magicjack

Last weekend I performed a brake flush and now I have a mushy pedal (I need to press the brake pedal further down to engage the brakes).

I assume I got air in the master cylinder. I used a motive pump to pressurize the reservoir and flushed with intermittent refills of the reservoir.

Any pointers to getting the air out? I was thinking of rebleeding using the motive and performing a pump of the brake pedal to expel air/fluid in the master cylinder while the car is on.

JW911

You are supposed to fill the motive with brake fluid and it automatically fills the master cylinder. Thus no air. Sounds like you didn't do that? If you pushed air in through the master cylinder then it will get caught in the ABS system. You need to bleed again while cycling the ABS electronically. This would need to be done by a technician.

semicycler

I've done it the same way as you describe with the motive bleeder without issues. It's a lot less mess to use the motive just to pressurize the system, instead of filling the motive with brake fluid and then cleaning it afterwards. But you need to be very careful not to let the fluid in the reservoir get low and allow air into the system. Frequent refills of the reservoir is necessary. That's the trade off.

Brake fluid is cheap. I'd try again and see if it improves before taking it to a shop.

BIG smoke

Sounds like intermittent refills is your problem.
It just takes a few bubbles to screw the system up.
I'd try again. I don't have any fancy Motive bleeder.
Just a patient wife, with a strong left leg.

Sneaky Pete

That is the key. If you can't see the fluid level it's too late. I bleed the brakes using the dry Motive....fill the brake fluid to the top. Put the Motive on and pressurize. Watch the level and if it drops to under the normal level (say 1/2") remove the bleeder and add more fluid and keep doing this until all corners are bled. Top it off to the correct level.

I would just do another bleed. Right rear, left rear, right front and left front in that order.

Bruce In Philly

My mechanic friend noted that to tell you have air or not, pump the brake (car stopped). If the pedal level increases (becomes more shallow; less press distance) then you have air. If the travel stays consistent, then you don't have air.

I just replaced my pads, rotors, and fluid.... the brakes immediately felt mushy but that went a way in just a day or so. I did bed them in but some tell me the mushyness is a result of "green fade". I thought I screwed up and got air in the line.... I was going to re-bleed the next weekend but all is fine.

Peace
Bruce in Philly

stronbl

Being an arm chair mechanic is tough sometimes to know all the issues and hence a working solution, but based on what has been stated thus, far, I agree with Sneaky Pete - do a re-bleed. No need for a flush, but do make sure you keep the fluid level in the master cylinder between the add and full lines while you bleed. I often will do a "manual" final bleed on left front and right front by having my son or wife slowly pump the brake pedal while I collect the fluid and tighten the bleed screw. Usually gets me a pretty firm pedal at the end. Good luck.

Petza914

I use my Motive with just pressure and not fluid like Sneaky Pete and other do and as long as you're careful about never letting the resevoir run dry, it's the best (cleanest) way to do the job. This Spring when renewing the fluid in my wife's C2S, I forgot how small the resevoir is and knew immediately when I heard the air sound - s**t. Wouldn't you know I did it on the first wheel too (RR), so the most air possible into the system.

Recovering from this took me about 2 more bottles of RBF600 and multiple bleeds both at each wheel and by cycling the pumps via Duramentric pro. I'm not sure once you introduce air into the system if you can remove it all without being able to cycle the pumps either by a dealer visit or with a Durametric.

Lesson learned, err on the conservative side, stopping and repleneshing the fluid in the resevoir more frequently than less.

user 72902

Everything mentioned surely works but I fill my Motive with brake fluid since it takes a couple of minutes to clean and I've never introduced air into the system.

Saaboteur

Can I ask why others use the Motive but leave it dry? I haven't bled the brakes on my 911, but have done it on multiple cars with the Motive, with fluid in its reservoir, and never any issues.

Lvt19672

Fill the motive guys, it will prevent this from happening.

magicjack

I've tried both ways and this apparent screw up was with the dry technique. I've found it easier than the wet because its less messy, no cleaning, I think the brake fluid also stays cleaner not running through the pressurizer, you don't use excess brake fluid, and its easier in the end to titrate the reservoir level at the end.

The small Porsche reservoir does call for multiple fillings. I was going from super blue to the yellow. I'm sad to learn that super blue is no longer available in the US.

Re abs, I do have a durametric pro. I'll do a regular flush and put a pedal pump in for good measure. If its still mushy, I'll use the durametric to cycle abs pump (its seems a bit complicated so I am hoping to avoid.).

Thanks for the pointers.

semicycler

Motive to one-man brake bleed. Dry to avoid having to clean the Motive afterwards.

Marine Blue

Like most others I also pressurize the reservoir with the Motiv and do not fill it due to the mess.

Fluid Amount:
The longest lines will take two fills to completely clear the lines of the old fluid. The shorter lines took a single fill. The clutch slave cylinder also needed a single fill but I did it last so most of the line was already clean.

stronbl

Just guessing but ...

easier clean up and less waste of brake fluid. Of course if you add air into the system, the brake fluid saving is lost as you need additional fluid to remove the air.

I've done it both ways. The fluid in Motive is the best method, but once at the track I needed a quick bleed, so I just used pressure.