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Discussion Starter #1
Had a scare yesterday when my Mo's brakes significantly failed unexpectedly.
I was just reaching a stop sign and ran over a small pothole. As I pressed the brake pedal the car slowed down, but it would not stop. Had the pedal all the way to the floor and it didn't come to a complete stop until about 6-7 feet beyond the stop sign. Scary...

It kept on happening for the remainder of the drive. I parked and turned off the car, and inspected the brakes and tires. I didn't see anything and started it up again - strange thing, now its like nothing happened and brakes are fine! Brought it to Nissan service, they didn't see anything wrong. He suspected it was an electrical glitch and restarting had reset it.

Anybody had anything like this happen before?

2009, just reached 71,000 miles. Never had problems with the brakes (except for that incessant squealing!!). Oh, had the squealing since day one (March 2008), brought it to the dealer twice and they never figured it out, or heard it, of course.
 

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Not sure about the brakes not working...maybe something splashed up onto the rotors that eventually burned off. Was the pedal still as firm as normal or did it go to the floor or lower than normal? If so, we know it is fluid system issue and most likely brake booster is my guess. If not, at a loss for why all brakes would lose stopping power and then return.

As far as squeal, had same on my mo when new. Dealer said it was normal movement. I said bs and took brake pads off my self. No anti squeal or shims on them (from the factory this way). I replaced with Akebono ceramic pads and liberal coating of anti squeal on backs and not peep in 40k.
 

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I'd go straight to the power boost unit. If you had a broken brake line the level of the brake fluid wouldd have dropped and two of the four brakes would still work, but that would not improve afterwards.

Most brake boost units are vacuum powered; there's a check valve in the vacuum line that holds the vacuum so that it's available for the boost process. A vacuum line that is worn and might leak or a check valve that gets stuck could easily cause the problem you describe. Of the two, I'd guess check valve because it could get jammed and then free up. A hose would tend to keep leaking.

Take that dang thing in for another check on the brake booster, vacuum lines and check valve immediately. If it happened once, it could easily happen again in tight traffic.

I didn't check the manual so this is all "best guess" stuff. For all I know the brake booster is run by a tiny Latvian dwarf who took a day off from supervising the brakes......>:D
 

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Pilgrim;481553 said:
……..a tiny Latvian dwarf who took a day off from supervising the brakes......>:D
Aren't we being a little insensitive to Latvians here? Not just a Latvian dwarf, but a TINY one at that! :laugh:

Take care!

Jim
 

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I shall alert the LDADL (Latvian Dwarf Anti-defamation league)....if I find them.
 

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Discussion Starter #6
Not sure about the brakes not working...maybe something splashed up onto the rotors that eventually burned off. Was the pedal still as firm as normal or did it go to the floor or lower than normal? If so, we know it is fluid system issue and most likely brake booster is my guess. If not, at a loss for why all brakes would lose stopping power and then return.
The pedal was still firm as normal, just nothing was happening. Yes, very odd (but thankful) that they came back to normal. I think the service guy thought I was smoking something... Going to take to another dealer and see if they can figure it out - while mentioning all the posted possibilities (but not the strange Latvian references???). Thank you all!
 

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I'd go straight to the power boost unit. If you had a broken brake line the level of the brake fluid wouldd have dropped and two of the four brakes would still work, but that would not improve afterwards.

Most brake boost units are vacuum powered; there's a check valve in the vacuum line that holds the vacuum so that it's available for the boost process. A vacuum line that is worn and might leak or a check valve that gets stuck could easily cause the problem you describe. Of the two, I'd guess check valve because it could get jammed and then free up. A hose would tend to keep leaking.

Take that dang thing in for another check on the brake booster, vacuum lines and check valve immediately. If it happened once, it could easily happen again in tight traffic.

I didn't check the manual so this is all "best guess" stuff. For all I know the brake booster is run by a tiny Latvian dwarf who took a day off from supervising the brakes......>:D
^ This is all good stuff except this part.. "and two of the four brakes would still work". Go open a single bleeder valve and see how well your brakes work. As soon as you introduce a leak in the system none of the brakes work because the hydraulic fluid will take the path of least resistance. That's why cars are required to have a mechanical "emergency brake" that operates outside of the hydraulic system.

But yes, if it was a leak it wouldn't have come back on it's own. I originally thought ABS because I've had the ABS engage more that it should when stopping over bad potholes, but that would have stopped being an issue as soon as you were off the pothole.
 

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Thanks, Jay...good notes.

Starting about 1980 with the Chevy Citation, many manufacturers changed their braking circuit design so that there were two circuits, each having one front and one rear tire. The idea was that if one of them broke (bad brake line ferinstance) the other circuit would still operate. Usually those would be set up something like LF and RR on one, RF and LR on the other, so that if one of them failed the remaining circuit would be able to stop the car in a straight line by operating on both sides of the car.

I'm not sure how the Murano is set up, but I have always thought that's a good concept. I haven't tried opening a bleeder, but you may well be right.

This was more an excursion into theory than experience on my part.

The check valve seems like a good candidate to me.
 

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Every car I have ever bled brakes on (and that's every on I've owned as well as several belonging to friends) the pedal goes right to the floor when a single bleeder is opened up.
 

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My guess it that the pothole may have triggered the anti-lock breaks for a split second, and then you slammed on the break pedal, perhaps while it was trying the anti-lock thing. Maybe it turned on and off really fast, but your manual breaking caught it in the middle, and it sort of froze mid anti-lock?? Basically, the pothole caused a glitch in the matrix, and restarting the vehicle reset everything back to normal. That's what I think happened. :)
 

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Had to be an ABS issue, probably brought on by the pothole. Other than the ABS, your brakes are hydrolic, not electric and nothing to reset. So if your pedal was firm, it's not a fluid leak issue. I wouldn't worry if you had the dealer check them out. if it should happen again (and I'venever heard of such issues on a Murano) remember you always have your E brake as a last resort while going slow.
 

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Every car I have ever bled brakes on (and that's every on I've owned as well as several belonging to friends) the pedal goes right to the floor when a single bleeder is opened up.
True. I may have to pause for a beer and deep philosophical reflection. :nerd:
 
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