1987Porsche944WithRealLongName

My car sat for a few years with old fluid and pads and although its running now I still for the life of me can't get rid of this mushy pedal. I've pumped a good gallon of brake fluid through the system trying to bleed it and I've replaced the master cylinder just to see if it had anything to do with it. I've bled every way, the foot-pump method, the speedbleeders, I even used a powerbleeder this last time and really let it have it smacking the calipers with a hammer to free up bubbles. No change in anything. The calipers aren't frozen and the clutch works fine.

Pretty bad when a beat up old acura puts my porsche's brakes to shame, I can't get close to locking these up.

Arominus

Have you replaced the hoses? if they are old they will expand.. and bam. Mushy pedal. Get the stainless replacements, they are decently cheap and will help.

Also, once you've flushed all of the old fluid out you can just dump the fresh fluid back into the master cyl during bleeding as long as you've cleaned out your bleed cup.

HICKS

+1 on new brake lines, even if you get the oem rubbers.

God_Bot

I have a slightly leaky bleeder on a rear caliper which allows a bit of air to get into my lines. Even with a little air I can easily stop when I press the brake pedal to being level with the gas pedal and can lock up the brakes with full extension of the pedal.

I would say lines or possibly something within the master cylinder like a leaky seal. That would probably cause issues with the clutch though.

1987Porsche944WithRealLongName

When I first started getting the car running the brake pedal was hard as a rock and not in a good way. Maybe while pushing the pedal down hard it strained the rubber lines, what's an easy way to check them?

Also the n/a and turbo lines are interchangeable right? I planned on upgrading the brakes when I get it in the budget anyway.

Jfrahm

Do you have ABS? Also it sounds like an NA although you do not say.

One thing you can do is to pin the brake pedal down for hours or overnight and then bleed a corner. Leaving the system under pressure makes the bubbles a lot smaller and they migrate out more easily. You also learn a lot if the pedal does not stay firm.

With a board across the front of the seat you can use another board to depress the brake pedal. Get the pedal down and leave it overnight, then bleed the LR. Just one shot. Then pin the pedal down again and leave it all day. Then bleed the RR. Then put the pedal down all night and bleed the RF in the AM. And so on.

If you have ABS the pump is a good place for air to hide also.

God_Bot

If you're not losing any fluid then you can rule out any leaks. If it brakes in a straight line without any pulling then you can usually rule out a crushed line. ABS could also be causing issues, but I don't have it so couldn't help you there.

Rubber lines will always balloon slightly, I imagine that if something broke in them allowing for a mushy pedal that you'll be able to see where they were ballooning if you have a helper.

jthwan22

I bleed the ABS pump by braking on gravel road (local park driveway). After several ABS activation, I bleed the brakes normal again. The bubbles are now down stream of ABS pump. Some newer cars uses expensive factory tool to activate ABS pump. I don't know if Porsche has such factory tool.

Or you can try reverse bleed
http://www.jegs.com/p/Phoenix-System...80478/10002/-1

1987Porsche944WithRealLongName

Yeah its an n/a- no abs

Stuck a broom handle on the brake pedal and left it all night. Bled the 2 rear brakes and the passenger front a little and didn't feel any change. I noticed no weird things with the brake lines.

One thing I did notice is that pushing the pedal down to build pressure was easier when I was bleeding the front, the back had a stiffer pedal as I pumped down.

I have a nice stiff clutch pedal but could there be air in it somehow interfering with the brakes instead? I doubt it but at this point I'm beginning to get desperate.

fwb42

Are your calipers "centering" when breaking? Are they free to move? If a caliper hangs the breaking will be only on one side of the rotor.

Jfrahm

It takes at least two days to use my method. You can only do one corner per application. I don't know if it'll solve your problem but carefully trying to squeeze any bubbles down small and shoot them hard out the bleeder is the key.

Did you bench bleed the MC? If not you might have air hiding in there. Sometimes the MC comes with the bench bleed kit.

Andrewporsche

Ive been told you must get the rear of the car as high as possible and the front as low as possile when bleeding the brakes..

kens_74911s

I hope you are onto this but but it worth stating. You need to make sure you bleed the RT/RR then LT/RR followed by RT/FT , LT/FT. Start furthest from master then work back from there. K

MAGK944

MC needs to be bench bled as mentioned. If you didn't do this you might try bleeding the brakes with a pressure bleeder while pumping the pedal and tapping the MC with a small hammer. This normally releases any air bubbles without having to remove it again. You will need assistance but it's worth a try.

Definitely worth changing the flex lines if you haven't done this. Good condition na brakes are some of the best I've felt on any car.

1987Porsche944WithRealLongName

Yeah I bench bled my master.

Would it be a good idea to pressurize my system with a pump and then stab on the pedal to knock any bubbles loose?