Brake Problems HELP PLEASE!
Thread Starter
Instructor
Joined: Mar 2003
Posts: 156
Likes: 0
From: SOCAL
Brake Problems HELP PLEASE!
Hey guys, Alrite, I'm having a problem with braking on my 993, the brake pedal seems to get soft all the way to the bottom and I must pump the brake the second time to get a firmer pedal feel. I bleed the brakes in the rear and took some bubbles out till it was gone.
I then went to the front of the calipers...this is where the problem was...when i was bleeding the front calipers "2 hoses, one on each bleeding screw with a t fitting", after I opened and the srews and had my brother pump the pedal down..their came a stream of brake fluid and when he got to the bottom of the pedal, nothing but AIR BUBBLES!, I tried this more than 20 times and the outcome was the same. I tried the other caliper to see if it was just that but it did EXACTLY the same with the air bubbles at the end. I swapped all Brake fluid out and its CLEAN as a whistle BUT still has air bubbles and pedals feels spongy and soft. I for sure filled up the reservior to make sure their was always brake fluid in it. Could it be the calipers? PLEASE HELP ME thanks!
chris
I then went to the front of the calipers...this is where the problem was...when i was bleeding the front calipers "2 hoses, one on each bleeding screw with a t fitting", after I opened and the srews and had my brother pump the pedal down..their came a stream of brake fluid and when he got to the bottom of the pedal, nothing but AIR BUBBLES!, I tried this more than 20 times and the outcome was the same. I tried the other caliper to see if it was just that but it did EXACTLY the same with the air bubbles at the end. I swapped all Brake fluid out and its CLEAN as a whistle BUT still has air bubbles and pedals feels spongy and soft. I for sure filled up the reservior to make sure their was always brake fluid in it. Could it be the calipers? PLEASE HELP ME thanks!
chris
Passed On
Rennlist Member
Rennlist Member
Joined: May 2001
Posts: 3,031
Likes: 3
From: Pittsburgh, PA
You might have screwed up the master cylinder.
NEVER NEVER NEVER, NEVER use the brake bleed method your Grandpa used on his '48 Buick. That means having "Dumb" pump the brake pedal while "Dumber" opens and closes the bleed screws. Get one of those Motive Power Bleeders and do it right.
How do I know?
a) In the 993 shop manual (if you weren't too cheap to buy one, and could find one if you weren't so cheap), Porsche issues a warning to NOT pump the brake pedal fully when trying to take up the slack in the brake pedal by having the brake pistons engage the brake pads after changing pads. Use several short pumps. To me it's to save the master cylinder.
b) Ages ago I had a '76 Porsche 911S which I initially bled the brakes using your "Dumb and Dumber" method. Well, I went through two master cylinders in less than a year! Warning was that on initial brake application the pedal was soft; one pump and the pedal was OK. No amount of bleeding could correct this. On second master cylinder failure I toook it apart, and noticed that the primary and secondary brake circuit rubber piston seals tend to wear a "groove" in the master cylinder bore based on their normal movement during regular brake application. This forcing of the pedal to the floor during bleeding forced the piston seals past this normal wear pattern and prematurely destroyed them. I switched to pressure bleeding like the Motive product and never had another master cylinder failure in almost 25 years of driving one vehicle or another.
Haven't a clue what a Power Bleeder is? Look at the pretty picture.
<a href="http://www.motiveproducts.com/" target="_blank">http://www.motiveproducts.com/</a>
Try this and see what happens with your bleeding. Hopefully there isn't any internal damage and all you need is a good bleed tool.
NEVER NEVER NEVER, NEVER use the brake bleed method your Grandpa used on his '48 Buick. That means having "Dumb" pump the brake pedal while "Dumber" opens and closes the bleed screws. Get one of those Motive Power Bleeders and do it right.
How do I know?
a) In the 993 shop manual (if you weren't too cheap to buy one, and could find one if you weren't so cheap), Porsche issues a warning to NOT pump the brake pedal fully when trying to take up the slack in the brake pedal by having the brake pistons engage the brake pads after changing pads. Use several short pumps. To me it's to save the master cylinder.
b) Ages ago I had a '76 Porsche 911S which I initially bled the brakes using your "Dumb and Dumber" method. Well, I went through two master cylinders in less than a year! Warning was that on initial brake application the pedal was soft; one pump and the pedal was OK. No amount of bleeding could correct this. On second master cylinder failure I toook it apart, and noticed that the primary and secondary brake circuit rubber piston seals tend to wear a "groove" in the master cylinder bore based on their normal movement during regular brake application. This forcing of the pedal to the floor during bleeding forced the piston seals past this normal wear pattern and prematurely destroyed them. I switched to pressure bleeding like the Motive product and never had another master cylinder failure in almost 25 years of driving one vehicle or another.
Haven't a clue what a Power Bleeder is? Look at the pretty picture.
<a href="http://www.motiveproducts.com/" target="_blank">http://www.motiveproducts.com/</a>
Try this and see what happens with your bleeding. Hopefully there isn't any internal damage and all you need is a good bleed tool.
Thread Starter
Instructor
Joined: Mar 2003
Posts: 156
Likes: 0
From: SOCAL
sweeetttt..thank you sir. The pedal was like this before but this was the first time i tried to bleed it. Hopefully i didnt do any damage either it still breaks the same a little Thanks@!
chris
chris
Addict & Guru
Rennlist Member
Rennlist Member
Joined: May 2001
Posts: 3,897
Likes: 3
From: St. Louis
chris
Do a quick Google.com search for "how to bleed brakes" & you'll find specific instructions. For instance, here's an article on <a href="http://www.spswebpage.com/tech/bleeding_brakes.html" target="_blank">How to Bleed Brakes – The Right Way.</a>
As a partial comment on your "technique:"
Do 1 bleed screw at a time since it's less likely you'll "screw" it up. The bleed order should be RR outside, RR inside, LR/o, LR/i, RF/o, RF/i, LF/o & LF/i, i.e., moving closer to the brake fluid reservoir. The rest is as set out in this article & others. My guess is if you haven't already damaged a seal in the master cylinder, you have a screw undone (loose?) while your brother is releasing the pedal & sucking air into the system. It'll never work that way.
BTW, a Motive bleeder would make the job easier & more foolproof.
Do a quick Google.com search for "how to bleed brakes" & you'll find specific instructions. For instance, here's an article on <a href="http://www.spswebpage.com/tech/bleeding_brakes.html" target="_blank">How to Bleed Brakes – The Right Way.</a>
As a partial comment on your "technique:"
Do 1 bleed screw at a time since it's less likely you'll "screw" it up. The bleed order should be RR outside, RR inside, LR/o, LR/i, RF/o, RF/i, LF/o & LF/i, i.e., moving closer to the brake fluid reservoir. The rest is as set out in this article & others. My guess is if you haven't already damaged a seal in the master cylinder, you have a screw undone (loose?) while your brother is releasing the pedal & sucking air into the system. It'll never work that way.
BTW, a Motive bleeder would make the job easier & more foolproof.
Drifting
Joined: May 2001
Posts: 2,224
Likes: 24
From: Indiana
You may want to check out this thread also. In case any of this took place.
<a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic;f=3;t=009486#000009" target="_blank">mushy brakes - when fluid drained and ABD</a>
<a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic;f=3;t=009486#000009" target="_blank">mushy brakes - when fluid drained and ABD</a>
