Help figure out why brakes are mushy and non-responsive after pad change

[Mocoso]

Ok so I changed the pads today on both fronts and noticed that the brakes felt somewhat mushy... during the bed-in process I had one run where pedal hit the floor and brakes didnt respond....that put an end to the bed-in process

Obviously this sounds like air in the brake line and I will bleed the lines tomorrow morning - I just want confirmation that this is the most likely suspect.. what bugs me is that I didnt disconnect any of the brake lines so I dont get how air could have gotten into the lines to begin with

I may be missing something as basic as "you push the piston in you must bleed the lines" - the only thing I know we screwed up on is I didnt notice friend who was helping me had unscrewed the fluid reservoir cap and I pumped the brakes to relieve pressure before removing the calipers. Could this have induced air into the line?

Yes this is my first DIY brake job... road I did bed in is behind my house and its a 2 lane divided straight road with no traffic at the time I did the bed-in (may be a rookie at changing brakes but I wasnt being stupid and risking others lives during bed-in)

Any help or confirmation that bleeding the lines should be the first thing to do would be appreciated

Thanks

 

[Kain]

The first thing that always comes to my mind when someone mentions mushy brakes or clutch pedal is air in the lines. However, I haven't changed the pads on this car yet, but I'm wondering if you had to compress the caliper piston to get the new pads in? If so, the piston might not have been fully compressed, but this would just make the brakes too grabby. So yes, bleeding the lines should help.

 

[ZyrehT]

I also don't recommend pushing in pistons without cracking the bleeders. Brake systems weren't designed for reverse flow.

 

[shane02pro5]

Bleeding the brake lines takes about a minute to do all 4 corners. Not sure exactly how the ms3 is but with the cap off air will not be able to be sucked in but maybe overflowed some fluid out. Either way fill the reservoir and pump the brakes several times and loosen the bleed screw on one corner at a time just to let the air out then retighten and repeat unil you immediately get only fluid coming out. Be sure to add more fluid during the process depending on the amount of air that was in there the level may drop significantly.

 

[BOOSTR]

R&R pads w/o bleeding will cause your condition. Get the air, moisture and old fluid out. Bleed each wheel with a hose connected to the bleeder in a container with fresh fluid. Top off your resovoir with fresh fluid each time, don't let it run dry. Your pedal should be normal after complete bleeding.

 

[Kain]

Just to add to everyone else since we're all on the same page with this, I would do a complete flush and install speed bleeders while you're at it. Also, bleed from the caliper farthest from the master cylinder and work your way to the closest.

 

[Mocoso]

Thanks everyone - seems like we all agree its air.. Ill bleed the lines today - wont get drastic on the flush just yet as Im planning on adding braided lines and will do so at that time but if simple bleed doesnt do it that may be the next step