Browning Posted June 17, 2015 Report Share Posted June 17, 2015 Is there any way from keeping air from getting into the ABS modulator? Tonight is the first I have read about the possibility of needing a scan tool to bleed the lines after changing a master cylinder. Only scan tool I have is a cheap one that I am sure will not work. I've changed MC's on older vehicles that allowed me to use the pump, hold and crack the breeder lose method but apparently that won't suffice? Quote Link to comment Share on other sites More sharing options...
aussiek2000 Posted June 17, 2015 Report Share Posted June 17, 2015 Its been my experience that as long as the ABS hasn't cycled, you wont get air into it. Quote Link to comment Share on other sites More sharing options...
Cordell Posted June 17, 2015 Report Share Posted June 17, 2015 If you do a good job bench bleeding the master and don't have the system open for very long ypu stand the best chance of not having any issues. I can't say I've specifically done a cavalier but I get away without cycling the abs on most GMs that I do. Now if you had one of those neat reverse bleeders (never tried but I want one) it would keep air from ever getting to the ABS. Quote Link to comment Share on other sites More sharing options...
Browning Posted June 17, 2015 Author Report Share Posted June 17, 2015 Its been my experience that as long as the ABS hasn't cycled, you wont get air into it. If you do a good job bench bleeding the master and don't have the system open for very long ypu stand the best chance of not having any issues. I can't say I've specifically done a cavalier but I get away without cycling the abs on most GMs that I do. Now if you had one of those neat reverse bleeders (never tried but I want one) it would keep air from ever getting to the ABS. Thank you both. I'll admit I'm nervous. I really hope I don't have to take it some were after swapping it out to have it bled. Quote Link to comment Share on other sites More sharing options...
Trouble Maker Posted June 17, 2015 Report Share Posted June 17, 2015 The issue isn't generally if you get air into the ABS unit, it's if you get air into parts of the ABS unit that aren't normally open to the regular fluid flow path. The air can sit in there and eventually get into the 'normal' part of the brake fluid circuit. If you get a bit of air into that part of the ABS unit, you may be able to activate ABS a few times to get the air into a part of the circuit that's in the normal flow path. I worked at an ABS maker doing testing for about 8 years and we rarely worried about cycling the unit during brake system parts swaps. It's usually only necessary if you are putting a dry ABS unit in or like Scott said, leave it open for a long time. Once our ABS test units were wet we just put screw caps on inlets/outlets when they were out of the car, then put them back in when we needed to test that unit. Even if you didn't bench bleed the air from the master cylinder, it should only introduce air into the 'normal' part of the ABS unit. Bench bleeding the master cylinder probably helps more for the generally bleeding process than anything, just like in a non ABS cars, it's can be a PITA to get the MC to bleed in the car. The in valves are normally open and the fluid normally flows that way. Normally the ABS unit just acts like a brake fluid line for you. Unless it activates then fluid flow through the part of the unit by the out valve, pump, reservoir. This is the part where air can get into that's bad. When you 'cycle' the unit, this is where we are trying to get air out of and fluid into. http://www.wiringdiagrams21.com/wp-content/uploads/2012/11/AcuraRSXABSModulatorSystemSchematicDiagram.jpg Quote Link to comment Share on other sites More sharing options...
Browning Posted June 17, 2015 Author Report Share Posted June 17, 2015 The issue isn't generally if you get air into the ABS unit, it's if you get air into parts of the ABS unit that aren't normally open to the regular fluid flow path. The air can sit in there and eventually get into the 'normal' part of the brake fluid circuit. If you get a bit of air into that part of the ABS unit, you may be able to activate ABS a few times to get the air into a part of the circuit that's in the normal flow path. I worked at an ABS maker doing testing for almost 8 years and we rarely worried about cycling the unit during brake system parts swaps. It's usually only necessary if you are putting a dry ABS unit in or like Scott said, leave it open for a long time. Once our ABS test units were wet we just put screw caps on inlets/outlets when they were out of the car, then put them back in when we needed to test that unit. Even if you didn't bench bleed the air from the master cylinder, it should only introduce air into the 'normal' part of the ABS unit. Bench bleeding the master cylinder probably helps more for the generally bleeding process than anything, just like in a non ABS cars, it's can be a PITA to get the MC to bleed in the car. The in valves are normally open and the fluid normally flows that way. Normally the ABS unit just acts like a brake fluid line for you. Unless it activates then fluid flow through the part of the unit by the out valve, pump, reservoir. This is the part where air can get into that's bad. When you 'cycle' the unit, this is where we are trying to get air out of and fluid into. http://www.wiringdiagrams21.com/wp-content/uploads/2012/11/AcuraRSXABSModulatorSystemSchematicDiagram.jpg Great info, thank you. I think I can bench bleed another master no problem. One thing I didn't find was, if air does get into the modulator or whatever it is, will it kick a light, or will the pedal just not build? I read on a couple forums that the part of the ABS you don't want to get air into actually sits higher than the master cylinder. I'm not sure yet as I haven't went and looked at it. It's my moms car. I wish I had a bleeder tool, instead of having some one pump the brake while I loosen the bleeder. Perhaps this would be a good time to purchase one. Quote Link to comment Share on other sites More sharing options...
Trouble Maker Posted June 17, 2015 Report Share Posted June 17, 2015 I can't imagine anyone has a detection scheme for this. No real way to 'sense' that there is air in there. So no, I don't think there will be a lamp. I don't know every other ABS makers exact detection algorithms so I can't say 100% for sure. I'm not sure what it would gain you anyways. When that air eventually gets out into the 'normal' part of the brake fluid circuit, it would make the pedal spongier. Maybe at first until that happened, when the ABS tried to work it wouldn't work as well. It would seem strange to me that any part of the ABS unit would be above the master-cylinder. You always want each next part of the circuit to be 'downhill', or else it's difficult to impossible to bleed. Quote Link to comment Share on other sites More sharing options...
Browning Posted June 17, 2015 Author Report Share Posted June 17, 2015 Thanks. If this rain would die down for a little bit I am going to drive over and see if I can get it replaced without much issue. Doesn't look like it's going to give me any window to work with. Quote Link to comment Share on other sites More sharing options...
Browning Posted June 17, 2015 Author Report Share Posted June 17, 2015 Pulled the old one,removed the res., installed it on the new MC and bled it before putting it on the car. Haven't had much chance for bleeding lines yet but still no pedal at all, nor can it be pumped it. To the floor every time. Pouring rain again so I can't try bleeding it out to see if it makes a difference, but even with a bunch or air in the lines shouldn't it still pump and hold pressure? Petal is a lot harder like it should be when pumped with the key off, but it still can be put to the floor. Quote Link to comment Share on other sites More sharing options...
Browning Posted June 17, 2015 Author Report Share Posted June 17, 2015 I've checked the rubber lines and none are swelling up when the pedal is pressed, and there'sno fluid on the back of the rear wheels so I wouldn't suspect wheel cylinders. I haven't found any leak at all and I am wondering if the new MC is defective. Quote Link to comment Share on other sites More sharing options...
Trouble Maker Posted June 17, 2015 Report Share Posted June 17, 2015 I really think you have to bleed the whole system before you get to that point? Maybe I missed something but it sounds like you didn't bleed the system yet due to no 2nd person? Quote Link to comment Share on other sites More sharing options...
Browning Posted June 17, 2015 Author Report Share Posted June 17, 2015 yea I haven't been able to yet. I assumed there would be at least some difference just with the new MC installed. I'll have to bleed it all tomorrow when I get a helper and these stripped bleeders off. lol Quote Link to comment Share on other sites More sharing options...
ecc_33 Posted June 17, 2015 Report Share Posted June 17, 2015 Easiest way to bleed brakes by yourself is a pepsi 20oz bottle and a tight hose over the bleeder. Cut a hole in the top of the top of the bottle cap or just put the hose into the bottle with about half full of fluid. Crack bleeder open and begin to pump brakes. Usually go from the right rear to left rear. Then to right front. Then left front. It might not be perfect but when in a pinch its better than no pedal at all. sometimes just cracking the bleeders all open just barely and letting them gravity bleed helps too. Quote Link to comment Share on other sites More sharing options...
Cordell Posted June 17, 2015 Report Share Posted June 17, 2015 Yeah there is air in the lines, just bleed it. If you can't get someone to help the process described above works well, I bleex brakes by myself quite often. Quote Link to comment Share on other sites More sharing options...
Browning Posted June 18, 2015 Author Report Share Posted June 18, 2015 I couldn't get those bleeders on the calipers to budge, then both broke, even after soaking for a couple hours. Got an easy out and snapped it. Good thing though, as I noticed the seals on the caliper looked pretty wore out and she was due for pads anyway. I swung by advance on the way home and picked up a couple remans and pads for it. She should have her car back on the road tomorrow, unless that modulator decides to be an ass and I need to call a shop lol Quote Link to comment Share on other sites More sharing options...
Browning Posted June 18, 2015 Author Report Share Posted June 18, 2015 When using a soda bottle like that, I assume the hose needs to be submerged in the fluid? Do I just crack open the bleeder, then go inside the car and bump a few times, tighten the bleeder then move to the next, rinse and repeat? Quote Link to comment Share on other sites More sharing options...
Cordell Posted June 18, 2015 Report Share Posted June 18, 2015 When using a soda bottle like that, I assume the hose needs to be submerged in the fluid? Do I just crack open the bleeder, then go inside the car and bump a few times, tighten the bleeder then move to the next, rinse and repeat? Yes, you pretty much got it. Quote Link to comment Share on other sites More sharing options...
Browning Posted June 18, 2015 Author Report Share Posted June 18, 2015 Thank you. I might give that route a try. Quote Link to comment Share on other sites More sharing options...
Green Bastard Posted June 18, 2015 Report Share Posted June 18, 2015 When using a soda bottle like that, I assume the hose needs to be submerged in the fluid? Do I just crack open the bleeder, then go inside the car and bump a few times, tighten the bleeder then move to the next, rinse and repeat? Yes, the hose needs to be submerged in fluid. The idea is you pump the pedal until you cannot see bubbles anymore (that may prove to be difficult on the passenger side though). Quote Link to comment Share on other sites More sharing options...
Browning Posted June 18, 2015 Author Report Share Posted June 18, 2015 This thing is pissing me off.I can bleed rear passenger fine, can barely get anything out of rear driver side.Passenger front is dry as can be, and driver front bleeds fine. No matter what I do nor how many times I try to bleed rear driver,and front pass, there is no change. Not sure about the rear left but I am wondering if the rubber hose on the front pass is collapsed? I have it soaked going to try and break the nut free just above it to see if there's fluid at that point. Hopefully. Quote Link to comment Share on other sites More sharing options...
Browning Posted June 18, 2015 Author Report Share Posted June 18, 2015 I can't even get any from the front passenger line with the line unbolted from the caliper. Quote Link to comment Share on other sites More sharing options...
Browning Posted June 18, 2015 Author Report Share Posted June 18, 2015 Any of you used one of these to push air up, instead of sucking it out? http://shop.advanceautoparts.com/p/powerbuilt-tools-vacuum-pump-brake-bleeding-kit-22-piece-648744/9150047-P?searchTerm=bleeder#fragment-3 Quote Link to comment Share on other sites More sharing options...
Clifford Automotive Posted July 6, 2015 Report Share Posted July 6, 2015 Looks like you got yourself into some trouble. GM need to be connected to a scanner and done properly when you get into that kind of repair. This wasnt a simple pad job. I can also tell you without clicking the link above that, thats a vacuum pump. Nothing pushes air into the system, it only draws out. You need to have this thing towed over to you nearest repair shop. Quote Link to comment Share on other sites More sharing options...
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