Nissan Pathfinder Brake problem

-
Drache

Drache

1971 Dodge Dart Swinger
Joined
May 10, 2011
Messages
1,895
Reaction score
128
Location
Williams Lake, BC, Canada
Ok this is stumping me AND my mechanics. Maybe someone cane come up with some new ideas.

Ok so the vehicle is a 2000 Nissan Pathfinder. Anyone who has owned one seems to know the brakes are a little softer than other vehicles.

So about two weeks ago the brakes started going softer and softer to the point that the brake pedal needed to go down to the floor before the brakes would start to work.

I checked the fluid myself, everything was fine, to the top. Even bled the brakes, no problems.

So I took it into my mechanics and at the end of the day (after making sure all my brake pads, rotors, drums, etc were fine) they told me that my master cylinder was probably acting up. They fired in a new one, bled the brakes, and took it for a test drive. Still had problems.

They tested the ABS sensor and it was bad. So they went and threw a new one in there. Took it for a test drive, still had brake problems.

What is happening is the brake is going right to the floor and then you have to let it off and press the brake again. The second time the brakes work like they should.

So they tried bleed the brakes again. Didn't help. They fired off a phone call to Nissan themselves. They said to try bleeding the brakes a different way. So they did. Still no help.

They checked all the flex lines on the brakes to make sure the lines were bulging anywhere. They were fine.

Checked all the brake cylinders. They were fine. Tried to tighten all the brakes. They were good.

They are literally stumped. The only thing he hasn't played with is what appears to be a "load sensing proportioning valve" or "load sensing valve". Now the mechanic isn't really sure exactly how this thing operates. He tried search online but couldn't really figure out how it mechanically works on a Nissan. And it's an enclosed unit so he can't really open it up to find out. It has two brake lines going in and one coming out.
 
Maybe loose front wheel bearings pushing pads way back. Have seen wheel cylinders suck air in through the seals. Stuck caliper guide pins can give a low pedal. Pressure bleeding and properly bleeding the abs with a scan tool can make a big difference. I doubt it is the height valve as it really only limits pressure.
 
A bad brake booster can give you a low pedal. Usually if you can pump up a good pedal it is air.
 
Tech857 said:
Maybe loose front wheel bearings pushing pads way back. Have seen wheel cylinders suck air in through the seals. Stuck caliper guide pins can give a low pedal. Pressure bleeding and properly bleeding the abs with a scan tool can make a big difference. I doubt it is the height valve as it really only limits pressure.
Click to expand...

Interesting.

Now I've dealt with brakes that had air in the lines. This feels different.

It is literally like there is NO brake fluid in the lines on the first pump (goes to the floor with no pressure) and then on the second the brakes work perfectly with full pressure.

There is no leaking of fluid and no air in the brake lines. They have been bled a lot. They were pressure bled.
 
I just went through this with my Pontiac Montana, 3 different shops looked at it. One was a GM dealer who swore they fixed it. They all vacuumed the brake lines and checked the entire system. I had replaced the MC, front rotors and pads, rear shoes and the flex lines and bled the entire system.. Nothing fixed it, and it was driving me nuts. I tried one more place, a brake repair shop. About 5 hours after I dropped it off I had it back again, it was perfect! They pressure bled the brake system. That is the first time I have heard of doing it that way. Good luck, maybe you can find a shop that uses that system.
I saw you're last post, they did try that. Good luck, and when you find the problem please post the solution.
 
Usually a soft then quick hard pedal means the pads and/or shoes aren't moving.

Clean the living hell out of everything and put brake silicone (like Sylglide) on everything that has to move.
 
The load sensing valve changes the brake bias front to rear when you add weight to the rear.
It senses the height of the rear.
I'm pretty sure they are only on the 4wd Nissan's.
Not sure if that would cause the trouble though.
 
Like was said, stuck sliders or pads will cause this. Nissans are know for this. If it has 4 piston calipers, the lower Pistons freeze up. Also try bleeding backwards with a non- painted squirt can, fill with brake fluid, pump in each bleeder screw and see if bubbles come up through resovoir.
 
pete9857 said:
Like was said, stuck sliders or pads will cause this. Nissans are know for this. If it has 4 piston calipers, the lower Pistons freeze up. Also try bleeding backwards with a non- painted squirt can, fill with brake fluid, pump in each bleeder screw and see if bubbles come up through resovoir.
Click to expand...

Done this many times on dirt bikes whn tney wont bleed properly air seams to find a wayof being trapped and wont bleed out with normal methods.
 
Please check the front wheel bearings. I once had a brand new Ford F450 at work with a very low brake pedal complaint 2 other mechanics looked at it and could not find out why. It turned out the factory had left out one of the front outer wheel bearings and when you stepped on the brake the rotor would move causing the low pedal. Jack up the front end and use a long pry bar ( about 3ft ) and check and see if the rotor moves. I think this truck has hub assembles on the front (ie non rebuildable)

Brian
 
It still sounds like it needs to be bled, using a different method. Also we have a saying in my shop....."Just because the part is new doesn't mean it isn't bad". Wish I had a dollar for every new part that was junk out of the box. Doesn't seem to matter how good a brand is, they all seem to have quality control problems.
Now back to the bleeding... there are several ways to bleed brakes. Power bleeding, bottle bleeding, reverse bleeding, gravity bleeding etc. Don't know what method he used but it sounds like time to try something else. Time to think out of the box.We have even had to jacke one end of the vehicle up as high as possible and let it set, then gentley tap the pedal and let it set again then bleed. This lets the air work its way to the highest spot in the system so it can be pushed out with the bleeding. Some systems just aren't designed right when it comes to repairs, but yet work ok in everyday applications.

Also, though this is hard to see, with the vehicle sitting level have some one push the pedal down once and hold it while someone else looks at the fluid level. If the level drops (slightly) then returns, the master is bypassing and bad. Fluid should drop and remain as the air is compressed and displaced with the pads/shoes moving. This is hard to see but is seeable.



this comes with 40+ years of import service experience and had to do things you wouldn't believe to repair these vehicles!
 
I just had this problem on a customers Accent. One rear wheel cylinder was frozen and so were the front pads. It had a brake job not that long ago and they never put grease on the front pads so they froze up. the shoes were almost new, but they never checked the wheel cylinders. were the originals, on a 2002.

40 years experience on everything!!! O:)O:)O:)O:)O:)O:)O:)O:)
 
Ok they can't work on it as much since they have full paying customers that come first. (I pay parts at shop cost and only 50% labor).

Seems the Anti-lock brake module or whatever it's called (the part they replaced) was faulty. When they unplug the anti-lock brake module, the brakes work fine.

So they are having a hard time tracking one down (last time they found a used one and it cost me $250).
 
"When they unplug the anti-lock brake module, the brakes work fine."

Why can't you just leave the abs module unplugged? You would have regular brakes like back in the day. It could also be your wheel cylinders sucking in air.
 
bluetrane said:
"When they unplug the anti-lock brake module, the brakes work fine."

Why can't you just leave the abs module unplugged? You would have regular brakes like back in the day. It could also be your wheel cylinders sucking in air.
Click to expand...

Legally they cannot release the vehicle to me without anti-lock brakes due to BC laws. If I get pulled over and inspected by the CVSE and found not to have them working, my vehicle would be removed from the road until fixed.
 
Have the shop show you how to unplug the ABS. That way you can do it yourself. If you get pulled over and checked you could always find the problem right there on the spot and just tell the inspector that you were fooling around with something around the plug and you must have unplugged it by mistake.
To me though it sounds like something as small as your rear brakes being way out of adjustment.
 
it really doesn't sound like abs to me, either. The only ways I can think of that an abs module would do this is if a check ball was stuck inside the hydraulic part of the module or a solenoid is stuck on. neither one of these problems would change if you unplugged the module. If I was you I would ask them to replace my rear cylinders and rebleed or do it yourself.
 
bluetrane said:
it really doesn't sound like abs to me, either. The only ways I can think of that an abs module would do this is if a check ball was stuck inside the hydraulic part of the module or a solenoid is stuck on. neither one of these problems would change if you unplugged the module.
Click to expand...

And yet when the ABS module is unplugged, the brakes no longer need a double pump to work.

bluetrane said:
If I was you I would ask them to replace my rear cylinders and rebleed or do it yourself.
Click to expand...

I was there when it was bled twice (It's been done 5 or 6 times, every time they try something new). It was done correctly. All the cylinders were tested and they are all working 100%. They've done the pump and hold method, vacuum method, pressure method, reverse method, etc.

This is my cousin's shop. They've been in business almost as long as I've been alive and they know what they are doing. They are not incompetent in the least.
 
Drache said:
This is my cousin's shop. They've been in business almost as long as I've been alive and they know what they are doing. They are not incompetent in the least.
Click to expand...

I don't believe anyone thinks they are.

But, you did come on here asking for advice. There are those with experience in a different direction.

Hell, I've been doing it for 25 years. I still run into problems and ain't afraid to admit it and ain't afraid to ask for advice, as long as the problem get's solved. And anyone who knows me knows that I ain't incompetent when it comes to twisting a wrench.
 
You must log in or register to reply here.
-

Back
Top