Brake fluid

[Taaaaaaahoe?]

I was noticing my brake fluid is Super dark in color. I know most normal new fluid is almost clear. Anyone flush out their systems?

On my last car I just did a gravity flush by opening the blead valves on each tire (starting furthest from fill location to closest) while making sure the resivour was always full.

Anyone else done this? does it work on the Tahoe? Or shgould i just leave the fluid I got in there?

 

MIkE

[Black02Silverado]

You can do the gravity flush. That is about the easiest to do. I have the vacuum brake bleeder. It works great and saves a ton of time.

 

I flush mine out at every brake job since I'm in the system anyway. I went and bought the Super Blue Brake fluid. Here is a site to get an idea of what I'm talking about.

 

I like this because you know when your line is flushed when your bleeder bottle turns blue. Althought for you it would be when the fluid returned to a clear state.

 

It is good to flush because it helps keep the boiling point of the fluid to its original specification. Not many bother to flush but for what little time and effort it takes I feel it is a safety issue and worth the time. Brake fluid absorbs moisture over time and that can cause all kinds of problems in todays high tech brake systems. What to they say, "an once of prevention is worth a pound of cure", that not only pertains to your physical health but preventive maintenance as well.

 

Just do not let the fluid go back through the system. Most push in on their calipers when they do a brake job. That is a big no no, because you are pushing dirty fluid back up into the anti lock system and it can cause all kinds of problems. Always bleed through the bleed valve.

 

So you basically empty as much fluid out of the resevior, fill with fresh fluid and then bleed the wheels.

 

[Taaaaaaahoe?]

Good info!

I assume I start from the furthest tire to the closest (to the fluid resivour)

in this order...

Rear Pass. side - Rear drivers side - front pass side - front driver side

 

When I do it, I just attach a peice of hose to the bleed valve, and let it drain into a container. close it off when done and move on, Any suggestions to doing it differently?

 

I'll admit Im one who pushes the fluid back up into the lines...dont think Ill do that anymore!

 

Mike

 

p.s. How much was your vacuum tool? I always thought these were super expensive? whered ya get it?

[JayMan]

My uncle warned me about how old brake fluid gets. That was way back in the 70's when I was a kid. He thought is would be nice to have me crawl under the car and open the brake bleeder screw while he tromped on the brake pedal.

 

It was a good way to learn how to work on cars, and I never got run over once.

 

I flushed/bled my brakes when the truck was about a month old. There WAS some air in the rear brakes! Nasty.

 

I like to flush/bleed once a year. Especially with the thought of dirty brake fluid getting into my ABS valves and motor. Brake fluid is cheap and for the 45 minutes or so it takes to do, very cheap insurance and good Preventative Maintenance.

 

I already have a vacuum pump that I bought way back when folks had vacuum advance distributors and weird vacuum-related problems. It's just a hand pump thing with a brass body and a gage on it. I think I paid $20 for it.

 

I got the brake bleeder adapter at NAPA a few years back. Hook up your vacuum pump to it and it sucks the old brake fluid out. That also cost around $20.

 

You can get very fancy systems that run on shop air - they use a venturi to make their own vacuum. There is a special adapter that plugs on top of your master cylinder to keep the brake fluid topped off while the bleeder does it's thing.

 

Unless you're doing it for a living, I'd stay with the hand vacuum pump and the bleeder adapter.

[Black02Silverado]

Taaaaaahoe,

 

I got my brake bleeder vacuum pump at Auto Zone for $25. It works just fine and is holding up well over time so I think it is worth the cost. Makes the job so much easier.

 

Your correct on to start at the farthest wheel and work toward the front. The True Blue fluid that I use is expensive but I like it so I can see the color change. They also make a gold color to switch back to when you do the flush again in a year or so, or you can just use a good quality brand. I have read a few places that (believe it or not) ford brake fluid is really good quality fluid and for the price a ton of racers use it. Just a little UBI

 

Hope that helps.

[99silveradoz71]

I flushed mine out last year around 36k with no major problems and good behavior since. I would check the bleeder valve screws if you're in a snow area, as the salt did tend to corrode 1 of mine due to the rubber boot not being on snug.

[elgineddie]

So how much fluid are we talking about to flush and refill the entire system? I followed the ATE link and see it's in 1 liter bottles. Great site, too!

 

Thanks!

Ed in Chicagoland

 

2001 K2500 Suburban

[Black02Silverado]

So how much fluid are we talking about to flush and refill the entire system? I followed the ATE link and see it's in 1 liter bottles. Great site, too!

 

Thanks!

Ed in Chicagoland

 

2001 K2500 Suburban

A one liter can should do it, I bought two because I did all three of my vehicles, my truck, 02 Venture and my 65 Impala, which I converted over to power disk brakes. A friend of mine also did his vehicle and just gave me the rest of his fluid because he just wanted to flush his out and I helped him. He isn't into the car maintenance thing but did it with the notion that I would help him. The other benefit from what I have read up on the net is always try to by brake fluid in a steel can. They say it helps it from absorbing moisture better than plastic.

[cyclejerk]

I plan on doing this as well. One question, how can I run the anti lock motor or flush it out? I'm afraid that if I just do the lines and calipers and don't do the anti lock pump/by-pass that it will just get dirty too soon.

Any recomendations? I guess I could jump it out strait to the battery but that might not be good??????

[JayMan]

Good question on flushing the ABS out. According to my Helm shop manual, it's plumbed straight through, so if you flush/bleed a brake, that particular ABS pump/valve gets flushed as well. Unless you already have air in the valve body (See below).

 

Remember on the 2000 Chev/GM, and probably the new ones too, it's a "three channel" system. The front brakes are pulsed individually and the rear brakes are pulsed as a pair. The speed sensor for the rear brakes is taken off the transmission/transfer VSS.

 

I bought a brand new 1992 Honda Prelude SR that also had three channel ABS disk brakes. That system was entirely different! The ABS system had its own reservoir and used an "accumulator" that the ABS pump would top off.

 

Always felt so weird when you would first take off and there would be a strange "buzzzzzzzz" for a few seconds as the pump filled up the little accumulator.

 

You needed a special tool to reach the hidden bleeder screw to purge the old fluid out of the accumulator. The tool was like an oversize screwdriver with a nipple (Don't laugh!) that you would hook a small plastic hose to. When you opened the screw, high pressure brake fluid would gush out the little nipple.

 

It would take me 2-3 hours to flush/bleed the Honda brakes.

 

Unless you had the Honda diagnostic computer to command the ABS motor to pump the accumulator back up, you'd have to purge it, top off the reservoir, start the car, drive it to the end of my long driveway to wait for "buzzzzzzz", turn around, shut it off, purge, etc. Got old very fast.

 

In contrast, the GM ABS system is a breeze.

 

According to Page 5-183 of my Helm shop manual, the regular bleeding method is used to flush the system and will get most of the air out of the ABS valve body. If not, you have to press hard on the brake pedal and use the scan tool to command "Automated Bleed Procedure."

[cyclejerk]

Jayman,

Thanks for the info.

[Black02Silverado]

Jayman,

 

Thanks, that will come in handy some day.

[JayMan]

No problem

 

Have to mention that when Helm makes any reference to "scantool" they mean the OTC Tech2 scantool. I think the OTC Pathfinder and OTC Genisys will also work, but the Helm shop manual uses specific Tech2 menus and screen shots.

 

As OTC is GM Certified and claims to use "GM Certified Software" for the Pathfinder and Genisys, you should be able to pulse the ABS motors/valves if you ever get air into them.

 

For those of you who use Autotap, not sure if that scantool can even access the GM-specific commands.

 

I suppose if you're REALLY patient, just spend the entire day bleeding every last bubble of air from those ABS motors/valves!