Brake problems

[Tweaked]

Alright, I think this may be my first post so hello.

 

I've got a 92 Pathfinder with 4 wheel disc brakes and rear ABS I have seen in my searches something about LSV but I don't beleive I have that option as I can't see it anywhere on the passenger side frame rail all I see is the ABS valve. When I first got the truck (free from in-laws) the brakes were dragging so I put on a set of old calipers a freind gave me...we weren't sure if they still worked but it was worth a shot. After putting them on I bled the front brakes and had pretty much no damn pedal. So we bled the entire system, still nothing. So I put the old calipers on just to make sure I could get pressure again...nothing. So I replaced the master cylinder....bled it and the entire system...still no brake pressure so last week I went out and bought two brand new calipers, bled the system and still no damned pressure.

 

I'm thinking its somehow the booster as when the truck is off when I pump the pedal it builds a little pressure but if I leave it for 30 secs it looses all of it and when I start the truck the idle goes wonky if I keep pumping the brakes and it will build very little pressure and then if I'm off the pedal for even a couple seconds it will go right to the floor. Also I sprayed some water right where the master and the booster meet up and if I have someone pumping the brakes I can see it bubbling like air is being pushed out.

 

So am I right do I have a bad brake booster?

 

...oh and I did inspect the check valve going to the booster it is only allowing air one way.

Edited October 15, 2007 by Tweaked

[denisb]

According to manual (since I've never bled ABS). Disconnect ground and actuator connector from ABS unit with ignition off.

 

Then bleed in the following order.

 

1 load sensing valve (if equipped)

2 left rear

3 right rear

4 left front

5 right front

6 Rear ABS Actuator

 

The rest is normal bleeding. If you went thru those steps and still have problem......then someone else needds to pipe in since I am not sure.

[Tweaked]

Well I disconnected the battery but i didn't pull anything off of the ABS unit.

[Tweaked]

Alright so I replaced the Booster and still have the same damned problem. I think this truck is going to the scrap yard unless someone can tell me what the hell the problem is.

[GhostPath]

Alright so I replaced the Booster and still have the same damned problem. I think this truck is going to the scrap yard unless someone can tell me what the hell the problem is.

 

Um, have you replaced the master cylinder yet?

[5523Pathfinder]

Ok, so you bled the entire system. Did you remove the rear drums and inspect the wheel cylinders and verify they are not leaking? When you bled the brakes, did you make sure there was no air coming out the bleeders. Make sure you start in the right rear (as if you were sitting in the drivers seat). It sound like air in the system or a leak. Double check all of the obvious and make sure you didnt miss anything. Oh, is the pedal stiff when you push on it after bleeding without the engine running? And last idea, did you verify vacuum to the booster? Check those and get back.

 

When I have to bleed brakes when I am not at work, I use a piece of hose and put it into a clean, clear plasitc bottle and fill it with brake fluid so the hose end is submerged. When you bleed the brakes, you can watch the fluid and air go into the bottle. It also helps to keep air from going back in.

Edited October 16, 2007 by 5523Pathfinder

[5523Pathfinder]

So I put the old calipers on just to make sure I could get pressure again...nothing. So I replaced the master cylinder....bled it and the entire system...still no brake pressure so last week I went out and bought two brand new calipers, bled the system and still no damned pressure.

 

Looks like he did....as well as some other parts

[Tweaked]

Um, have you replaced the master cylinder yet?

 

The irony here is that your trying to make me look stupid with your comment but had you read the 1st paragraph of the 1st post you would have saved you, yourself looking foolish.

 

But thanks for the smartass comment.

[Tweaked]

Ok, so you bled the entire system. Did you remove the rear drums and inspect the wheel cylinders and verify they are not leaking? When you bled the brakes, did you make sure there was no air coming out the bleeders. Make sure you start in the right rear (as if you were sitting in the drivers seat). It sound like air in the system or a leak. Double check all of the obvious and make sure you didnt miss anything. Oh, is the pedal stiff when you push on it after bleeding without the engine running? And last idea, did you verify vacuum to the booster? Check those and get back.

 

When I have to bleed brakes when I am not at work, I use a piece of hose and put it into a clean, clear plasitc bottle and fill it with brake fluid so the hose end is submerged. When you bleed the brakes, you can watch the fluid and air go into the bottle. It also helps to keep air from going back in.

 

Yeah I bled the entire system (in the following order)

 

The ABS valve on the passenger side framerail

Rear pass side

Rear drivers side

Front pass side

Front drivers side

and then bled the ABS valve again. ( I bled it first because I had bled the system a couple times before this without realizing the ABS valve was there, so I did it once first and once afterwards) I did bleed it untill I saw no air comming out and I used one of those bleeder systems with a tube going into a bottle. No air bubbles. I haven't checked the rear but they are not drums they are discs

 

The peddle will stiffen up a bit when you pump it with the engine off but if you wait a couple seconds it looses the pressure and you can push the pedal to the floor again. The thing that is frustrating is that none of this was happening untill I changed the front calipers, there was plenty of pedal pressure but the calipers were dragging. As soon as I replaced them there has been no pressure since.

[GhostPath]

The irony here is that your trying to make me look stupid with your comment but had you read the 1st paragraph of the 1st post you would have saved you, yourself looking foolish.

 

But thanks for the smartass comment.

 

 

Well, given the long run-on sentences that you use, who can be blamed for just skimming it instead of trying to read the whole thing and falling asleep in the process?

 

Did you properly bench bleed the master cylinder before installation?

[Tweaked]

Well, given the long run-on sentences that you use, who can be blamed for just skimming it instead of trying to read the whole thing and falling asleep in the process?

 

Did you properly bench bleed the master cylinder before installation?

 

My god, I'm not going to argue semantics with you.

 

Yes I bench bled the master cylinder before it was installed, it seems like air in the lines to me but I'll be damned if I can find where. That and the flippin ABS light is on and has been since after I started this process.

[5523Pathfinder]

Easy Fellas, no big deal. We are just trying to help each other out. Fixing anything over the net is a little tough.

 

Anyways, Tweaked, how much brake fluid have you used so far with all of the bleeding? Definatly sounds like air still. It may take a while manually bleeding to get the air out. I wouldnt even piss with the ABS bleeders. Just bleed at the wheels.

Edited October 16, 2007 by 5523Pathfinder

[denisb]

You mention replacing your calipers with another set (not being sure they were good) and then going back to your old set. Let's say for arguments sake both set were seized, you would not be able to bleed properly and you would probably see a mushy if not no existent pedal. Make sure none of your pins (front or rear calipers) are seized.

 

Also I had one of my rear lines go bad once and had to take my master cylinder appart (seals and all), reasemble and then it bench bled perfect. Not sure if my bypass valve had seized when the line broke, but I could not get a good peddal before and when I re-bled the master and then re-bled the brakes everything panned out.....maybe just weird gremlins....

[Tweaked]

Easy Fellas, no big deal. We are just trying to help each other out. Fixing anything over the net is a little tough.

 

Anyways, Tweaked, how much brake fluid have you used so far with all of the bleeding? Definatly sounds like air still. It may take a while manually bleeding to get the air out. I wouldnt even piss with the ABS bleeders. Just bleed at the wheels.

 

Putting a measurment on the amount of brake fluid is hard but I've gone through probably about 4 or 5 master cylinders reseviors worth (but don't worry I never let it run below the min mark on the resevior) You say ABS 'bleeders' is there more than one becuase all I could see was one bleeder valve that stuck out towards the middle of the vehicle. I really don't see any more air comming out though, I've bled plenty of brakes before. I've got 3 other vehicles (Probe GT, Mazda MX6, and an F-150) and have never had this kind of issue before with brake work.

 

Very frustrating.

[Tweaked]

You mention replacing your calipers with another set (not being sure they were good) and then going back to your old set. Let's say for arguments sake both set were seized, you would not be able to bleed properly and you would probably see a mushy if not no existent pedal. Make sure none of your pins (front or rear calipers) are seized.

 

Also I had one of my rear lines go bad once and had to take my master cylinder appart (seals and all), reasemble and then it bench bled perfect. Not sure if my bypass valve had seized when the line broke, but I could not get a good peddal before and when I re-bled the master and then re-bled the brakes everything panned out.....maybe just weird gremlins....

 

I've got brand new caliper on right now (both fronts) I traced the lines from the master cylinder to all 4 corners and they are all dry from what I can see so I'm fairly certain it's not a cracked line. I suppose I could go ahead and re-bleed the master again for the hell of it and see what happens.

[ASMBLYLINE]

I've got brand new caliper on right now (both fronts) I traced the lines from the master cylinder to all 4 corners and they are all dry from what I can see so I'm fairly certain it's not a cracked line. I suppose I could go ahead and re-bleed the master again for the hell of it and see what happens.

 

OK so im new here but not new to Pathys. I have a 95 and I ran into this same exact problem this week and i was going nuts trying to figure this out. I've been on every forum and checked every page on the net and this is the only place i could find another with the same problem. I was frustrated to find this post was never resolved! So I am going to resolve it for others who use the search feature.

 

Ok so same thing i had a stuck caliper and as soon as i replaced it i lost my pedal and never got it back. Bled a google times, Master cylinder, Bled some more, bashed my face against the garage floor, bled some more until i had enough and was almost defeated. Then my dumb ass finally found it. When replacing both calipers MAKE SURE the bleeder is at the TOP! If you put the passenger side on the drivers side the bleeder will be on the bottom and you will never get the air out!

 

I hope this helps just one person out there.

[Precise1]

Hah!!

 

Nice, thanks for the explanation. It is so obvious, I can see it being overlooked...

 

B

[Gaby]

On 5/13/2010 at 9:08 PM, ASMBLYLINE said:

 

OK so im new here but not new to Pathys. I have a 95 and I ran into this same exact problem this week and i was going nuts trying to figure this out. I've been on every forum and checked every page on the net and this is the only place i could find another with the same problem. I was frustrated to find this post was never resolved! So I am going to resolve it for others who use the search feature.

 

Ok so same thing i had a stuck caliper and as soon as i replaced it i lost my pedal and never got it back. Bled a google times, Master cylinder, Bled some more, bashed my face against the garage floor, bled some more until i had enough and was almost defeated. Then my dumb ass finally found it. When replacing both calipers MAKE SURE the bleeder is at the TOP! If you put the passenger side on the drivers side the bleeder will be on the bottom and you will never get the air out!

 

I hope this helps just one person out there.

Im having the same issue, i replace Booster, Master Cylinder, both calipers front, metal lines and even hoses, bleed it a couple of times no pressure is staying. 
 

The last thing a mechanic visited me he told me it could a defective ABS also called Load Sensing Proportioning Valve (LSPV) by chat gpt 

 

Im not understanding are u saying to switch the calipers so the bleeder is below not on the top, becuase mines are in the top, but still no brakes.

 

My last hopes is the ABS bellow the passenger side of car outside connected to the brake lines, since it also has the ABS and BRAKE on the dash.

 

HELP I ALSO AM GOING CRQZY WITH THIS SITUATION.

[gamellott]

I suppose you can put the calipers on the wrong side when outright replacing them, which will put the bleeder screw on the bottom, which will not allow the air to escape when bleeding the brakes. I don't believe the ABS could cause an inability to bleed the brakes. If it's leaking, there would be obvious signs like a puddle somewhere... I haven't heard of such a thing ever happening.... I could easily be wrong though.

 

The Absolute best process I found to bleeding the brakes on these, is Gravity. Open the bleeder screw and let gravity do it's work. If you have a bubble in the system, it will pass. At least, that has been my experience. I've overhauled the rear calipers on mine several times because I can't seem to get the rust under control and they seize about once every other year. I think I may have found the holy grail and assembled them with silicone grease around the boot. So far, so good.

 

Another trick/process, Doorman makes these things called Speed Bleeders. Their documentation by application, I have found, is wrong though. IIRC, the documentation calls for a 33mm shaft and that is too short and will not seat. The 35mm shaft fits and seats properly. They're basically a check valve that allows the fluid to pass only one way when they're open. The process is simple, open the bleeder screw once installed, and pump the brakes a couple of times. Once done, shut the valve and check for leaks. You may have to clean the seat on the calipers since the seat on the Speed Bleeder is much larger than original and my have rust accumulated on the seat in the caliper.

 

Hope this might help some!!

[Slartibartfast]

I'm not sure what you mean by "no pressure is staying." Is it leaking somewhere? Squishy brakes? No brakes at all?

 

Did you adjust the rod from the booster so it goes the right depth into the master? Bench bleed the master?

 

Sounds like your calipers are the right way up. If they're installed with the bleeders down, then you won't be able to get the air out of the caliper, which was the cause of ASMBLYLINE's trouble. Fairly common mistake.

 

ABS is not a load sensing valve, and there is no load sensing valve on these. Chat GPT doesn't know crap. The ABS valve has a bleeder on it, have you bled there? An ABS unit with air in it, or a dump valve stuck open, could nerf the rear circuit, but the fronts should still work. The front brakes are not controlled by that ABS valve.

 

The ABS light means it's got an ABS code. There's a procedure in the service manual to jumper a couple pins in a plug under the dash and count the flickers, and that'll tell you what the ABS computer thinks is wrong. It may not be particularly helpful, but it's a place to start. BR section, download the manual from Nicoclub. It's a bit fiddly. I recommend recording the ABS light flickering with your phone so you can play it back and figure out what it's trying to tell you.

 

I had a hell of a time with my rear brakes several years ago. I bled it all kinds of ways and got nowhere. Then I blew out the rear line from the res to the rear flex line with compressed air and went down it with a pressure gauge, connecting it at each fitting, trying to find where I was losing pressure. I can only assume there was a gob of goo trapping an air bubble somewhere, and the compressed air got it, because I never found a problem, and it worked fine again afterwards.

Edited June 23 by Slartibartfast