Proper brake bleeding procedure

I began with the passenger rear wheel, followed by the drivers rear, passenger front, and driver front. Are there any other bleeding locations? I've read that proportioning valves can still have air trapped in them. I'm getting no air out of my bleeder valves on the calipers, but my pedal still feels a little mushy. Any insight?

To properly bleed the system you should bleed the Right Rear then the Left Front. (That is one half of the system) Then the other half, The Left Rear and Right Front.

The two systems, if you will, are cross ways.

Did you start bleeding by doing a gravity bleed first. That is, open the bleeders and remove the top of the Reservoir to allow gravity to bleed the fluid and air out of the system.

Then, when doing the 2 person bleeding by applying the brake pedal you should follow the above mentioned sequence.

Some people have had trouble getting all the air out due to the ABS module trapping air and it can take some time. I have had good luck with gravity bleeding taking 90% or more of the air out and the remainder under foot pressure.

If still having problems you may need to buy a vacuum bleeder from the auto parts store or Sears for about $20.00 to $30.00 and vacuum bleed each caliper by hand pump.

I have yet to need my pressure or vacuum bleeder on the Riv and I have bleed the brakes after the system has been cut open and drained at least 3 times since I've owned it.
I just bleed it as I've mentioned and it's done.

manofmany wrote:

I began with the passenger rear wheel, followed by the drivers rear, passenger front, and driver front. Are there any other bleeding locations? I've read that proportioning valves can still have air trapped in them. I'm getting no air out of my bleeder valves on the calipers, but my pedal still feels a little mushy. Any insight?

this is why I built myself a power bleeder using a garden aprayer. The write up is on this site.

Albertj

My brake pedal is still mushy after replacing the MC and all 4 calipers and bleeding system.

Is there a special way to bleed for ABS? My ABS has been out for a long time and I don't really miss it so didn't do anything about it. But now I have this braking problem.

Could there be some sort of vacuum loss with my system? I'm confused right now.

no fluid loss either.

You might have trapped air, or you might have an MC with worn seals (can be rebuilt but typically replaced). Hard to tell which from here. If power bleeding system does not work you can try replacement.. also watch for one or more failed wheel cylinderslook for fluid behind the boots. What do you thi k you want to do?

Fluid level is steady. MC was just replaced with a reman. Is it possible the reman is crap too?

I bled as I always have done before. No air in the tubes. Did 100 strokes per wheel.

Is there anything different about bleeding an ABS system? As stated, I bled it the same way (right left/right left) as I've done in the past with no problems.

ABS has been out for some time. Never had a problem like this or with the bleeding though.

Pedal still spongy and does not give a firm stop. Brake booster problem? Vacuum?

How did you bleed the MC?

Technically to bleed the ABS you need a Tech-II to actuate individual ABS pistons. I've ben lucky and never had to do this.

Why did you replace all 4 calipers? That's unusual. Maybe you have a collapsed brake hose somewhere?

As long as you didn't bleed the system dry, the ABS pump should be all right.

Spongy means there's still some air in there somewhere.

My ABS system is not functioning and hasn't for years.

After snooping around the net my options sounds like:

1. Old brake hoses ballooning under pressure
2. Air still in system
3. Defective new master cylinder


Option 2 seems strange because the brakes were spongy before I replaced the MC and calipers. I pumped 100 times each wheel and so no bubbles. Something is weird here. Even forums I've looked at on the net with this issue seem all unresolved.

I wonder if a malfunctioned ABS pump could still trap enough air to cause your issue?

Not saying the old pedal bleed method doesn't work, but I don't do it on the Riviera. A slow gravity bleed is free and almost guaranteed to get the air out of the lines (but not the ABS pump if that's the case). I prefer to use a Mighty Vac pump to bleed the lines. After doing it that way, I wouldn't try anything else. Can't guarantee it will remove air from the ABS pump, if there is any.

In my experience, there is a different feeling between air in the lines and the hose ballooning. Soft hoses feel "mushy" but eventually firm up and provide adequate pedal feel. Air feels more like "springy" and probably won't provide enough pressure to safely operate the car. Soft hoses can be visually inspected when the pedal is depressed. Ballooning can be clearly seen.

Don't see how a defective MC would cause a spongy feel, but guess it's possible. IMO a bad MC would cause the pedal to slowly fall to the floor under pressure, with multiple pumps required to firm up the pedal.

Thanks Aaron.

So here's the sequence of events that led to this problem. I think I'm arriving at a possible solution...

1. Heard right rear wheel grinding, inspected pads which were worn thin and digging into rotor. Replaced only pads even though rotor was marred. Planned to replace rotors the next week.

2. Couple days later started noticing pedal slowly falling to floor under pressure. Can pump brake to bring it to a decent firmness.

3. Suspected MC but bought new rear calipers and rotors to be sure.

4. The following week I installed new MC, rotors and new rear calipers. Also replaced brake fluid and did a thorough bleed (100 pumps per side).

5. Closed up system and still have mushy brake pedal. Which doesn't feel as bad as it did before I installed all the new equipment but feeling is still there. I can get it to go to the floor still if I put enough pressure on it. It will not come to a hard stop but I can still stop the vehicle. Just takes a little more of a stroke with the pedal.

I feel like the last thing to check would be the flex hoses, especially in the back since if you go back and look at 1. this is where all of this began, with replacing the rear pads only. With the new pads I may have put so much pressure on the old flex hoses that they started to balloon or developed a small pin like hole. My fluid level has been consistent all along but a pin hole may make fluid level observation unnoticeable. I have had a front hose fail on me a few years ago and actually obstructed fluid to the cylinder (car pulled to one side). Am not noticing that here.

Anyone with flex hose ballooning or pin hole leak experience?

Ive had hoses fail on two different occasions with two different GM cars. They were both front disk brake hoses, one a rubber OEM hose, the other a braided stainless ZZP hose on the Riv. When the rubber hose failed, it ruptured all at once, the pedal went to the floor, and it was very difficult to slow the car. When the steel hose went, it leaked a pinhole stream that caused the pedal to slowly fall to the floor under braking. Pumping the pedal I could easily build pressure. It felt exactly like a failing master cylinder.

If you had a pinhole, there would be plenty of fluid evidence around the trouble area. Fluid in the line is pressurized to around 800-1000 PSI under braking. When it finds a hole, even a small one, it will find a way through that hole, and plenty comes out. Also it would quickly become larger, so if you had a hose leak, it should be obvious.

AA is right - if the pedal sinks to the floor while holding it down, you have either a) a fluid leak or b) a bad MC.

How did you bleed the MC?

Checked the fluid this evening. Still constant. It doesn't really "sink" to the floor anymore. It's just a longer stroke with no "hard" stopping power. Feels mushy too. I can depress the pedal pretty far down but no real firmness. It's hard to bring the car to an abrupt halt.

I bled the MC using the included bench bleed kit. Two tubes from each port routed back to the reservoir. It had pictures of an old style MC where you can route each tube into the respective reservoir but since I didn't have that, I routed both into the cap. Hopefully that doesn't make a difference. Each tube was submerged and I pumped until no air was left in the lines.

Now, I've noticed an interesting noise today. At a stop when I press really hard to the floor and then let go with my foot, I hear a metallic click coming from the initial problem wheel (rear right). What could this be? I haven't had a chance to get under it because no one has been home to press the brake while I check out the sound.

Sounds like the caliper and bracket bolts should be checked.

OK so im gonna bleed tomorrow. soo...
Rear Right
Rear Left
Front Right
Front left???
and any other bleeding tips for a nice firm pedal???

A mighty vac pump makes the job easier and faster, and is a good idea for ABS-equipped cars.

MrWood88 wrote:

OK so im gonna bleed tomorrow. soo...
Rear Right
Rear Left
Front Right
Front left???
and any other bleeding tips for a nice firm pedal???

did you actually read the earlier posts?

if not, why not - then repost with questions. Point is, you will learn about pressure vs vacuum bleeding, general instructions if you are just new at it, etc.

albertj wrote:

MrWood88 wrote:

OK so im gonna bleed tomorrow. soo...
Rear Right
Rear Left
Front Right
Front left???
and any other bleeding tips for a nice firm pedal???

did you actually read the earlier posts?

if not, why not - then repost with questions. Point is, you will learn about pressure vs vacuum bleeding, general instructions if you are just new at it, etc.

i read it and got some info out of it but it seems his problem was never resolved so i was just asking further.
i just recently replaced my whole rear right caliper and semi bled the system just to get fluid to the caliper
when i got in the car i started it up because i had to move it and the pedal was mushy and went practically to the floor.
so im hoping tomorrow when i bleed the whole system it will get better.

MrWood88 wrote:

albertj wrote:

MrWood88 wrote:

OK so im gonna bleed tomorrow. soo...
Rear Right
Rear Left
Front Right
Front left???
and any other bleeding tips for a nice firm pedal???

did you actually read the earlier posts?

if not, why not - then repost with questions. Point is, you will learn about pressure vs vacuum bleeding, general instructions if you are just new at it, etc.

i read it and got some info out of it but it seems his problem was never resolved so i was just asking further.
i just recently replaced my whole rear right caliper and semi bled the system just to get fluid to the caliper
when i got in the car i started it up because i had to move it and the pedal was mushy and went practically to the floor.
so im hoping tomorrow when i bleed the whole system it will get better.

Now *this* explanation you just gave helps me better understand how to help. And I apologize I think you said as much, before, in another post. Maybe the following will help:

My guess is that when you "Semi-bled" the system you still had air trapped in it. Brake fluid is pretty thin and brake lines are pretty narrow. What looks like a little bit of fluid that drips out during a caliper change can actually represent fluid that was in several feet of brake line. When you have a line that is open for a while and then you pump to bleed the brakes the fluid has to move both ways in the lines. Since it moves both ways (toward and away from the master cylinder) you can introduce an air pocket where you did not necessarily have one. This is one reason why power bleeding or vacuum bleeding is preferable to pumping the brakes -- the fluid only moves one way, and so although you *can* introduce an air bubble in the lines from power or vacuum bleeding it pretty much only happens if you ignore the proper order to bleed (bleed the longest line first then the next shortest in order). This is also the reason that Robotennis recommended pinching the brake line shut with a pair of vise grips - I don't like that in part because of possible damage and in part because the timing of a caliper replacement usually more or less coincides with when you ought to change the brake fluid anyway... so I would not do it, I would just use a power or vacuum bleeder to bleed all the lines. Robotennis already pointed out there are ways to pinch a line shut that don't necessarily cause problems in his experience. And since it is your car you get to choose which approach to take...

Anyway - if an air pocket got int the ABS distribution block or even all the way back up to the master cylinder, there is no telling where it ended up and you then have to bleed all the brake lines. In order to prevent the possibility of air in the lines you have to bleed the most lengthy line first as measured from the MC - that would be right-rear.

Another possibility - sometimes the master cylinder (MC) internal bore will corrode in places where the piston does not normally move. Then when you pump the brakes to bleed them, you move the piston past the corrosion, which cuts the o-ring on the piston. After that you get a soft brake pedal because fluid is escaping past the piston. If that happens you need to repair or replace the MC. In practice, professional mechanics replace the MC to save time and car owners doing their own repairs replace the MC because they can not rebuild them. Usually the primary impediment is there is a retainer bolt in the MC that is held in place with "loctite" and is nearly impossible to remove, and the secondary impediment is that honing the MC cylinder, although not difficult, is an art requiring practice that the car owner may not have had the opportunity to get even if they have the equipment to do it.

I think the bottom line for you is you need assurance that completely bleeding the system will fix things. What I am telling you is definitely try that but don't be surprised too much if it does not. There may be a different reason for the "soft pedal" including that the partial bleeding that you did may possibly have caused a problem.

Albertj

Soo....
Ive chose to have someone bleed and flush my brakes i have done it in the past on other cars
but after reading all the posts and answers it didnt assure me.
There seems to be no SOP(standard operating procedure) and 3 or 4 different "ways" of doing it and each person says theres is the best way.
It seems like a better deal to pay someone 40$ to do this then spending the moneyy on some vacuum pump and fluid and doing it yourself, which ive already spent close to that on a pump and fluid.
If we can have a topic where we standardize to some degree this process would be ideal....

EDIT: SO today i took the riv to a shop today for a flush and bleeding and......
The pedal feels awesome its right there at the top and stops on a dime!! (a big dime but still great! lol)