PDA

View Full Version : Brake fluid, the facts!


Valentine One Radar Detector

DonTom
10-18-2009, 03:25 AM
I came across this to get the facts (http://www.aa1car.com/library/bfluid.htm) on brake fluid after hearing some say that changing brake fluid is similar to changing the air in your tires.


-Don- SSF, CA

Eric
10-18-2009, 06:29 AM
I came across this to get the facts (http://www.aa1car.com/library/bfluid.htm) on brake fluid after hearing some say that changing brake fluid is similar to changing the air in your tires.


-Don- SSF, CA




Good article!

I am extra fastidious about this service when it comes to bikes. I do mine annually. You do not want to have brake issues of any kind when you are decelerating from 150 mph! (Besides, just "normal" sport bike riding is very taxing on brakes.)

Another thing: In my old muscle car, I use DOT5 silicon fluid, which is very expensive relative to standard but lasts much longer. (Caution: Silicon fluid does not mix with regular fluid. You have to completely purge the lines and every other part of the system before using DOT5.)

Ken
10-18-2009, 06:38 AM
I came across this to get the facts (http://www.aa1car.com/library/bfluid.htm) on brake fluid after hearing some say that changing brake fluid is similar to changing the air in your tires.


-Don- SSF, CA




Good article, Don. I have a feeling we discussed the hygroscopic effects of brake fluid, quite a long time ago, on one of our forums. I have mine changed every two years (maximum) on the car and every year on the bike at the start of the riding season. The Carina brake fluid and coolant were both changed during its last service, a few days ago. My dealer checks all fluids for contamination and effectiveness at each service and recommends when to change them on their routine Vehicle Safety List (VSL). The VSL is a free option that I always go for at each service.

Ken.

chiph
10-18-2009, 04:32 PM
I just changed mine on the Ridgeline. It was 3 years old, so was due.

However, the dealer charged me $139 for this service. They claimed it was because they had special equipment which ensured all the old fluid was out. I'm thinking they're full of crap. A Mityvac hand-vacuum pump is $39. The electric ones do cost more, but they don't do all four wheels at once, and you still have to keep the reservoir topped up to prevent air being introduced.

I think in the future I'll find a friend and bleed them the old-fashioned way. Buying them a steak dinner as a thank-you is a lot cheaper than going to the dealer.

Chip H.

MikeHalloran
10-19-2009, 11:03 PM
....DOT5 silicon fluid, which is very expensive relative to standard but lasts much longer. (Caution: Silicon fluid does not mix with regular fluid. ....

It doesn't mix with water, either. I.e., it's hydrophobic, not hydrophilic.

Which sounds like A Good Thing on its face.

The only problem is, if there's a drop of sweat, or other tiny bit of water, in the system, it will be marooned on the local bottom of the system. ... where it forms a corrosion cell, and eventually eats a pinhole right through an otherwise perfectly preserved piece of iron.

I suggest that you change the silicone fluid at least as often as you would change regular fluid. ... and maybe flush with regular fluid just to get the water out.

Eric
10-20-2009, 06:53 AM
I just changed mine on the Ridgeline. It was 3 years old, so was due.

However, the dealer charged me $139 for this service. They claimed it was because they had special equipment which ensured all the old fluid was out. I'm thinking they're full of crap. A Mityvac hand-vacuum pump is $39. The electric ones do cost more, but they don't do all four wheels at once, and you still have to keep the reservoir topped up to prevent air being introduced.

I think in the future I'll find a friend and bleed them the old-fashioned way. Buying them a steak dinner as a thank-you is a lot cheaper than going to the dealer.

Chip H.

I've heard that with ABS equipped cars, you need special equipment to purge the ABS pump - and this is what adds to the cost, etc.

DonTom
10-20-2009, 09:25 AM
However, the dealer charged me $139 for this service. They claimed it was because they had special equipment which ensured all the old fluid was out. I'm thinking they're full of crap. A Mityvac hand-vacuum pump is $39. The electric ones do cost more, but they don't do all four wheels at once, and you still have to keep the reservoir topped up to prevent air being introduced.

He's probably correct, because of the ABS pump.

In some vehicles with ABS, getting all the brake fluid out is a hassle and very difficult for the average home mechanic without special equipment. And in some cases, trying to do the job yourself can cause you to have a vehicle that has so much air in the brake lines that you will have no brakes at all until you have the thing towed to somebody who can fix it right.

Cars are not made like they used to be. Eric can explain that!

And because I don't want to chance doing it myself, I now let my cars go a lot longer than I should without changing the brake fluid. I won't hesitate to do such a job in any vehicle that does NOT have ABS.

I usually just change as much fluid as I can in the brake master cylinder when I do a brake pad job. But that doesn't do much for the brake fluid in the lines or the pump.


-Don- SF, CA

chiph
10-20-2009, 07:15 PM
I think it's actually OK -- when you hit 9 mph the ABS pump does a self-test, and over time that will cause any old fluid inside it to mix (and get diluted by) the new fluid.

The Mercedes & VW I used to have did not do this, so for those cars you needed the factory hand-held tester to command the ABS pump to run briefly after a change.

Chip H.