittings, and you'll see the difference.

 

[eagleone1983]

Awesome, thanks Hemi Rebel. Now I know my issue is going to be with the rear brakes somewhere since the front reservoir is the only one with milky fluid (furthest from booster). With as much as it's pulling when braking I'd have thought it would be the fronts so you've saved me some time there.

Miller, the new hard lines I bought were from Right stuff or the other popular source for hardlines. I didn't make them myself so I doubt that is the issue especially since the car didn't have this issue the first two years on the road. I'd think if bad fittings were the case I'd have seen the issue way sooner. Thanks for the input though.

 

[eagleone1983]

Finally had time to look into this issue. So I pulled the rear drums and the wheel cylinders on both sides had brake fluid behind the rubber boots so I replaced them both. Car still pulls to the right but not near as bad. Is it usual for wheel cylinders to only last three years? They were made in the US so maybe the ones I just bought, made in China, will last longer. HAHA. I didn't have time to check the fronts so maybe the slight pull can just be adjusted with the brake shoe adjustment.

 

[Shorthorse]

Did you buy stainless lines? Stainless is harder than OEM and harder to seal. That could account for the air. However, you would think that if air can get in then fluid should be getting out. Applied brake pressure is very high. Much higher than the vacuum created by releasing the brake, even considering the density of air vs. fluid.
No sure about your car pulling. I've never experienced that from rear brakes.

 

[eagleone1983]

When I pulled the drums the wheel cylinders had a black dust coating that was moist all around it. I do have stainless lines but I didn't notice an evidence of leaking around those lines.

 

[wvmarv]

When you have brake fluid contamination you have to replace any and all parts that are rubber or have rubber O-rings in them. You can rebuild them if they can be rebuilt. Disconnect all the lines and flush them very good with fresh brake fluid before hooking it all back up and bleeding the system to get out any air. Over time it will just happen again if you don't replace everything that is rubber. Any brake fluid that is not kept sealed will absorb moisture out of the air and should not be used. Back when I was turning a wrench for a living we would see this at least a couple of times a year. Sometimes people would get power steering fluid mixed up for brake fluid because they came in containers that looked the same.