Brake bleed issue (reoccurring)
 

I just changed out my front calipers and apparently I didnt bleed the brake system correctly because my pedal goes all the way to the floor. I feel like a crazy person because I use so much fluid and cant seem to get it right.

First of all, I'm using a Motive power bleed system which hooks up to the master cylinder and keeps pressure positive pressure at the resivour so you can bleed a system by yourself. So after the caliper install I hook up the bleeder, pressure holds steady, and I fill up both calipers. Then I go through and bleed the whole system, left rear - front right - rear right - front left. The first caliper (Rear Left) never shows any bubbles.... ever... I put almost a liter of fluid through it and never any bubbles. So, Im like 'whatever. thats enough, moving on". I bleed the rest of the system, few minor bubbles here and there, no big pockets which I thought was strange, but I finish up with the front left caliper.
Time to check the brake pedal. Good pressure. Start the car, pedal goes all the way to the floor. I haven't seen any manual or youtube that says you need to bleed with the car on, so why would that matter?

I bleed the whole system again. Same situation, no bubbles at the first caliper (after like 1/2 a liter this time), and no bubbles anywhere else actually. Finish up at the front left, check the pedal, feels good, turn the car on and straight to the floor.

I gotta say that this has happened to me before and I it drives me crazy. I just keep messing with the system and blowing through crazy amounts of brake fluid until eventually the system just works. Idk how, but in the past if I just keep messing with it it works.

No evidence of leaks anywhere. Any advice?

Jr

prob have air in the abs unit

Always bleed the system with the car running (for vacuum assist) (EDIT: This only applies to traditional 2-person pedal style bleeding). Bleed starting with the furthest caliper from the MC, end on the nearest caliper to the MC, meaning you should bleed both rear calipers first (passenger side then drivers side), then both front calipers (pass side, driver side). The pedal will sometimes go to the floor after you're done bleeding - this is just the system re-building pressure (since you released all the pressure when you opened the bleeder valve) as well as pushing the pistons into the back of the pads (and the pads into the rotors). If you start the car and are able to build pressure after a couple pumps (after which the pedal remains firm) then you are fine.

Motive alone wont get all the air out, you need to use the pedal also.

If you are trying to get stubborn bubbles out, or just trying to be thorough...the best bet is to use a combination of both methods.

All wrong


there is a specific order they need to be done and it's not the furthest one thing. After I could not get my Akebono to brake right I finally looked at the brake bleed book at work


now my help is over because I don't remember it lol


lastly for the record.......gravity bleeding gave be the best pedal

In the attached image you can see the drive rear is the furthest from the MC in terms of line length, and following the 'old school' method of furthest -> closest would mean a drive rear, pass rear, pass front, drive front bleed order. So the FSM recommended order starts with the longest line (drive rear), then goes 2nd -> 3rd longest lines (pass front, pass rear), and finishes with the shortest (drive front). Why Nissan recommends this is beyond me, but they did design the car, so I'm inclined to believe them.

Regardless - OP, I'd recommend re-bleeding with the pedal method using the FSM order again, and try tapping on the calipers with a mallet before and as you crack the bleeder to free up any stubborn bubbles.

https://cimg2.ibsrv.net/gimg/my350z....db45f9ee0b.jpg

:+1:

Forgot to mention the mallet tappy tap. Obviously, you don't need to bang the nuts out of it, but just some gentle persuasion to release any bubbles that may be lodged somewhere in the caliper.