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question about old old brake fluid color

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nevets

nevets

Jedi Knight
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I finally bled the brakes & replaced the brake fluid in my BN6, using the EZ bleed gizmo...all went smoothly (thanks to information gained from wise ones in prior posts on the subject). The old fluid was quite dark in color, especially the fluid expelled from the rear wheels. In reviewing Norman Nock's Tech Tips, he states that if the old fluid is dark it indicates deteriorated hydraulics and the need for a complete rebuild of the brake hydraulic system. Is this true? BTW, N. Nock also discourages the use of any pressurized brake bleeding apparatus...so maybe he's also mistaken about the color issue? Also, this was my first replacement of the brake fluid since I owned the car...11 years but only 5k miles.
 
IMHO recommendations to change brake fluid every couple of years seems like overkill. I hate to admit it, but my 1982 Chev pickup stops just fine with 24 year old brake fluid. Maybe I should at least consider changing it. As for the dark color, the brake fluid probably picks that up from deteriorating rubber, hoses or seals. If you haven't changed the three brake hoses (2 in the front, 1 in the rear), I would do that. Have you noticed any fluid leaking around any of the wheels? Do you have normal pressure when using the brakes or is the peddle soft? Answers to those questions may lead you to rebuild the front calipers or rear cylinders.
 
Very dark brake fluid can be caused by deteriorting rubber lines, rubber seals, rust, moisture or combination of. Just because brake fluid gets dark does not mean it won't still be good. There are testing strips that can be used to evaluate the moisture level of the fluid. But very dark fluid would make me wonder about the condition of the seals/lines/cylinders and the only way to really know would be to start pulling things apart and inspecting the parts.

I've read that pressure bleeders can introduce small air bubbles into the fluid unless you have a high end bleeder that uses a bladder to keep the pressure separate from the fluid. I've always set the pressure to 10 psi on my EZ bleed to try to minimize this. I've never seen any evidence that air is getting into the system such as foaming or having a soft pedal so I think the lower pressures help in this regard. I suppose one could McGuiver a flexible bladder from a condom or balloon to keep the fluid and air from impregnating each other /ubbthreads/images/graemlins/grin.gif

Cheers,
John

p.s. I know there are plenty of vehicles out there with their original brake fluid but something to keep in mind is the Healey brake system has one system for both front and rear where more modern cars have a separate hydraulic system for front and the rear. So if you lose the brake fluid for any reason on the Healey, you can lose all brakes with only the ebrake left to stop you. Bottom line .. everything in the brake system should be in tip top shape to be safe.
 
I did the fluid replacement as a precaution, not because I was experinecing any degradation in brake performance. Car has firm pedal, no leaky wheel cylinders, etc. I just wanted to know how concerned I should be about the old brake fluid color? I am not very enthusiastic about tearing down the hydraulic system just to find out if there is something amiss.
 
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I am not very enthusiastic about tearing down the hydraulic system just to find out if there is something amiss.

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Hi Steven,

I don't blame you. Without tearing anything apart you can scrub the three rubber hoses with soap and water and take a good close look at the condition of the rubber. Get out the magnifying glasses and flex the hoses. If you see any deterioration of the rubber they are overdue for replacement. Not a bad time to check the rubber section that connects to the slave cylinder. To check the brake system you can push on the brakes a few times as hard as possible while sitting still (stand on them as they say) to make sure they will hold up in a panic stop. It's not a bad habit to do this little test often. Keep the fluid level to the bottom of the threaded area of the cap so when you check the fluid you can easily see if it has dropped any. Fortunately, most of the time brakes fail gradually and give some indication that they are losing fluid or seal pressure. (I'm sure most of us have been in at least one situation where pumping the brakes was necessary to get full pressure). For those other times it's good to practice using your ebrake

/ubbthreads/images/graemlins/driving.gif

Cheers,
John
 
I like noninvasive diagnostics..I'll check the hoses as you suggest and do the panic stop test too. And I'll look into those test strips Keoke mentioned, though with fresh fluid, I have to assume the fluid is ok now. Just to put this in perspective, when I bought the car in 1995 the entire brake system, inlcuding steel lines, were all new. I don't drive it much so it seems reasonable to expect that the brake system should still be ok. Thanks for your input.
 
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And I'll look into those test strips Keoke mentioned,

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Nevets, I am not Keoke, though I will consider it as a compliment.

BTW, the "HELP" #42072 master cylinder cap gasket, with it's pin hole sealed, will do wonders to keep moisture out of your brake fluid.
D
 
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