Brake bleeding help after master cylinder

[storlied]

So where do I go from here? I replaced it with a used unit that was full. So I know there's air in the lines that connect to it.. what now?

 

[deweyville65]

It is my understanding that you will need someone with a special tool to bleed the ABS controller. I have never had to replace the master cylinder (yet). I have always been able to bleed the brakes with my Mity Vac. It is a one man job that way.

 

[Fastest Caskets]

I always just have someone punp the brakes inside the car. When the pedal is hard have your assistant hold the pedal to the floor and crack one line on the master.
You should see hear air coming out. with pedal still fully depressed, retighten line and repeat untill no more air is heard,seen. repeat process for the other line on the master.

I think there is a special procedure for the abs controller, but I've never really had to deal with that after a measter cylender install. Hope this helps, good luck

 

[storlied]

This is what I'm running into... I don't believe there's any air in anywhere except the ends of the lines that go into the master... along with maybe little bits of the ports for the master.... so... which port do I disconnect to cycle the fluid through?

 

[CDW6212R]

You should attempt to bleed the brakes with a vacuum pump, hoping that the air will bypass the ABS module. Don't start it and hit the brakes with air upstream of the ABS pump, that is very likely to force the air into the pump.

I'd try vacuum first, not pumping, and gently, hopefully the air can be pulled through the bypass section of the ABS without entering the pump itself. Normal flow/pressure bypasses the ABS pump, but it doesn't take much extra pressure to push some flow through the pump.

If any air gets into the pump, the brakes will feel more soft, spongy, or take more travel to work etc. Once that happens, only a special ABS diagnostic tool can be used to force the ABS module to function(pump), while bleeding the brakes.

 

[storlied]

Can you run me through this? What it seems is the only places there will be air is the very ends of the lines going into the master... the master itself is full, there might have been a few drips from the holes... uhh.. so which line do I disconnect to get the air out? I don't have any kind of vaccume or anything??

 

[CDW6212R]

You already most likely installed the MC properly, now you have to bleed the brakes to get any remaining air out of the system. It's not possible to R&R components of the brake hydraulic system and not have any air get in the lines. Assume that there is always something to bleed out of them.

Think of the ABS pump as an interstate truck stop. Almost 100% of the traffic flow never goes through the truck stop. With ABS the pump may not ever have any fluid go through it except for when the ABS module makes the pump function. So ideally it would seem that you could bleed an ABS vehicle and have all the air in the lines be forced around the pump and not through it. But don't assume that no air will get in the pump, and bleed it in any way you like. I'm sure that you have heard of how much trouble it is to get air out of an ABS pump, so do as you are and try to do what you can to avoid that.

You have to bleed the brakes to get any air to come out the caliper bleed screws. There is a bypass to the ABS pump, that's how you want the air to get past it. I'm suggesting to avoid a bleeding method that could make some of that air go into/through the pump. I think applying a vacuum at the bleed screws is more likely to get the air to bypass the pump, than the normal bleed methods.

I have both a vacuum pump bleeder and a pressure bleeder. I love the pressure bleeder, which I bought more recently. I plan to never use the vacuum pump if I can use the pressure bleeder(requires an adapter for the MC top cap opening), but for ABS use when a MC is replaced, I'd use the vacuum bleeder first.

 

[sexy_mama_k]

What can I do if I can't apply any vacuum anywhere? I find it a bit annoying I might have to bleed the brakes completely.. from where that air is... it seems like it could be avoided somehow without dragging that air through Everything.

[lol, didn't realize I was on her account] Anyways, this is Storlied

 

[CDW6212R]

There isn't any other outlet for air, which is why you try plug any ends that are opened, and bench bleed the MC.

It doesn't take long at all to bleed brakes, but any special process like the ABS bleeding is a whole different story.

Try the parts stores, see if any of them rent vacuum bleeder kits. They have surprised me about some tools that they carry.

 

[sexy_mama_k]

I'm curious, you mentioned there's a bypass built into the module, so the brakes can act as they normally will when the ABS isn't active... but there's still the possibility of getting air in... uh, would it make a difference if I hit my ABS kill switch at all when doing a normal brake bleed? I have a feeling I Should be fine bleeding the brakes the proper way, and to hit the killswitch it would ensure the ABS pump doesn't do ANYTHING at all [not that I'm saying it would anyways but you never know]

Tomorrow I plan on bleeding the brakes the normal way, LR, RR, RF, LF.. ect.. or whatever.. I've been doing some reading and it seems like it's a 50/50 split on the possibility of getting air into the actual pump? Whats your thoughts on this with our specific application in mind?

I need to get this damn thing on the road asap.. bleh

 

[sexy_mama_k]

[Delete] Double Post

 

[CDW6212R]

Normally the ABS pump doesn't do anything, you can feel when it works under very hard braking.

That bypass of the fluid is normal when driving. Of course fluid is forced through the pump when it's operating. I am not sure however, that fluid under pressure by the pedal cannot get into the pump, just that the least resistance goes around the pump.

Bleeding the typical ABS systems since the 80's is still normal for all but certain unique ABS systems(Teves for example), but there are lots of people reporting soft pedals after bleeding. I have not researched any of those to find out what parts were changed(MC, lines, ABS pump, caliper), or what method they used for bleeding. Some of them are like your example, and normal bleeding ended up with some air in the ABS pump.

Without spending countless hours researching to find out what percentage of those were bled by hard pumping, gentle pumping, vacuum pump, pressure pump etc, its safe to say that normal bleeding has a risk of getting air into the pump.

I simply posted in the beginning that I think a vacuum pump would have the least chance of ending up with air in the pump.

I won a 1995 Crown Vic that I replaced the entire brake system in, and it has a little air in it I'm sure. I swapped in ABS components, it was not an ABS car, but it is now. I installed two rear lines(it's a four channel ABS system), plus MC and the ABS pump etc. I bled it normally, that was back before it was well known that some ABS systems had to have a special tool to get air out of the pump. That car is drivable but the pedal is just a bit softer. I own two 95 Crown Vics, so I know what they should feel like, the other came with ABS.

 

[storlied]

Got the truck running and driving again. Bled the brakes but they feel like crap.. will have to go back out and do it again. Turns out rear pass line was blown, then I replaced that... then found the front driver's blown... ugh... and then I also found both bolts/sliders for the rear pass caliper were BENT... yes bent.. lol.. replaced those.... this truck had a hellish weekend.. *whew* I thought this thing was done for...

MC - check
Radiator - check
All the lines, bolts n broken crap - check

All I got left now really is the transmission, header panel and headlights... and grill later one.. grill isn't too important but yeah...

 

[CDW6212R]

Keep busy, live longer.

 

[storlied]

She just needs some luvin, I ain't done yet.