brake bleeding techenique

[gsus]

has anybody tried this technique before... how well does it work? does this help you avoid lifting the car & removing the wheels? is it more difficult to do than lifting the car?

also how bad is it if you do not cross bleed your brakes. (ie. do the fronts first then the rear?)

also it was always my idea that you pumped the brakes several times... til the brake pedal felt stiff(er)... hold the pedal down and open the purge/bleeding valve until the brake fluid came out.. then close the valve before releasing the pedal... and repeat until you get a nice stream of brake fluid coming from the valve.... is this incorrect?


taken from another thread (http://3geez.com/showthread.php?p=449392#post449392) on this board:

Ok I have a trick for you that everyone should note in their long term memory...

It's an easy way to get all of the air out of your lines and master cylinder. First you will need someone else to help you and a brake line wrench if you don't already have one for your brake lines.

Alright your going to bleeding your brakes at your master cylinder. Have your friend very slowly press on the brake pedal and then when he's doing it crack open one of the brake lines coming off of the master cylinder and then close it before he reaches the floor with the pedal. Do that with all of the brake lines a couple of times or as much as you wish. Brake fluid shouldn't come out of the lines that you crack open only air. It works awesome and I thought I would share it with you guys. Also for anyone that pumps the brake pedal several times before cracking the bleeder that's a big no no I've learned. In the ASE Newsletter we get at school they said that pumping the brake pedal between bleeding sequences. They said it can damage seals and other stuff.

And if you think you have a leak in your brake booster then I want you to do these two things for me.

Get in the car close the windows turn the radio off and start the car and turn it off and then slowly push down on the brake pedal and it should make a whooosshhh sound. The sound should start slowly as you start pressing on the pedal and when you press more and more the whoosssh intensity should increase.

If it just goes WHOOOSSSSHHH and stays the same and doesn't do like I said before then you have a problem with the air control valve in the booster.

Then I want you to start the car again and turn it off and then pop your hood and then take the check valve off of the brake booster and if the valve is good then the sound should make a pssssss sound. If it doesn't make any sound then your check valve is bad.

-Mike

[Oldblueaccord]

has anybody tried this technique before... how well does it work? does this help you avoid lifting the car & removing the wheels? is it more difficult to do than lifting the car?

also how bad is it if you do not cross bleed your brakes. (ie. do the fronts first then the rear?)

also it was always my idea that you pumped the brakes several times... til the brake pedal felt stiff(er)... hold the pedal down and open the purge/bleeding valve until the brake fluid came out.. then close the valve before releasing the pedal... and repeat until you get a nice stream of brake fluid coming from the valve.... is this incorrect?


taken from another thread (http://3geez.com/showthread.php?p=449392#post449392) on this board:



Well bleeding the master I guess it might work. I buy or there supplied little plastic fittings that screw into the MC port then you run a rubber line back to the master cylinder resevoir and you can pump all the air out.


As far as pumping the brakes to bleed its fine. What you want to watch for is not standing on them to hard or pushing the pedal past its travel. Most newer master cylinders are plastic and yes you can actually run the rod right thru the plastic body. As a rule I start with the wheel farthest away from the MC and work my way around. I dont think you have too remove the wheels on our cars just might be a little easier maybe not.


wp

[Mike's89AccordLX]

Bleeding the master cylinder does work. I've done it 5 different times last semester and my instructor taught me it and he's been doing it for about 35 years.

Another great way to bleed your brakes is a reverse bleed but you need a brake bleeding syringe which costs about $30 :(

And you don't need another person either. You just suck up fluid into the syringe, squirt some fluid out to get the air out. Put the rubber hose from the syringe to the bleeder then crack the bleeder open and start injecting the brake fluid through the lines.

You need to have the master cylinder cap off. And you go around to each wheel. Most of the time you only need to bleed around once. It works really wheel. This also works great on clutches too.

If you don't have a Factory Service manual specifying which wheels you have to goto first, second, third, and fourth.

General Rule of Thumb for FWD vehicles: Start with the farthest wheel away (one of the rear wheels) from the master cylinder, then go bleed the diagonal wheel from there (Front), then bleed the other rear wheel, and last bleed the last front wheel.

That is the best way unless otherwise specified by your auto manufacturer.

For FWD vehicles: Never bleed both rears then do both fronts. Basically all FWD vehicles made since disc brake first were availible, brake systems have been Diagonals.

That means the front right and left rear are part of the the same "circuit" from the master cylinder. And same for the left front and right rear.

-Mike

[Oldblueaccord]

I just meant cracking open the lines prolly not the best way to bleed an MC. Thats the question hes ask and I answered it.


wp

[Mike's89AccordLX]

If you crack the brake lines on the master cylinder you have to do one at a time and you need another person to do this. Brake fluid doesn't actually get out just the air does. And nowadays you don't want to pump the pedal more than once. At school we have a small piece of wood (cut 2x4) that we put under the brake pedal while bleeding so we don't mess up the master cylinder. B/c if you depress the brake pedal further than it should the lip seals in the master cylinder can fail and what oldblueaccord said earlier.

-Mike


If you haven't bleed the master cylinder by cracking the lines at the master cylinder then you can't knock it. I've done it and it works so if you haven't done it then you can't say that it doesn't work b/c you wouldn't know.

[Mike's89AccordLX]

This is the only place that I have been able to find brake bleeding syringes. Auto parts stores don't carry them anymore :(

http://www.bikeparts.com/search_results.asp?ID=CA2000

[gsus]

so bleeding the system throught the master cylinder is just like bleeding the lines at the bleed valves?

pump til siff(or just pump once?)..... hold down the pedal and "crack" (losen???) open one of the lines... then close the line before your friend lets go of the pedal?... and do over again for all other lines

now, how will i know if all the air is out if you say nothing but air comes out through the lines at the master cylinder? also any special tool i should use to do this(i dont want to round anything off)?

[Mike's89AccordLX]

Well you would want to use a line wrench. And that is just for bleeding the master cylinder. You still have to go around to each wheel. Just do the wheels if you aren't replacing your MC then don't bleed it. Unless you bleed the wheels several times and still the pedal is crap. Then do the MC.

You will know the air is coming out b/c air will be pushed out of the fitting. You will know its done when no air comes out.

-Mike

[Oldblueaccord]

I wanna ask why you think there's air in in the Master Cylinder? Usually that only happens when you have replaced it. If you did its easier to bleed it on a bench with those plastic fittings/hose that come with them now days. Just changing out brake pads should EDIT NOT get air into the MC.


wp

[Mike's89AccordLX]

Ok seriously how many posts do I have to say this? If you haven't done it then stop saying its not the best way to do it. #1 its easier and #2 its alot faster. There can be air in your master cylider many ways. #1 replacing it #2 someone let the brake fluid get too low and now there's air in it. etc.........

And I hope to god you just don't change brake pads. If so, I just retract any statements showing you knew anything....


Point being I have 1.5 years experience doing this type of stuff and my 2 instructors (both ASE Certified Master Mechanics) have over 50 years experience between the two of them.

I trust them more than many people on here.

[gsus]

thanx alot mike... my pedal is so crapped out that im just going to try to bleed the entire system
gsus