Brake bleeding tips needed - still have a spongy pedal

[stevehifi]

Hi Guys,

I did a brake flush last night, ended up with a nice firm pedal. (I used motive power bleeder and just to be safe did a 2 person bleed (3 x5 pump) on each corner).

Unfortunately, this morning I ended up with a squishy soft pedal. Now if I try to brake hard I lack the travel/feel I need and end up having the ABS kick in abruptly due to
the inconsistent pressure.

I do have MPP SS lines installed, I checked all the fittings and there are no leaks, also the reservoir is full and hasn't changed in level.

I'm guessing there is still air in the system somehow or perhaps there was air in the ABS/DSC pump that wasn't cycled properly?

Just wondering if anyone has gone through this scenario, and how you dealt with it.

Thanks,
Steve

 

[Pricedm]

Not really any help as I also did a bleed recently using the Motive bleeder, but had no issues at conclusion of the service. For troubleshooting, maybe remove the brake fluid reservoir cap, have assistant repeatedly cycle the brake pedal, and monitor for air bubbles? After that if it were me, I'd probably crack open a new bottle of brake fluid and re-do the fluid change.

Another post here (P3 Brake Job) listed the brake caliper order as driver front, passenger front, passenger rear, driver rear.
BTW I used ATE SL.6 DOT 4 since I already had fluid in the Motive bleeder from doing my Volvo prior to the Tesla. Two year change interval for DOT 4.

Good luck and post back your resolution.

 

[Lindenwood]

After replacing all lines and front calipers, it took a full round with the motive bleeder…..and then a second full round with the motive bleeder…to get a firm pedal.

I personally wouldn’t bother with pumping after this experience (which was very positive given I did it all 100% by myself).

 

[stevehifi]

seems like its a bit firmer after I triggered some hard stops when the ABS kicked in a couple times. Maybe cycling the ABS or traction control a bit helps move the fluid/air out of the system.

 

[dsgerbc]

If you have performance brakes, make sure to bleed both sides of the front calipers.

 

[joe.smith]

seems like its a bit firmer after I triggered some hard stops when the ABS kicked in a couple times. Maybe cycling the ABS or traction control a bit helps move the fluid/air out of the system.

I’m just a little confused. Why would you use a pressure bleeder and then have someone pump the brakes? Also, you pontificated that the system had move air out of the system by cycling the ABS system? So, where do you suppose that air went? It’s a sealed system so if there was air, it’s still in your system. Maybe you should flush your system again with the power bleeder and this time don’t have anyone pump the brakes? I’d hate for air to be ‘lurking’ in your system and you get that ‘squishy’ feeling at the absolute wrong time.

 

[Sophias_dad]

If you have performance brakes, make sure to bleed both sides of the front calipers.

Pretty sure even non-performance front brakes have bleeders on both sides of each caliper.

 

[Occhis]

You may have some air trapped in the ABS module. If that is the case it will likely require a trip to the service center.

 

[Lindenwood]

Oh! Yes, standard advice is to re-bleed the brakes after activating ABS a few times to ensure any bubbles that entered that system are pushed out.

 

[Occhis]

Re-bleeding does not expel air trapped in the ABS, if that’s your specific issue. You need special tool or compatible OBD2 scan tool.

 

[stevehifi]

I’m just a little confused. Why would you use a pressure bleeder and then have someone pump the brakes? Also, you pontificated that the system had move air out of the system by cycling the ABS system? So, where do you suppose that air went? It’s a sealed system so if there was air, it’s still in your system. Maybe you should flush your system again with the power bleeder and this time don’t have anyone pump the brakes? I’d hate for air to be ‘lurking’ in your system and you get that ‘squishy’ feeling at the absolute wrong time.

Just to add some clarity:
-I installed the MPP.R BBK and changed the lines to MPP
-I did leave the old lines drip the fluid out for a while before installing the new lines (this may have introduced way too much air into the system)
-I did two flushes with the Motive power bleeder
-I did a final 2 person pump/bleed process on all 4 corners
-Pedal was firm after that
-After driving around a couple days, cycling ABS pedal is still soft.. brakes still work well but it's no where near the firmness it should be

I will try one more flush to see if that resolves the problem.

 

[stevehifi]

Re-bleeding does not expel air trapped in the ABS, if that’s your specific issue. You need special tool or compatible OBD2 scan tool.

I'm not sure if many people experience this issue, it was just a hypothesis. If the dealer is the only place that can bleed then I guess that will be
my last resort although they may or not work on a car with aftermarket brakes.

 

[Occhis]

If the fluid level in the master cylinder got too low while fluid was dripping, so that the MC did not have sufficient fluid to keep air from entering the system, I’d say air got in that way and worked it’s way into the ABS. That may explain that the pedal was firm on the test drive, but next day it was soft. It took a few stops for the air to work it’s way to the ABS and now it’s trapped there.

 

[Pricedm]

@Occhis is there a DIY solution for getting air out of the ABS unit? If a scan tool is required, do you have a favorite you can recommend? thanks

 

[Aggmeister2010]

Hey Folks, I have this identical issue on my Model S. Installed a BBK with SS lines, bled the fronts (not the rears yet, though i will do a full round in the morning) with a motive power bleeder, and have a soft pedal that goes to the floor.

Curious if @stevehifi found a solution...my master cylinder never got low on fluid, but i'm not sure about any implications regarding the ABS pump.

 

[stevehifi]

Hey Folks, I have this identical issue on my Model S. Installed a BBK with SS lines, bled the fronts (not the rears yet, though i will do a full round in the morning) with a motive power bleeder, and have a soft pedal that goes to the floor.

Curious if @stevehifi found a solution...my master cylinder never got low on fluid, but i'm not sure about any implications regarding the ABS pump.

After I put the MPP.R kit on the rear and swapped all pads to pagid RSL29 I don’t have the issue anymore. The pedal is rock solid.

Make sure you do a double brake flush if you install a BBK.

 

[Aggmeister2010]

After I put the MPP.R kit on the rear and swapped all pads to pagid RSL29 I don’t have the issue anymore. The pedal is rock solid.

Make sure you do a double brake flush if you install a BBK.

Interesting. Do you think it was doing a full bleed after installing the rears that did it?

 

[Sophias_dad]

Hey Folks, I have this identical issue on my Model S. Installed a BBK with SS lines, bled the fronts (not the rears yet, though i will do a full round in the morning) with a motive power bleeder, and have a soft pedal that goes to the floor.

Curious if @stevehifi found a solution...my master cylinder never got low on fluid, but i'm not sure about any implications regarding the ABS pump.

Unless the S is unusual, brake circuits are usually diagonally paired on modern automobiles. Having the rear unbled on both diagonals means you'll have awful brake behavior.

 

[joe.smith]

Hey Folks, I have this identical issue on my Model S. Installed a BBK with SS lines, bled the fronts (not the rears yet, though i will do a full round in the morning) with a motive power bleeder, and have a soft pedal that goes to the floor.

Curious if @stevehifi found a solution...my master cylinder never got low on fluid, but i'm not sure about any implications regarding the ABS pump.

I've got a question regarding your statement "my master cylinder never got low on fluid". When using the Motive Power Bleeder, how does this ever come into play? Or, did you mean you never allowed the actual power bleeder level to go low? Also, how much fluid did you go through to bleed your system?

When I used the Motive Power Bleeder, I was surprised at how much fluid it took me to completely flush my system. As a matter of fact, I had to go back to the store for more. In the end, it took on the order of 96 ounces (give or take) to bleed all 4 brakes. The other discovery was just how hard it was to establish a good seal with the Model S master cylinder adapter.

Obviously, you've gotten some air into your system. Someone else can chime in, but I don't think each 'channel' (brake location) is isolated. So, could you have gotten air into one of the lines you weren't doing (back) while bleeding the other (front)?

 

[Occhis]

WOW! 96 ounces is a LOT of fluid. I’ve flushed brake fluid on several cars with a power bleeder, and it’s never taken more than 1-2 pints.