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Old 03-22-2015, 01:18 PM   #1
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Sticking Brake Pedal

This problem has just developed over the last couple of days.

When applying light pedal pressure to the brake it stays down & needs to be pulled back up to disengage the brakes.

If you just very lightly touch the pedal it will actually suck itself down slightly creating more braking.

I haven't looked at the issue yet but has anyone encountered a similar issue.

My initial thoughts are master cylinder maybe.
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Old 03-22-2015, 02:08 PM   #2
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This could be caused by a brake booster problem - either a failed diaphragm or water in the booster itself or possible the vacuum line leaking.
Have you cleaned the drains at the front "frunk"?. If they are blocked then water can get into the booster and stop it operating.....
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Old 03-23-2015, 12:11 PM   #3
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Bad brake booster will cause that.


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Old 03-26-2015, 01:17 PM   #4
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Quote:
Originally Posted by Steve Tinker View Post
This could be caused by a brake booster problem - either a failed diaphragm or water in the booster itself or possible the vacuum line leaking.
Have you cleaned the drains at the front "frunk"?. If they are blocked then water can get into the booster and stop it operating.....

No I haven't cleaned the lines. Is there a DIY on how to?
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Old 03-26-2015, 07:20 PM   #5
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Details on drain cleaning can be found using the search function and see Mike Fockes Boxster Page for details.
Cleaning out drains (front & rear) is one thing, but if your drains are blocked and water has got into your booster, that's a much bigger problem......
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Old 03-28-2015, 01:06 AM   #6
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Details on drain cleaning can be found using the search function and see Mike Fockes Boxster Page for details.
Cleaning out drains (front & rear) is one thing, but if your drains are blocked and water has got into your booster, that's a much bigger problem......
Thanks Steve,

I'll have a look. So if water has got into the booster is it best tyo just replace the booster or is there more too it?
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Old 03-28-2015, 10:18 AM   #7
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Sounds like a defect master brake cylinder.

Some ideas:

Break fluid level is OK and brake fluid is new and the complete system was ventilated lately?

Do you have a MT? Was the line to the clutch slave cylinder also ventilated? If not, this sometimes causes strange effects.

Was the system ventilated correctly? Longest brake line to shortest?

Did you use a pressure system to ventilate the brake system? If you use too much pressure this can harm the ABS system. Also you can damage the fluid reservoir container. I think 1 bar is enough for that system. Especially if the cars get older.

If you've done a brake fluid change lately, has the problem appeared after that? So maybe something went wrong.

If you did a complete and proper break fluid change and there is still a problem you should check the master and slave brake cylinder. If you have a MT with a clutch you should also check the slave cylinder on the clutch.

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Old 04-07-2015, 09:24 PM   #8
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Fluid is fine & haven't changed for a while.

Drains were blocked but not a lot of water in the battery compartment & it has been raining pretty heavy here for a few days.

Might just change out the bosster & hope for the best.

Quote:
Originally Posted by Smallblock454 View Post
Sounds like a defect master brake cylinder.

Some ideas:

Break fluid level is OK and brake fluid is new and the complete system was ventilated lately?

Do you have a MT? Was the line to the clutch slave cylinder also ventilated? If not, this sometimes causes strange effects.

Was the system ventilated correctly? Longest brake line to shortest?

Did you use a pressure system to ventilate the brake system? If you use too much pressure this can harm the ABS system. Also you can damage the fluid reservoir container. I think 1 bar is enough for that system. Especially if the cars get older.

If you've done a brake fluid change lately, has the problem appeared after that? So maybe something went wrong.

If you did a complete and proper break fluid change and there is still a problem you should check the master and slave brake cylinder. If you have a MT with a clutch you should also check the slave cylinder on the clutch.

Regards Markus
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Old 05-18-2015, 02:43 PM   #9
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Replaced the booster, bled the brakes. Front bled ok but rear wouldn't. Unable to get any fluid from the nipple. Took it for a test run & only front brakes worked & then stuck on. Will need a tow to get it home
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Old 05-18-2015, 05:34 PM   #10
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Ok, got it home & up on stands.

When I open any of the 4 bleeder nipples on the rear the pedal stays hard & won't push any fluid out.

Any suggestions?
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Old 05-18-2015, 06:00 PM   #11
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So like in the parking lot speeds when attempting to maintain low speed with the brake pedal it drops right?

brake master...

cups in master are bypassing fluid but if you hit it hard the pedal is stiff...slow and soft, the cups bypass fluid

Last edited by healthservices; 05-18-2015 at 06:02 PM.
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Old 05-18-2015, 07:12 PM   #12
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So like in the parking lot speeds when attempting to maintain low speed with the brake pedal it drops right?

brake master...

cups in master are bypassing fluid but if you hit it hard the pedal is stiff...slow and soft, the cups bypass fluid
Nope. Neither of those. Pedal is hard & stay hard.

Seems like the rear is blocked so maybe an ABS issue.

Can you bleed the ABS?

Had a look at it & no nipple so not sure.

I do not have traction control so no duramatic required as far as I can tell from reading the forums.
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Old 05-18-2015, 08:02 PM   #13
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Sorry i missread tour first post. Almost sounds like an older style proportioning valve stuck rearward but I thought they did away with those. Do they have them on the boxsters?
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Old 05-27-2015, 04:03 PM   #14
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Brake problem

I am still having the same issue. Haven't had a chance to look at it further.

Any idea's fellow Boxsterers?
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Old 09-18-2015, 02:35 AM   #15
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I am still having the same issue. Haven't had a chance to look at it further.

Any idea's fellow Boxsterers?
Got myself a Durametric but is unable to scan ABS so am back where I started.

Anyone got any idea's on where I can find out how to resolve this issue?
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Old 09-18-2015, 05:04 AM   #16
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Look at the rear rubber flex or (any other flex hose for that matter) hoses, they can collapse inside and block the flow. I have had this happen on an Alfa Romeo in the past.
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Old 04-11-2016, 05:37 PM   #17
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Update

Have been away & not looked at the car for a while.

Anyone have any new idea's?
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