Flush brake system?

This is one job that I would pay to have done; I don't consider it a DIY job. The fluid gets contaminated with dirt and moisture and, at least on the pre-ABS units, it was a recommended item because it helps to prolong the life of the braking system.

. . . Flush brake system? Group: alt.trucks.chevy Date: Fri, Oct 17, 2003, 9:02am (CDT+1) From: snipped-for-privacy@REMOVETHISpobox.com (Mike=A0Copeland)

I noticed on another thread where someone was overcharged for a 60k svc one item listed is "flush brake system".

Is this required or desired?

Why?

Given the complexity of the modern braking systems I would imagine there is a very special machine to do this found usually at the dealer.

Mike =3D=3D=3D=3D=3D=3D=3D =3D=3D=3D=3D=3D=3D=3D

Desired.

Because of the same reasons you change all your other fluids.

the special machine is called a "Foot"...... and so far.......

the dealer hasn't been able to lock that one in.

scribs abell ~uses a "power bleeder"..........a crack head in withdrawal~....

a power bleeder works even better.......

Flush brake system?

Group: alt.trucks.chevy Date: Fri, Oct 17, 2003, 9:02am (CDT+1) From: snipped-for-privacy@REMOVETHISpobox.com (Mike Copeland)

I noticed on another thread where someone was overcharged for a 60k svc one item listed is "flush brake system".

Is this required or desired?

Why?

Given the complexity of the modern braking systems I would imagine there is a very special machine to do this found usually at the dealer.

Mike ======= =======

Desired.

Because of the same reasons you change all your other fluids.

the special machine is called a "Foot"...... and so far.......

the dealer hasn't been able to lock that one in.

scribs abell ~uses a "power bleeder"..........a crack head in withdrawal~....

---------- Actually, to properly flush/bleed GM ABS systems there is a "special tool". Its called a "Tech 1". It is GM's scan tool, and its the only one I've seen that will cycle the ABS. Usually only dealers have it because it is expensive and only works on GM vehicles. Most shops buy a tool that works on all vehicles. I would also bet they dont use it when doing this service, time is money so.............

a power bleeder works even better.......

"Scott M" wrote

Flushing and bleeding mean two different things to me. Flushing is simply changing the brake fluid, and there is no need to have to use a Tech II to perform this. I do brake flushes all the time on many different GM vehicles and they all have ABS brakes. If you start with a system that has no air in it, and you are just going to change the fluid, a vacuum bleeder works quite well.

Now if you need to bleed some air out of the system, most ABS systems still don't "require" the TechII to be able to bleed them. Some of the newer Cadillac and Chevy trucks need to have the ABS brakes bled specifically with the Tech II, but so far, I've only had to do a few of these.

Ian

flushing brakes. What exactly acording to GM are you supossed to do? Aren't you suposed to flush the ABS too?

"Scott M" wrote

Again, we run into terminology problems. GM does have a procedure for brake flushing in their service manuals, but it was intended as a procedure that you would perform in the case of brake fluid contamination by some other type of fluid (say power steering fluid). This procedure involves basically replacing all components in the brake system that would be affected by fluid other then brake fluid.

What we mean by brake flush (ie: the service that the dealership provides for a certain fee) is simply replacing the brake fluid. And it is simple. We use a vacuum bleeder to suck out as much fluid as possible from the master cylinder....(note: this doesn't suck out enough fluid to introduce air into the system)....then we top up the master cylinder and use the vacuum bleeder at each wheel to pull thru the brake fluid until clean fluid is coming out at each wheel. As long as you use your brain and make sure that the fluid level at the master is kept up, you won't introduce any air into the system.

As far as the ABS is concerned, you pull clean fluid right through the ABS section when you perform this procedure. You could do what is referred to as the "automated bleed procedure" with the scan tool, but this wasn't really intended for any flushing purposes, but to purge the ABS unit of possible air bubbles when doing a bleeding procedure. I can't see any reason to do this while simply exchanging the fluid.

Ian

get *all* the old fluid out.....especialy out of the acumulator(s). I think If I was doing it at home I would suck the old fluid out of the master, refill with new, bleed all four wheels, then take it out on a dirt road and work the ABS to death, then bleed again.....But then again, screw it, too much trouble :) Hmmm, The fluid in my Sonoma is getting pretty old, maybe I'll do it this weekend.

You're right. There is some old fluid that remains in the ABS hydraulics as the check valves are closed under normal braking conditions. So long as you bleed out all four lines + calipers/wheel cylinders and have the master filled with fresh fluid, the nominal amount remaining in the ABS hydraulics won't re-contaminate the new fluid. Kinda like changing ATF + filter. You only get 1/3 of the fluid, but so long as the "old" stuff isn't all that bad, this is enough to replenish the additive packages in the exisitng fluids and get the chemical properties where they should be.

My wife's Sonoma SLS needs the brake fluid flushed as we speak. You can probably understand why I've been putting it off lately..............funny how years and years of experience can be erased with one "weird" experience and leave you terrified to touch a farkin' bleeder screw! Feels like the first time all over again, bwaahahahahahahaha.

Doc

"Scott M" wrote

Your method would probably work. If a person tends to be real anal about this sort of stuff, there are all sorts of lengths that one could go to, in order to get every last drop of old fluid out.

Ian

figured you had had enough....:)

Ya, just a thought. I was really wondering exactly what you pay for at a GM dealer for that service, Im sure there is a set price/time for it. Being that it is in the freakin book as a mileage thing one would think there is a "GM procedure" for that good money you give them. I was just wondering as to the amount of time it calls for and what is suposed to be done. That poor guys payed $900 for that stuff after all.

They would want to be sure all the bleeder screws were free and operating correctly before quoting any kind of bleeding job. One would think. B

"Scott M" wrote

It's menu priced at our dealership at 89 dollars, I believe. This includes the brake fluid and .8 hrs to perform the procedure. GM often doesn't have "procedures" for a lot of things in the service manuals. They automatically assume that most of the dealership technicians are fairly well trained in things as simple as regular maintenance. They also require that most techs in any given dealership take some basic training course in brakes....and other things. Note: this is in Canada, from what I've seen and heard over the last couple of years on the internet, the States can be different.

Ian

TY I get it....