So, I reinstalled my newly sleeved and sealed brake master cylinder, and bled all the brakes, plus the ABS actuator in the correct order. The good news, no more leaks in the engine bay and the brakes work. The bad news, the brake pedal has a spongey feel compared to the firmness that I was used to. So obviously my bleeding was not as thorough as I thought and I must still have air trapped in the lines somewhere. I bled about 1 - 1.5 liters of brake fluid to bleed the system (used about 4-5 500 ml bottles of brake fluid to completely fill the system). I dont know if that's normally enough. How much fluid would you guys go through when brake bleeding the whole system? I've got Brembo's on the front, with two bleed nipples on each caliper. Bled both, but obviously air remains... Cant be bothered taking all the tyres off again, next time will see if I can bleed all four calipers with the wheels on.
Just check the brake bracket is on properly and not moving - check the upper bolt on the top is in not just the four bolts securing to the floor Check no fluid is coming through out the piston near the wall Then its safe to assume air in is the system still - as for that don't know - you should have bled them by 1.5 litres Is air coming back through one of the nipples when you block off? ...running out of potential causes to a bleed problem here based on using around 1.5 litres JC
Even so - 1.5 Litres would have got it done I am actually thinking the lines are seeping air - what else could it be - hence my stupid questions like - is it fitted correctly. Given he did not remove the brakes proper - rules them out for leaks but given he removed the master cylinder means potentially the lines could be loose or not fitted correctly. If the lines at the master cylinder are sucking air, not even 100 litres will fix it given its going straight into the master direct. Check your master lines again for fitting and leaking....... Not sure on your setup - but an air leaking engine bay bleed line could also do it if you have one. Just check things off systematically starting with a visual at the mount so your not chasing your tail - there's really not much else other than air entering the system somewhere once you know that side is good Cheers Jamie P.S. I tend to use a small amount of AC delco on these threads but technically you don't need to if they are serviceable
Well, this is embarrassing... Clearly I didn't read the Brake bleeding 101 guide. In the past, when I bled my brakes, I used the vacuum method. It worked well, but was never really happy with the constant small stream of bubbles in the line which I think was just air being sucked into the vacuum through the bleeder screws. In the end, the pedal was nice and firm so I wasn't worried. This time, I tried the old pumping method. But what I didn't read or understand is that at the end of each pedal depression, I should close the bleed screw before letting the pedal travel upwards and hence prevent any air from getting sucked back into the calliper. So I think whats happened, while my wife is in the car pressing the brake pedal at my command, all she's really doing is forcing the fluid and bubbles out, but then inadvertantly introducing air back into the calliper when she lifts her foot off the brake. Ooops. I also had the bleed screws quite loose so it would have been quite easy to for the air to suck back in. What an idiot. So lets do it all again, but this time I'll go back to my vacuum pump and just add some grease around the nipple to try and prevent air from getting in. I'll suck through a good amount of fluid and just close the nipple when I'm happy Ive collected enough fluid. Worked for me last time.
Speed Bleeders are the way to go. You've learnt something & also given the brake system a very good flush.
Glad you worked it out Everyone has something to learn. Not so many of us admit it after the fact. Thanks for posting the followup, I'm sure it will save somebody some hassle down the track.
Pffff. Semantics!!!!!!! Mighty VAC........! Self descriptive!!!! No need for pedantism where I come from!!! E
The 'old school' method...... If you'd kept the end of your bleeder hose submerged in the brake fluid 'catch jar' (like you're supposed to) you would have alleviated this situation. Your missus would have expelled air on the compression stroke and drawn old fluid from the jar on the return stroke (no new air entering the system). By not locking off the bleeder before the return pedal stroke, you may have just been 'see-sawing' an air pocket backwards and forwards in the brake line instead of progressively moving the air toward the bleeder
Slight thread hijack. My BMC is leaking where it attaches to the booster. Just curious if our z's have a gasket where it attaches to the booster so I'm prepared. Thanks in advance. :zlove:
No Gasket... where the BMC meets the brake booster is just a hollow or resting place for the rear of the BMC to sit in the brake booster. The BMC is a sealed unit, so no gasket there. Once you have the hard lines disconnected and all the annoying hoses out of the way, its just a case of undoing the 2 10mm bolts, move a black metal bracket, and then BMC will pop straight out.
Cheers for the follow up as I am about to put my new lines and callipers on next week when they arrive.
