Brake fluid separated??
Thread Starter
Racer
Joined: Nov 2001
Posts: 392
Likes: 6
From: Churchville PA
Brake fluid separated??
Tried bleeding the brakes last night to fix a low pedal and the fluid was separated with darker/cloudy fluid on the bottom and crystal clear fluid sitting on top. I thought it was water at first so I dipped my finger in and it was actually brake fluid. When I poured some fresh fluid in for bleeding, the MC looked like I poured vinegar into oil with a bunch of small oil bubbles in the vinegar. It then separated again and rested with the clear on top.
Planning to buy fluid today, syphon and replace all that's in the master cylinder and then bleed out the rest through the bleeders.
Any idea why it's separating? Will bleeding it all out clean the system enough? Also, is it safe to assume this is the reason for my low pedal? It stops great and the pedal is hard but, not hard until the lower 1/2 of the pedal motion.
I've only had the car a little over a year and not sure what fluid was in there before. Would this happen if the PO used DOT5 and I just added DOT3?
Planning to buy fluid today, syphon and replace all that's in the master cylinder and then bleed out the rest through the bleeders.
Any idea why it's separating? Will bleeding it all out clean the system enough? Also, is it safe to assume this is the reason for my low pedal? It stops great and the pedal is hard but, not hard until the lower 1/2 of the pedal motion.
I've only had the car a little over a year and not sure what fluid was in there before. Would this happen if the PO used DOT5 and I just added DOT3?
Race Director
Joined: Sep 2001
Posts: 10,560
Likes: 439
From: Wellington, FL
St. Jude Donor '11 thru '25
Do you know how old the fluid is? As a general rule, it should be flushed (replaced) every 2 years or so. Just bleed it out of each wheel caliper until it comes through clear and then see how the pedal feels. Brake fluid takes on water over time which reduces braking ability. I use DOT 4 which has less propensity for water. 
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
DOT 3 and 4 are Hydroscopic liquids that are alchohol based and they do absorb water over time. You have the right plan, syphon it out or soak it out with a rag, then refill and bleed.
I am a big fan of DOT5 ever since my first brake fade caused me to impact the back of a pontiac on my bike at about 40mph, it takes a little care to clean, flush and bleed, but IMHO worth it.
Once its in there it will not give you any problems
I am a big fan of DOT5 ever since my first brake fade caused me to impact the back of a pontiac on my bike at about 40mph, it takes a little care to clean, flush and bleed, but IMHO worth it.
Once its in there it will not give you any problems
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
Maybe someone installed silicone brake fluid in the system with regular brake fluid already in it. In any event, you will have to purge the entire system and refill with the type of fluid you want in it. If you take it to oil change place for maintenance, you need to tell them which type you put in your brake system. If you paid for "full service" [I thought that meant they just charged you more], they could have topped-off your M/C with the wrong stuff.
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
DOT 3 and 4 are Hydroscopic liquids that are alchohol based and they do absorb water over time. You have the right plan, syphon it out or soak it out with a rag, then refill and bleed.
I am a big fan of DOT5 ever since my first brake fade caused me to impact the back of a pontiac on my bike at about 40mph, it takes a little care to clean, flush and bleed, but IMHO worth it.
Once its in there it will not give you any problems
I am a big fan of DOT5 ever since my first brake fade caused me to impact the back of a pontiac on my bike at about 40mph, it takes a little care to clean, flush and bleed, but IMHO worth it.
Once its in there it will not give you any problems
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