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PsstComeHere
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Jan 3, 2008, 10:47 AM
Post #1 of 8
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locked brakes
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I have a 99 Nissan Altima I replaced the driver side brake caliper 5 days ago. Today when driving to work it appears the front brakes have locked up. The brake petal is rock hard there is no travel whatsoever. I have no idea what is causing this. Yes it is both front brakes. I replaced the passenger side a month or 2 ago with no problem. Any help would be appreciated.
Scott
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jan 3, 2008, 2:13 PM
Post #2 of 8
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Re: locked brakes
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Have had a master cylinder do that - was defective and did it right away though. Problem was pressure was not allowed to return. The flex hoses can do this unseen by looking but I've never heard of both at once!!
Try just cracking open a bleeder to fronts doing nothing else - just a bit and don't let air back in. If both front wheels free up then the lock is upstream from the caliper(s) themselves or if just that one frees up perhaps both hoses are doing this. If you can get them stuck again try the same trick at the master cylinder. Usually the line closest to the firewall is for the front brakes. If that frees up the brakes then I blame the master cylinder.
See what happens with that and then if no luck we have to consider something anti-lock (if equipped) or a proportioning valve.
Is there a flex hose (one) used somewhere other than the front wheels at each caliper for just the front brakes?
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Guest
Anonymous Poster
Jan 3, 2008, 4:07 PM
Post #3 of 8
(4499 views)
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Re: locked brakes
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I was able to free them up by doing just that. I opened the bleeder for each of the front calipers pumped the brake pedal a couple of times then closed them and could get halfway home(appox 4 miles) before they locked up again. Repeated bleeding them again and got it home but it just progresses to the point of locking up again. The master cylinder was replaced 4 mnts ago the brake booster was replaced 1 mnt ago. So you think it is the master cylinder?
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jan 3, 2008, 5:54 PM
Post #4 of 8
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Re: locked brakes
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Don't think the master cyl or booster - YET. I'll explain below what happened with just one in a lifetime on me.
You need to get these sticky/locked you called it and see what releases them from letting pressure out - one at a time or this will just be a parts toss/ hit or miss repair. Need to know if both release or not with just one being bled out some. If you want to toss parts go ahead and toss the flex hoses - they're old enough anyway if never done. Get some PB on the flare nut to hose area now as they can be a nightmare if any rust with line to nut.
This is what's happening to you: Pressure gets in the front system either from hitting the brake or from the expansion of heat in using the brakes or even engine heat on lines. Your brake pedal has a freeplay area up top that allows fluid to return to master cylinder and allow you to even push back a piston in a caliper and fluid would return to the master. If as a test you just had someone touch the brake pedal the pistons would not retract that way. Brake fluid is locked somewhere yet unknown to apply front brakes and the warmer they get the harder they lock as the fluid expands.
The flex hoses used can tear inside and become a one-way valve. It would be a first for two to do this at once but possible. That problem is not that uncommon one at a time.
With the recent master and booster replacement I'd like to know how they felt right away and is there a wild temperature difference now and then? That may factor in later as a possible clue.
Also - what was the complaint(s) that led you to replace those?
______________________________
Same issue was a defective part on me: 92 Cadillac CDV needed a new master cylinder with the usual complaint of a fading pedal. Easy job on a mint car overall. I test drove it before giving back to customer/friend who lived about 10 miles from my shop. Got a call as she went right home that the brakes were smoking (front) and she had to floor it to get up her driveway against the resistance! Whoa! I went right over after telling her not to drive the car. Sucker behaved fine right in front of me but you could smell that they had been hot. WTF! Drove it myself back to my shop using just the parking brake as to not heat up the hydraulic parts of brakes at all and it did it to me too. That new master cylinder was a day short of being recalled as the centering hole in the back of it was not drilled deep enough so that the brakes couldn't return fluid and just engine heat was enough to apply the brakes and as they got warmer the thing about locked the wheels which when cooled spun free again. That took a while to figure out and when I test drove again when I felt it doing this again I did loosen the master to booster nuts and it freed right up.
Note: That happened right away with just that part replaced so I wasn't looking for everything in the car to be wrong. That problem could not have lasted without showing up for as long as your problem did before you had trouble which is why I am not ready to blame the other new parts right now.
Sorry for the long book on this but you really need to nail down what this is. If you have a defective part like I did then you must try another brand part or the same defect could be there and really mess up the diagnosis.
________________________
You'll pin it down. Drive carefully if you need to test it out and take a look at the front brakes as they may have been damaged if the heat was excessive and anything else that may have cooked if it got super hot.
Let me/us know what you find,
T
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Guest
Anonymous Poster
Jan 3, 2008, 6:49 PM
Post #5 of 8
(4494 views)
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Re: locked brakes
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From the begining: The brakes started to go about 8 months ago. I bleed them which worked for about 2 weeks. Replace brake shoes and pads all around. That fixed it for about a month. Then they started to go again at which time I replaced the master cylinder with a remanufactered one. A month or two later the started to go again. I replaced the passenger side caliper due to a leak. Had to bleed the brakes very 2 weeks to keep the brakes good. For 2 months then replaced the power booster with one from a junkyard due to the lack of avaliblity of a remanufactured one in our area. 1 month later they started acting up again, The other caliper started to leak. Replaced the driver side caliper this past Saturday and all was fine brakes were great. Today they began to lock up and I had to keep bleeding them just to get it home.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jan 3, 2008, 7:16 PM
Post #6 of 8
(4491 views)
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Re: locked brakes
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TOTAL CONFUSION! What was wrong with the booster? When they lock up do you or did you bleed them both (fronts) before you checked again?
Are you using brake fluid? This bit with leaking calipers and all this could be engine oil in the brake fluid! Gotta know more friend. Please don't just say the brakes were going as that means nothing to me. Noise, shake, pull, scrape, loss of pedal feel etc.,
T
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Guest
Anonymous Poster
Jan 4, 2008, 4:07 AM
Post #7 of 8
(4489 views)
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Re: locked brakes
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Sorry, when I said brakes were going I meant that the pedal would go to the floor before we got any real stopping power. The pads, master cylinder, booster, were replaced in an effort to solve this problem. The calipers were replaced as they developed leaks, seals wore out. Not at the same time. The fliud was store bought fresh. As far as freeing them up, my main concern was getting the car home first. so I just opened both bleeders, pumped brakes a couple times. Closed the bleeders. Then they would stay free for a bit, everytime I used the brakes they would slowly lock up again. I repeated this one more time before I got it home. I have not had the oppertunity to do much else. Will do more detailed work this weekend.
Your help is emmensely appreciated.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jan 4, 2008, 5:23 AM
Post #8 of 8
(4486 views)
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Re: locked brakes
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Ok:Let me/us know what you find,
T
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