Nissan Murano Forum banner
1 - 20 of 25 Posts

·
Registered
Joined
·
11 Posts
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.
 

·
Registered
Joined
·
808 Posts
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.
 

·
Administrator
Joined
·
9,358 Posts
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
 
  • Like
Reactions: mattski

·
The Phone Booth Fanatic
Joined
·
1,259 Posts
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
 
  • Like
Reactions: mattski

·
Administrator
Joined
·
9,358 Posts
I shall alert the LDADL (Latvian Dwarf Anti-defamation league)....if I find them.
 

·
Registered
Joined
·
11 Posts
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!
 

·
Registered
Joined
·
710 Posts
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.
 

·
Administrator
Joined
·
9,358 Posts
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 the opposite 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.
 

·
Registered
Joined
·
710 Posts
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.
 

·
Registered
Joined
·
196 Posts
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. :)
 

·
Registered
Joined
·
1,074 Posts
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.
 
  • Like
Reactions: suitcasejohnny

·
Administrator
Joined
·
9,358 Posts
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:
 

·
Registered
Joined
·
16 Posts
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
Murano brake problems, symptoms : brake pedal sinks to the floor, hit a bump/pot hole & you feel the brake pedal sink, etc. Exhaust smoking OR NOT.

Culprit: PCV valve going bad, dirty PCV valve (vacuum leak), Nissan brake design "horror ".

What to do...
My wife's 2011 murano had ALL of this & after replacing of the master brake cylinder (against my better judgment because it was NOT leaking brake fluid I found out that we was STILL in a dangerous situation when driving my wife's car --same problems still exist.

I removed the brake vacuum line for inspection & found my culprit! Vacuum check valve had low sealing capability to the point that whenever the car gets bumped the check valve looses it's sealing capability. I cleaned it (extremely thoroughly--i recommend replacement it comes integrated with the vacuum hose) & my problem went away.

So what causes this? After x amount of miles the PCV valve gets dirty with bypass gasses AND eventually OIL going into the VACUUM BALL CHECK VALVE that sits in a horizontal position on the booster vacuum line creating the vacuum leak and experiencing the problems above mentioned. The PCV valve should be replaced above 50-75k miles on the engine.

It only costs about $9.00 but with only 1 preventable wreck could cause you your life or of someone's. The loose of vacuum of the booster vacuum can occur with or without engine SMOKING out of the exhaust system--the point where the evident bad pcv valve. When the PVC goes bad the engine starts to SUCK a bit or alot of engine oil, leaking valve cover gasket, & the booster brake check valve not 8 seal all the time OR intermittently (when you hit a small or big bump on the road). Scary situation!

Change the PVC valve and you also could save the catalytic converter from getting contaminated with oil/ ruining (other expensive parts going bad that can be avoided.

On our murano this occurred in about 90,000 miles--but I now plan in changing the PCV valve every 50,000 miles.

I hope this helps anyone/everyone.

Btw--don't waste your $ on other things UNTIL you take care of this FIRST! I have read of people $pedinding thousands & still having the same problems..

The design of the intake manifold is set higher than the booster horizontal check valve which causes the vacuum leak--nissan really should redesign the location of the booster vacuum check valve & better training to the dealership techs.

I hope this helps
 

·
Administrator
Joined
·
9,358 Posts
Thanks for a complete and thoughtful post. That's the most thorough analysis of this situation that I have read. In most power braking systems, having the right vacuum level to the booster is indeed a critical part of the brake assist.
 

·
Registered
Joined
·
3 Posts
Murano brake problems, symptoms : brake pedal sinks to the floor, hit a bump/pot hole & you feel the brake pedal sink, etc. Exhaust smoking OR NOT.
Culprit: PCV valve going bad, dirty PCV valve (vacuum leak), Nissan brake design "horror ".
What to do...
My wife's 2011 murano had ALL of this & after replacing of the master brake cylinder (against my better judgment because it was NOT leaking brake fluid I found out that we was STILL in a dangerous situation when driving my wife's car --same problems still exist.
I removed the brake vacuum line for inspection & found my culprit! Vacuum check valve had low sealing capability to the point that whenever the car gets bumped the check valve looses it's sealing capability. I cleaned it (extremely thoroughly--i recommend replacement it comes integrated with the vacuum hose) & my problem went away.
So what causes this? After x amount of miles the PCV valve gets dirty with bypass gasses AND eventually OIL going into the VACUUM BALL CHECK VALVE that sits in a horizontal position on the booster vacuum line creating the vacuum leak and experiencing the problems above mentioned. The PCV valve should be replaced above 50-75k miles on the engine. It only costs about $9.00 but with only 1 preventable reck could cause you your life or of someone's. The loose of vacuum of the booster vacuum can occur with or without engine SMOKING out of the exhaust system--the point where the evident bad pcv valve. When the PVC goes bad the engine starts to SUCK a bit or alot of engine oil, leaking valve cover gasket, & the booster brake check valve not 8 seal all the time OR intermittently (when you hit a small or big bump on the road). Scary situation!
Change the PVC valve and you also could save the catalytic converter from getting contaminated with oil/ ruining (other expensive parts going bad that can be avoided.
On our murano this occurred in about 90,000 miles--but I now plan in changing the PCV valve every 50,000 miles.
I hope this helps anyone/everyone.
Btw--don't waste your $ on other things UNT you take care of this FIRST! I have read of people $pedinding thousands & still having thecsame problems..
The design of the intake manifold is set higher than the booster horizontal check valve which causes the vacuum leak--nissan really should redesign the location of the booster vacuum check valve & better training to the dealership techs.
I hope this helps
I'm posting to thank you for the info you have shared. 2011 Murano. Same no brake problem appeared after a large bump and then recovers to a perfect brake pedal without explanation. I replaced the PCV, easy enuf, took about an hour including the trip to the parts store. Hoping for no more of the magically disappearing brake pedal.
So far so good!
Cheers>
 

·
Registered
Joined
·
16 Posts
I'm posting to thank you for the info you have shared. 2011 Murano. Same no brake problem appeared after a large bump and then recovers to a perfect brake pedal without explanation. I replaced the PCV, easy enuf, took about an hour including the trip to the parts store. Hoping for no more of the magically disappearing brake pedal.
So far so good!
Cheers>
I aM glad it might help you. However, I want to apologize that after reading my suggestions I might not have been as clear as I could have been, as others have been with other's answers. And I want to be more on target:
The problem IS THE booster VACUUM CHECK VALVE loosing it's sealing capability in part, intermittently, or entirely by getting oil contamination caused by a "going bad" or bad PCV valve.
I would recommend replacing (or thoroughly cleaning both parts. Engine decreasing cleaning additive solvent, break cleaner (short length of time soaking) water clean out/drying in my case)) REPLACEMENT of both parts better/safer). In my case I cleaned & so far so good.
Again booster check valve and PCV valve NOT just one is the problem in this case of intermittently loosing break/pedal going/spongy/sinking break pedal!!!!
 

·
Registered
Joined
·
1,847 Posts
I'm skeptical that a bad PCV valve resulting in a vacuum leak caused this phenomenon. The complaint was that the brake pedal would sink to the floor after going over a bump/pothole, but a loss of vacuum to the brake booster would result in the opposite--a rock hard brake pedal. I suspect what these posters observed was some issue with the ABS system when they hit the pothole.
 

·
Registered
Joined
·
16 Posts
I'm skeptical that a bad PCV valve resulting in a vacuum leak caused this phenomenon. The complaint was that the brake pedal would sink to the floor after going over a bump/pothole, but a loss of vacuum to the brake booster w
I'm skeptical that a bad PCV valve resulting in a vacuum leak caused this phenomenon. The complaint was that the brake pedal would sink to the floor after going over a bump/pothole, but a loss of vacuum to the brake booster would result in the opposite--a rock hard brake pedal. I suspect what these posters observed was some issue with the ABS system when they hit the pothole.
"I need coffee" ...skeptical "...
This might have come up after my last answer, but recommend reading original post if you have time in addition.
In A nut shell: PCV valves go bad because of oil contamination (eventually so bad that you loose valve cover gasket as sealing capability ie. Oil leaks). Because of the location of the booster vacuum check valve (being at a lower location to the PCV, especially AFTER it going bad) it contaminates (oil/vapors,etc) the check valve's sealing capability going bad in part or entirely AFTER the oil contamination sitting inside the HORIZONTAL hose going to the booster. The sealing capability is lost! After "X" amount of time the oil inside the vacuum hose "bakes"/dries out causing the vacuum SEALING capability. Hence, depending upon the situation that you are at (miles) You WILL GET THE SYMPTOMS above mentioned--All or in part!!!!
Obviously, if you see oil seeping of the booster area than that's another thing (bad reserve...)
But YESSSSS. If you have brake pedal sinking, sinking pedal AFTER hitting a bump & you were on the brake pedal or hard break pedal feel/AND (or not) and then sinking pedal feeling --I would check the booster vacuum check valve. The (area--is dirty) caused by a bad or partial x PCV valve being defective. Again, keep in mind that this occurs AFTER "HIGH" mileage and TIME for the check valve to accumulate contaminates and then loose it's function occurs-- TO SEAL VACUUM!
In "my case" I have been going good for 1 year+/- AFTER cleaning BOTH of these items (but I recommend replacing both IF you want to be on the safe side. It is my wife's car and we have good insurance--LOL I am joking for the record!) AND have NOT experienced the problem since cleaning BOTH parts. It is NOT the ABS system. But yes, I have read that SOME dealers have gone that direction to then STILL have the same problem and both the dealer and owners giving up with frustration and ouf of $1,000.00s down the drain.
Stick to the basics FIRST!
I hope this helps someone and in clearing up a bit on this. I might not be good at writing technical. But stopping and thinking of in analogical way of how it works (brake systems) WILL help greatly. It had me for a while. But reading, analyzing what others posted got me "successfully" resolving this issue. Best of luck
 

·
Registered
Joined
·
1,847 Posts
I interpreted the OP's initial post that he had the brake pedal "all the way to the floor" to mean that literally, which suggests hydraulic failure, but I see that the OP clarified this in a later post that he meant this metaphorically and that he was actually pushing the brake pedal with great force with no loss of firmness and yet the car had great difficulty slowing down. Thus, I stand corrected on that front as what the OP experienced is indicative of a loss in vacuum brake assist.

Now, can contamination into the brake booster due to a faulty PCV valve cause intermittent sticking of the check valve? I'd say that's possible although there should be evidence of this in the hose to the booster so an inspection of the inside of the hose for contamination should either confirm this possibility or rule it out.

I'm surprised that the dealership techs didn't catch that if it was the problem in his case since the symptom he described should lead them to a careful inspection of the brake booster--unfortunately, the OP never posted back as to what the final resolution was.
 
  • Like
Reactions: Pilgrim

·
Registered
Joined
·
16 Posts
I interpreted the OP's initial post that he had the brake pedal "all the way to the floor" to mean that literally, which suggests hydraulic failure, but I see that the OP clarified this in a later post that he meant this metaphorically and that he was actually pushing the brake pedal with great force with no loss of firmness and yet the car had great difficulty slowing down. Thus, I stand corrected on that front as what the OP experienced is indicative of a loss in vacuum brake assist.

Now, can contamination into the brake booster due to a faulty PCV valve cause intermittent sticking of the check valve? I'd say that's possible although there should be evidence of this in the hose to the booster so an inspection of the inside of the hose for contamination should either confirm this possibility or rule it out.

I'm surprised that the dealership techs didn't catch that if it was the problem in his case since the symptom he described should lead them to a careful inspection of the brake booster--unfortunately, the OP never posted back as to what the final resolution was.
You are correct, verification of the check valve/hose could be done (is what I did & how sure I was and after a year w/o any problems after cleaning). However, I am a DIY back yard mechanic. Do NOT expect a dealer or any shop to suggest to clean bc of liability issues (the reason I suggest replacing the part). Also, dealers, shops, etc charge by labor hours...
Weather it takes them 10 min or 3 hours they rightfully will charge what the book hour values.
On THIS specific issue I successfully resolved it by cleaning the booster hoses (I think if I recall the check valve is INSIDE the booster hose (TIP: You will see a LUMP on the hose that'sthe check valve) and not in two pieces where you can replace the check valve. Maybe that's why some dealers aren't aware of it...

Trust me it is NOT complicated, easy to do, and if you have engine degreaser/break cleaner/ soap and water on had already--costs nothing but time. This was the case for me.
Don't over complicate it bc it's that easy. Just bc the new cars have very complicated things on it, on this Murano it is a BASIC old fashioned item AND CHEAP if you do this FIRST.
GOOD LUCK
 
1 - 20 of 25 Posts
Top