It won't do any harm, certainly. But don't kid yourself into thinking that there is a hung jury either.

 

with cclive!!

Brake fluid is hygroscopic - it absorbs water. That's why you should flush your brake system every 2 years or so.

The fluid is designed to absorb water to try to keep down corrosion and deterioration of seals throughout the system.

I flush before and after track events to get old fluid out of the entire system as completely as possible and replace it with fresh high-boiling point fluid with no water in it. I want to get any old fluid that may have absorbed the least bit of water out of the system so that when I'm doing multiple high speed stops I don't boil the water out and have the compressible gas give me a soft or no pedal - not fun when going into a corner from high speed!!

Guess where the HOTTEST portion of the entire brake system is when doing a hard stop - street or track. It's the CALIPERS!!!

You've got little nooks and crannies as the fluid galleys in the calipers bend around from the brake hose connection to the pistons, and that's where the old fluid that has absorbed water or is just plain tired is sitting and must be replaced.

The turkey baster method just is not going to get fresh fluid down to where you need it the most - the lines and hoses farthest from the master cylinder, and especially inside the caliper.

You've got to bleed the brakes by opening the bleed valves and letting the new fluid push the old completely out of the system - flush until the fluid coming out of the bleed valves is clean and clear new fluid. That's the only way that a system flush will get new fluid out to where it's needed the most - the end of the lines and the calipers.

Bob

 

There was another thread on the same subject a time back and the yes votes carried that one.

 

While it probably won't do any great harm, many manufactures tell you not to mix different brands of brake fluid, even if they are both DOT 3. While they are supposed to be compatible, I have read warnings about mixing brands in a few places, and I think it may be due to the differences in the various additives that different brands use. So it probably wouldn't be advisable to add a different brand to the master cylinder than what was already in the system. This is another reason why it's better to simply do a complete flush. Also, the fluid that gets exposed to the most heat is what is in caliper, and that is what really needs to be changed out. I don't believe just replacing what is in the master cylinder is going to offer much, if any, benefit. You really need to do it right and bleed/flush the whole system.

And since brake fluid is hygroscopic and absorbs water, the water laden fluid will migrate to the lowest point on the vehicle, which will be the calipers. The boiling point of brake fluid goes down dramatically as it absorbs water, and this can cause your pedal to go completely soft when the caliper gets overheated and the fluid in it boils. You really need to get that old fluid out of the calipers, since that is where the real work of the brake system happens.

 

to do a complete brake flush involve removing the tires?

 

Removing the wheels, yes.

 

Is it possible just to use a machine and drain it from the master cylinder without having to remove wheels?

 

You'll have to remove the wheels. Even with the early C6 wheels with the wide spokes, you just can't get through the spokes and past the rotor to get your tube and wrench onto the bleed valve, which is kind of on the backside of the caliper.

If you've got a Z06 or BBK with a fixed caliper, there are 2 bleed valves on each caliper, one of which is on the backside of the caliper.

So.....you'll need to jack up the car and remove the wheels.

Bob

 

So if someone just hooks up that pump machine to the master cylinder to suck out the old fluid that wouldn't be a total brake flush? Sort of like just letting the radiator drain and add new fluid without flushing out all of the existing old fluid?

 

I don't know of any machine that sucks "ALL" the fluid out of the entire brake system through the master cylinder. If there were, you'd still need to open the bleed valves to allow air in on the other end. Then you'd have air in all the lines, and when you put new fluid in the m/c you'd need to open the bleed valves and apply pressure to the new fluid in the m/c to push it all throughout all the lines and out through the bleed valves in the calipers to get the new fluid into all parts of the system.


That's kinda what this whole thread is about - the "turkey baster method" involves sucking the old fluid out of the m/c and then filling it with new fluid. That just isn't going to get new fluid all throughout the system.

There are several ways to bleed the brakes, but they all involve opening the bleed valves at the calipers and applying pressure (or suction) to get the new fluid you put into the m/c to flow all through the system and out of the bleed valves. Thats the ONLY way to get new fluid into all the lines and down to and into the calipers:

• The old traditional method involves opening the bleed valve and then pushing down the brake pedal, which will push fluid out of the open bleed valve. Close the bleed valve before releasing the brake pedal. This method requires a helper to push the brake pedal while you open/close the bleed valve - unless you have speed bleeders.
  
  
• Some people say they can just open all the bleed valves and do a "gravity bleed". They open the valves and just let the fluid drain out. I haven't had any luck with that method. You have to keep checking the m/c and refilling it with new fluid as the old drains out. You DO NOT WANT TO RUN THE M/C DRY and allow air into the system with any method you are using!!!
  
  
• There is a mityvac unit that will pull/suck fluid out of the bleed valve so you don't need to push the brake pedal:
  
  
  
  
  
• I use a Motive Power Bleeder. This provides pressure to the brake system through the m/c so you don't need a helper pushing on the brake pedal. The pressure still just pushes the fluid out of an open bleed valve:
  
  

So.....to my knowledge there is nothing that will completely suck all the fluid out of the system through the master cylinder. If there were, you'd still need to open the bleed valves to allow the fluid to be sucked out of the calipers and lines throughout the system.

Bottom line - if you want to do a proper bleed/flush of the brake system to get new fluid throughout the entire system, you're going to need to jack up the car, take off the wheels, and open each bleed valve while applying pressure to the system to move the new fluid from the master cylinder all throughout all the lines and down through the calipers and out of the bleed valves.

Bob

 

Is this how the dealership does it?
A shop did my car using a device like the above in this pic except it was a metal container.
Is there a way to tell if they bled the brakes without seeing them remove all 4 tires?
I'm starting to suspect perhaps they may not have done the second part removing the wheels as this probably takes alot more time.
How many bottles of brake fluid do you need to do a complete brake flush evacuating all the old brake fluid out and replace with new synthetic brake fluid?

 

Not bleeding the complete system won't give near the benefit of a complete bleed, however if you pull all the old fluid out of the master cylinder and put new fluid in it will definitely help. You have removed moisture laden fluid and replaced it with moisture free fluid. Just remember to have the fluid bottle and the MC open as SHORT a time as possible. The fluid absorbs immediately upon contact with the atmosphere. Also the system will mix the new and old, and do it quite well when the traction control or abs is activated. I check moisture content and doing this once a year has worked quite well on a number of vehicles I own.

 

They may very well have a high tech version of the Motive Power Bleeder. The real high-tech ones have a diaphragm to separate the pressurized air from the fluid so air (which has moisture in it) won't get pushed into the fluid.

If you have a lift, you could probably get to the bleed valves on the floating calipers on a regular C6 by reaching in behind the wheel so possibly you wouldn't need to remove the wheels - I've never tried it that way. If you're working on a car with fixed calipers (Z06, GS, a car with a BBK upgrade to Brembo, StopTech, or such) that have 2 bleed valves per caliper, you'll need to remove the wheels.

When I do a full system flush I use Motul RBF 600 which comes in 500 ml bottles. It usually takes me 1-1/2 bottles (750 ml, a little less than a quart) to get nice clean/new fluid coming out of all the bleed valves.

You don't "evacuate all the old fluid out". What you're really doing is putting new fluid into the m/c, opening the bleed valves, and applying pressure (brake pedal, power bleeder) or vacuum (MightyVac) to have the new fluid push down through all the lines, through the calipers, and out the bleed valves. This movement of new fresh fluid through the system pushes the old dirty moisture laden stuff out.

It's not like draining a coolant system and then refilling it. You don't ever want to empty out the brake system and get air in there. You want to keep fluid in the lines at all times so no air gets introduced into the system. That's why when you're bleeding you need to check the m/c frequently and refill it so no air gets in the system.

In a coolant system you have a water pump that circulates the coolant all throughout the system. You can completely drain all water/coolant out, put in new, run the car for a few minutes which will circulate coolant through the radiator and allow any air in the system to be pushed out as the fluid circulates through the coolant tank, then you can simply top off the coolant reservoir to the proper level.

You can't do that with the brake system. It's a closed system with no circulation going on (well....mostly no circulation - there is a pump in the BPMV to operate the ABS feature, and some limited amount of fluid will circulate a bit when the ABS valves are cycled during ABS activation).

So.....your dealer may well have used a power bleeder device, and they may well have been able to reach the bleed valves if the car was on a lift where they reach in from the rear of each wheel, and probably around a quart of new fluid or so should push all the old fluid out.

Bob

 

Keeping clean fluid in the reservoir cannot hurt, and it might make the master cylinder last longer.
I have bled my brakes, but I also put clean fluid in the reservoir whenever I refresh the clutch fluid. It just takes one small bottle of brake fluid.

 

Just one bottle of brake fluid to flush the whole brake system?

 

I can't be sure if the shop that did it bleed brakes without seeing them do it. but they did have car up on rack and used a pump on the master cyclinder.
I wish there was a way to tell if the system was bleed.

checked receipt and it says brakes were bleed So I will go by this.

 

Here is a cheap and effective tool I like to use for bleeding brakes. It is a one way valve that you connect to the bleeder, and then you just pump the brakes. It will only allow the fluid to flow in one direction, so air won't be sucked back in.

The best part is it only costs $20.

http://www.motionpro.com/motorcycle/...brake_bleeder/

 

I'm about done with this thread. I think that everybody can tell that I think that just sucking old fluid out of the m/c and putting a few ounces of new fluid in is not going to effectively do what you need to do every couple years to get the old fluid that has absorbed moisture out of the system, out of the nooks and crannies, and out of the calipers.

Butt.....let me just throw out some other info for those that do want to bleed the brakes properly.

The master cylinder has a baffle in it. To those of you that are sucking out fluid and putting in new, do you have a tube to snake up into the front section of the m/c to get the fluid out of that chamber???

The old traditional method of bleeding brakes has that you start at the caliper farthest away from the m/c and work up to the closest one last - that would generally be RR, LR, RF, then LF.

However, our Service Manual says that when you bleed the brakes you should bleed in the order RR/LF, then LR/RF.

The 2 chambers in the m/c are for those 2 diagonal circuits. The purpose is so that if a line breaks and you lose fluid, say from the RR caliper, then the you'll lose the RR/LF brake. Hopefully the other chamber on the other side of the baffle in the m/c will still have fluid so you can get braking from the other diagonal circuit - the LR/RF in this case.

The Service Manual also discusses using a Tech 2 to open the ABS valves in the EBCM so you can flush those ABS circuits.

So - even though I think it's essentially a waste of time, money, fluid, and effort - if you are going to suck old fluid out of the m/c and replace it with new, make sure you have a syringe, baster, or whatever you use to suck out old fluid, that will allow you to get up into that front chamber of the m/c. Filling it isn't a problem - when you put in new fluid and it gets to the level of the baffle, it will just flow over and fill up both chambers.

Bob

 

Hey Bob, I put almost a large 32 once bottle in mine over time...I used a 1/8" dia air line attached to my syringe to reach as deep into both chambers as possible....

I would get about 6 ounces out at a time.


thanks for the info.

 

I just tried the turkey baster method and eventhough I made sure I only removed about half of the fluid from the master cylinder and refilled, I now have the check brake fluid and service active handling system messages on the DIC