Bleeding Brakes

[JasonA]

When I get my new pads, I'd like to bleed or flush the entire braking system. I don't know if it's ever been done, which means it probably hasn't. I've seen some references here from folks who have done their own. There are a few references in the manual about doing it, and even about letting the ABS module flush it for you?

Can you all describe how you've bled the brakes on your Cadillacs? Also please let me know what parts I'll need. I've seen bleed kits, one-man bleed kits, etc. I've never done a brake bleed before, and I'd like some tips from you all, the experienced, so I don't screw something up!

Also, I assume I need to fill it up with DOT3 or 4 fluid? I've seen DOT 5 on the shelves, but I recall from Bobynski and others that the existing brake lines are validated for DOT3 or 4 only, and newer types may cause damage to the system? Is that accurate?

Thanks in advance!

[growe3]

Some brake fluid comentary at the link below. About 3/4 of the way down the page is some important information about DOT 3,4,& 5 brake fluids.

http://www.csaa.com/global/articledetail/0...57C2026,00.html

-George

[shiden_kai]

When I get my new pads, I'd like to bleed or flush the entire braking system.  I don't know if it's ever been done, which means it probably hasn't.  I've seen some references here from folks who have done their own.  There are a few references in the manual about doing it, and even about letting the ABS module flush it for you?

Can you all describe how you've bled the brakes on your Cadillacs?  Also please let me know what parts I'll need.  I've seen bleed kits, one-man bleed kits, etc.  I've never done a brake bleed before, and I'd like some tips from you all, the experienced, so I don't screw something up! 

Also, I assume I need to fill it up with DOT3 or 4 fluid?  I've seen DOT 5 on the shelves, but I recall from Bobynski and others that the existing brake lines are validated for DOT3 or 4 only, and newer types may cause damage to the system?  Is that accurate?

Thanks in advance!

I use a vacuum bleeder to flush the brake fluid out on all the vehicles that I work on. If you are simply exchanging the fluid, there is no need for any complicated procedures. In your case, if you have a lot of time on your hands, then just let gravity do the work for you. Put the car up on stands, replace your pads, pump the brakes up to get the pads out to the discs, then just open a bleeder screw and let the fluid drain while keeping an eye on the level in the master cylinder.

If you happen to have a helper, throw them in the front seat and follow this

procedure. Open a bleeder screw, have the helper slowly push the pedal to

the floor and hold it there, close the bleeder screw, have them release the pedal, repeat until the fluid runs clear.

Oh yeah, everything will go much quicker if you first suck out as much of the old brake fluid out of the master cylinder as you can, then top it up with new fluid. This give you a lot less "old" fluid in the master cylinder that has to pass through the entire system.

Ian

[JohnnyG]

I probably did mine all wrong, but it's working fine. No lights bells or whistles, and no codes. You would need special equipment to use the antilock brake pump to flush the system, like something only available at a dealer.

I did mine the old fashioned way, with the wife pumping the brakes. Started by siphoning out the fluid in the master cylinder. Don't try to get it all out, you don't want air to get into the system from there. Filled it up with DOT 3-4 fluid, and did it again. I started with the fronts, because thats where I was changing the pads. After that was all done and the new front pads installed, I went to the rear brakes and bled them out. It helps when using this method, to get a piece of 1/4" clear plastic tubing to slip over the bleeder valve. This tubing is inserted into a jar (about 1 quart size, a 2 liter bottle would be OK too), with a little bit of clean fluid in the bottom. This acts as a receptical for the drained fluid and prevents air from being sucked back in the system should an error in timing (the wife) occur. My bleeder valve was a 10mm, you only need to open it a 1/4 turn to let the dirty fluid be forced into the bottle. 1 quart was enough for me to do the whole job.

[Ed Fenwick]

Aloh,

I have always herd that pumping the brakes will push the piston out too far. ie past where it normaly goes and may score the rubber seals 'am told that it is best to use a suction pump (hand pump) to draw the fluid out. Start at the wheel nearest to the fluid resovior and work your way to the farthest . Draw out the old fluid unitl you see clean fluid and no bubbles. Don't let the resoviour run dry or you will get too much experiance bleeding the system. Easy job to do!

Enjoy it Ed

[JasonA]

So when you guys are saying to suck the old fluid out, you're talking about connecting a hose to the bleeder screw, submerging the hose into a bottle of new fluid, opening the bleeder screw, and then "sucking" the new fluid up and to the master cylinder? In this case, I'd imagine that once I sucked 1/8 quart through at each wheel, maybe 1/4 quart for each rear wheel, that'd be plenty of assurance that I got all new fluid in the lines?

Does anyone have a good liquid pump they recommend for this purpose? I've purchased a few, but they've all been flaky and I could never get one that really worked right.

[CaddyShack24]

I think they mean to suck most of the fluid out of the master cylinder and refill with new brake fluid.. that way when you bleed the brakes, you'll pull out the old fluid and then some of the new fluid. like flushing the toilet.

The submerged hose thing would keep air from being sucked back into the system.

When you press the brakes, the fluid is compressed and squeezes the caliper..

When you release the brakes, the pressure is released and can pull in air (since you have an open bleeding screw) keeping it semerged would pull back in fluid.

For a pump, ya could use a turkey baster or anything with suction to it..

Only other thing i can recommened doing is inspecting everything in the wheel well and maybe cleaning the rims / tires

Oh, Shidan was talking about using a motorized vaccum to pull it threw

[Ranger]

So when you guys are saying to suck the old fluid out, you're talking about connecting a hose to the bleeder screw, submerging the hose into a bottle of new fluid, opening the bleeder screw, and then "sucking" the new fluid up and to the master cylinder? In this case, I'd imagine that once I sucked 1/8 quart through at each wheel, maybe 1/4 quart for each rear wheel, that'd be plenty of assurance that I got all new fluid in the lines?

Does anyone have a good liquid pump they recommend for this purpose? I've purchased a few, but they've all been flaky and I could never get one that really worked right.

No, just the oposite. Open the bleeder valve and suck the brake fluid FROM the master cylinder reservoir down thru the bleed valve. I think the system holds about a quart.

[JIMDTS]

Just take an old turkey baster and suck the fluid out of the master cyl. then refill the master cyl with clean fluid then bleed the brakes that way you don't drag all the old fliud through the system which would take longer to bleed the system to get to the new clean fluid..I use the turkey babster and a old coffee can to just squirt it into it's pretty quick to do. Just make sure you don't drip brake fluid on the paint it sure eats the paint it works like paint remover..if not better..I sometimes throw a cover over the front fender so I don't drip the brake fluid on paint work

Good Luck

Jim

[JohnnyG]

Wait a minute, wait a minute. Ed, that can't happen unless the calipers are removed from the discs first, something you do NOT want to do. How can pumping the brakes move the pistons past where they touch the rotors if the rotors are still in place?

Anyway, I siphoned the fluid out of the master cylinder, and refilled it, TWICE before starting the job. "Siphoned", stuck a long peice of clear tubing into the reservoir, used my mouth to get the fluid moving into the tubing until it started flowing down toward the ground, where the receptical was....an old coffee can. Hey don't laugh, it cost me $53.00 for a $600.00 brake job.

Using the same tubing, but attaching it to the bleeder valves on each wheel cylinder, you have two choices. I actually never thought of letting gravity do the work, but just letting the fluid trickle into a clear plastic container from the (opened) bleeder valves, might work, a little slow, but might work. Just remember to keep the master cylinder full at ALL times, less you get air into the system.....bad.

Second choice, and the ONLY one I use, is called the "Wife" system. The wife, or someone else you like VERY much, helps by pushing the brake pedal down for you while you open and close the bleeder valves, one wheel at a time, thereby forcing the fluid out. This system is NOT for professonals, it is STRICTLY the stuff that shadetree mechanics are made of. Further, you MUST like them very much for two reasons (1) You wouldn't trust this job to someone that hates you. and (2) If they DO screw it up, you won't hate them forever.

P.S. JIMDTS is correct, the turkey baster will work fine for the master cylinder, but that's where the similarities end.

PPS Larry is also right. Once the fluid in the master cyl. is clean, the rest of the fluid goes DOWNWARD toward each wheel in succession, until all 4 are done and clear fresh new fluid is seen being forced out through the clear plastic tubing. Keep in mind that through this ENTIRE process, NO AIR can be allowed to enter the system at ANY point.

[JasonA]

Thanks guys for all your replies. I think I got it. This is basically what most "instructions" say, but they usually leave out lots of details. You guys don't. Again, many thanks.