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joshs gurl
New User
Feb 27, 2009, 10:20 AM
Post #1 of 8
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brake problems
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Plz help!! Front brakes seizing up after about 10 min of driving on a 1998 mercury tracer 2.0 ls. brakes return to normal after letting them cool off. Already replaced break hoses. And breaks do not return at all. Plz help And I already checkd 4. contaminated and defective brake linings. Oh and its not tha break booster. Its the front disc brakes not the rear drums
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Feb 27, 2009, 10:45 AM
Post #2 of 8
(2593 views)
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Re: brake problems
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Hang in there - this could be tricky.
Does the brake pedal have UNUSUALLY little travel before they start braking even from cool/before driven?
Just ONCE but had this problem with NEW master cylinder that wouldn't allow fluid back to the reservior and that's not likely to happen by surprise but was a new faulty part.
Need to consider that BOTH front wheels are doing this so both caliper being frozen is unlikely. Any common item that restricts return flow to master cylinder or a VERY short free play area of master cylinder could do this.
What may be happening is even without using the brakes much - simple engine heat and things warming up, wheel bearings and so forth the fluid expands and would normally return to master cylinder's reservoir but if it can't it CAN apply pressure on the brakes as if you were doing it on purpose. Cooling down the fluid shrinks and they would test fine driving anyone nuts to figure out.
Since you have new fluid hopefully in there from doing the hoses I suggest pushing back on a piston and see it it will at all. If difficult to push back try with the bleeder open a tad and that would indicate caliper itself is ok and the resistance is elsewhere. There is perhaps ABS items, the proportioning/combination valve (never saw one do this) and just line going back to master. If a common line is pinched for some reason that could be an issue.
Gotta find this, it will ruin the front brakes and leave you stranded never mind they may not stop very well when needed!
T
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cek
Anonymous Poster
cekiser@yahoo.com
Apr 5, 2009, 6:34 AM
Post #4 of 8
(2526 views)
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Re: brake problems
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Tom,
Reviewing this topic, I also had vacuum leak and replaced the booster and master cylinder. This is where my troubles began.
I have a 1994 Chevrolet Z-71. 5.7. I have changed the power booster and master cylinder twice along with the vacuum check valve, ensured all air is bled from the system, changed the front rotor and pads.
Current Problem: When pressing the brake to a quick stop, the pedal remains to the floor and will not release for some time (10 seconds). I sometimes have to turn off engine and the pedal returns to normal position. I contributed this to vacuum but since a new check valve came with each power booster, I am not sure. This system has an isolation dump valve with abs. Thanks for your input
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Apr 5, 2009, 7:13 AM
Post #5 of 8
(2519 views)
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Re: brake problems
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"Pedal remains on floor ~ 10 seconds"
Egad! Basics here - the master cyl and booster if they weren't hooked up (hydraulically) to anything would return the pedal on their own - normally. Maybe not instant but better than that. I'd recheck master and booster.
Thought: Any chance non brake fluid was ever introduced to this system? That would render rubber seal to a sticky bubble gum and be a major problem if that ever happened,
T
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cek
Anonymous Poster
cekiser@yahoo.com
Apr 5, 2009, 7:36 AM
Post #6 of 8
(2511 views)
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Re: brake problems
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I agree but this is the second master/booster. I even looked at adjustment to the piston rod but according to the manufacturers instructions, "pushing the brake pedal slightly, fluid should begin to flow in the reservoir and it did. Over 2-gallons of Dot 3 have been flushed through the system during this effort. Could the isolation dump valve have an influence on the function. I'd love to have a detailed diagram of the hydraulics
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Apr 5, 2009, 8:46 AM
Post #7 of 8
(2502 views)
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Re: brake problems
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I don't have the software with diagrams or any special bleeding procedures. You would do better to make a new thread on this exact vehicle in the subject line and expain the behavior again to get some more exposure on the topic,
T
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cek
Anonymous Poster
Apr 5, 2009, 8:57 AM
Post #8 of 8
(2497 views)
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Re: brake problems
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Thanks,
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Re: brake problems
. I didn't think about that. Thank you VERY much. I -think- ive got this now lol