# Cant get brakes bled!!?????



## csixer (May 18, 2012)

I replaced the right front caliper on my hb. I cannot for the life of me get these brakes bled out. I have been a heavy truck mechanic for 15 years. Im no stranger to working on vehicles. I know very well how to bleed brakes correctly. I have tried everything! I have tried gravity bleeding, standard 6 or 7 times, removed MC and bench bled and reinstalled and bled at lines, jacked front of truck up and rear of truck up, i have no leaks and fluid is coming out of bleeders. But pedal goes right to the floor when you take foot of brake and put it back on its to the floor, i cannot get it. I just used a vaccum pump and went through 4 MC's worth of fluid and still the same....im totaly stumped....


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## Grug (Aug 20, 2009)

Hey there, csixer. Welcome!

Well, I'm not trying to insult you, but is it possible the caliper is for the wrong wheel (side)? I know that the calipers will fit either side, but if the bleeder nipple is below the point where the brake line threads in (as opposed to above) then the brakes won't bleed out. Make sense?

I discovered this the hard way when I installed the calipers on the wrong wheels (got 'em reversed). I bled, bled and bled...but nothing worked. Switched 'em back and the brakes bled out almost immediately.


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## rogoman (Dec 16, 2004)

If you have an LSV and/or ABS, they they need to be bled also.


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## csixer (May 18, 2012)

I do not have abs...and what is an lsv? If its the valve on the pass side firewall its been bled 100 times also.... And yes the caliper deal was actualy a good thing for me to check thanks you.... But unfortunatly it is the right one and the bleeder is at te top. Thank you for the tip. But just tried again through 3 mor master culinders full of fluid and te pedal will pump up n get stiff then the next time you go to pump... To the floor it goes


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## Grug (Aug 20, 2009)

The LSV (load sensing valve) has something to do with distributing braking force between the front and rear wheels based on how much cargo you're carrying (I think).

On your truck, it's probably mounted on the rear axle (passenger side, I think). You'll see it as it has lines going into it and there's a nipple on it. 

The only thing that seems odd to me is that if you only replaced a caliper and then went to bleed the brakes, you can usually get them bled without having to touch the LSV (unless of course the fluid in the master got too low and air was pulled into the system).

On my old '93, I did brake work over the years (replaced lines, calipers, wheel cylinders...) and not once did I ever bleed the LSV. Always got good pedal by just bleeding the wheels. I know, I know...that's not what the FSM says.

But at this stage, I'd take Rogo's advice and bleed out the LSV as there could be an air pocket trapped in there. 

BTW, LSV's are very expensive! So be careful with it.

Good luck, man!


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## smj999smj (Jan 1, 2006)

You shouldn't have to mess with the LSV if you're working only on the front brakes.


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## Grug (Aug 20, 2009)

Yeah, I initially thought that the LSV shouldn't factor into it. But he mentioned in his initial post that he'd removed the MC. So it's possible that air has somehow gotten into the system and been trapped.

I've had calipers off before and only bled the front brakes...with great pedal results.

I'm starting to think maybe one of the rubber lines up front might have collapsed on the inside. Although I suppose if there's good fluid coming off the caliper when it's bled, then the rubber line is probably ok.

If you had good breaks before the caliper was removed and now you don't, it's got to be something relatively simple (annoying, but simple).


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## zanegrey (Dec 5, 2005)

EXTEND THE BRAKE BOOSTER ROD OFF THE BRAKE PEDAL .. YOU DO NOT HAVE ENOUGH THROW...


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## smj999smj (Jan 1, 2006)

zanegrey said:


> EXTEND THE BRAKE BOOSTER ROD OFF THE BRAKE PEDAL .. YOU DO NOT HAVE ENOUGH THROW...


But the question would be: "If he only replaced a brake caliper, why would the pushrod throw be affected?" 

Did you follow the FSM procedure? Nissan recommends putting a 2" block under the brake pedal to prevent "full-stroking" the pedal while bleeding, which could damage the master cylinder. Nissan recommends bleeding using the following order:

1) Load Sensing Valve air bleeder (LSV) if equipped.
2) Left rear.
3) Right rear.
4) Left front.
5) Right front.

WARNING: Do not bleed the brakes with the drums removed. The wheel cylinders will over-extend and eject the pistons.


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## LvR. (May 26, 2010)

IMO the "going to the floor" bit is the answer ...............(as per smj999smj's and the FSM's warning)

The MC will develop a smooth area where the piston "normally" traveled in the past - the rest of the MC cylinder inside will get covered in muck and rust/pits. Given enough time you eventually have a MC that you actually don't want to stroke fully (or then beyond its normal stroked life) for fear of damaging the rubber seals on the piston and also fear of dislodging muck that could get trapped in one of the plate valves in the MC piston assembly.

I will bet that you have a damaged MC seal or valve assembly given your efforts described here

Easy enough to prove - block off all outlets on the MC (make plugs if you don't have) - bleed the MC and see if you still have this "going to the floor" characteristic - if you do you know the solution.


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## Grug (Aug 20, 2009)

Hey there, csixer...are you still out there? Any updates?

This is developing into one of those thread where I'm startin' to get real curious as to what the problem is (or hopefully...was).


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## Twistedfaith13 (Mar 11, 2015)

Im rather curious as well im having a similar issue with my 93. new MC bled properly. all new lines going to the back and cant seem to get the pedal to harden. gets hard with truck off after double pumping but once started i have to pressure there. brakes dont kick in until its almost to the floor


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## smj999smj (Jan 1, 2006)

Make sure the rear brakes are adjusted properly.


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## zanegrey (Dec 5, 2005)

you do not have the mc rod in the correct position


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## zanegrey (Dec 5, 2005)

you do not have the m rod in the correct position..


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## Minitrucker73 (May 18, 2016)

zanegrey said:


> you do not have the m rod in the correct position..


How is that possible? It only goes in one way?
I just replaced two lines that head to the rear of my 97 & the master cylinder. I can't get pedal either, I've bled the brakes til I'm blue in the face...no pedal!
Haven't bled the proportioning valve though, didn't know you could.

And you know what else I noticed? When depressing the brake pedal, fluid shoots straight up inside the firewall side of the fluid resivoir


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## zanegrey (Dec 5, 2005)

WHT I MEANT BY YOU DO NOT HAVE THE RODIN THE CORRECT POSITION IS ..

IT IS ADJUSTABLE FROM THE PEDAL SIDE EVEN A MM CAN MAKE A DIFFERENCE...


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## Minitrucker73 (May 18, 2016)

Thanks, any thoughts on my situation. My pedal was fine before I replaced the two lines running to the rear. And I'm pretty sure I just
Wasted my $$ on a new master cylinder.


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## zanegrey (Dec 5, 2005)

FIND A WAY TO GET A HOSE ON THE BOTTLE OF BRAKE FLUID AND GET IT HOOKED TO THE PPV BLEEDER NIPPLE.OPEN THE PPV BLEEDER.
THEN GO TO THE FARTHEST AWAY BLEEDER AND START THE BLEEDING PROCESS.

AS HARD AS IT IS TO IMAGINE .. THERE HAS TO BE AIR IN THE LINE..

ALSO ANY TIME YOU PUT ON NEW MC THAT ROD HAS TO BE ADJUSTED..


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## jorge_jeb (Oct 14, 2016)

hello hope someone help me.

i was having trouble with bleeding too. the info on this thread was very helpful. while doing the bleeding i realize one of my calipers has the bleeder downwards and the other is in the correct way so i have to do some stuff to get the caliper bleed. the issue is that i have two calipers from the same wheel (passenger side this case) and im having some braking trouble the truck goes side when braking (goes passenger side). does caliper issue is related with my problem?

sorry for the bad english, hope u understand my problem.


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## zanegrey (Dec 5, 2005)

I AM NOT SURE WHAT YOU ARE ASKING..

BUT IF YOU ARE NOT GETTING PEDAL AFTER INSTALLING A CALIPER IT IS AIR IN THE LINES ..


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## rogoman (Dec 16, 2004)

jorge_jeb said:


> hello hope someone help me.
> 
> i was having trouble with bleeding too. the info on this thread was very helpful. while doing the bleeding i realize one of my calipers has the bleeder downwards and the other is in the correct way so i have to do some stuff to get the caliper bleed. the issue is that i have two calipers from the same wheel (passenger side this case) and im having some braking trouble the truck goes side when braking (goes passenger side). does caliper issue is related with my problem?
> 
> sorry for the bad english, hope u understand my problem.


If the caliper bleeder is pointing down, then you will never be able to properly bleed that cylinder and line if there's air present.


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## rogoman (Dec 16, 2004)

Minitrucker73 said:


> How is that possible? It only goes in one way?
> I just replaced two lines that head to the rear of my 97 & the master cylinder. I can't get pedal either, I've bled the brakes til I'm blue in the face...no pedal!
> Haven't bled the proportioning valve though, didn't know you could.
> 
> And you know what else I noticed? When depressing the brake pedal, fluid shoots straight up inside the firewall side of the fluid resivoir


If you've got fluid shooting up to the outside, then everytime you release the brake pedal, air will be introduced back into the system. Fix that leak!


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## jorge_jeb (Oct 14, 2016)

forgot.

i replace master cylinder, new front pads, new disc driver side, rear brakes were adjusted..

i mean my problem is that the truck is pulling passenger side when braking


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## jorge_jeb (Oct 14, 2016)

the way i bleed the drivers caliper. put the caliper and pads on the old disc next to the brake line and put upwards the bleeder, the was the only way when i finally have braking. i think the damage disc was making the issue but after replacing it the problem follows. 

my other question, both bleeders have to be upwards? in my understand the caliper with the bleeder downwards was changed for some reason? i want to make sure of that for starting from replacing that caliper


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## rogoman (Dec 16, 2004)

csixer said:


> I replaced the right front caliper on my hb. I cannot for the life of me get these brakes bled out. I have been a heavy truck mechanic for 15 years. Im no stranger to working on vehicles. I know very well how to bleed brakes correctly. I have tried everything! I have tried gravity bleeding, standard 6 or 7 times, removed MC and bench bled and reinstalled and bled at lines, jacked front of truck up and rear of truck up, i have no leaks and fluid is coming out of bleeders. But pedal goes right to the floor when you take foot of brake and put it back on its to the floor, i cannot get it. I just used a vaccum pump and went through 4 MC's worth of fluid and still the same....im totaly stumped....


If you thoroughly bled the system properly, then inspect the brake booster by going through the test procedure that's spelled out in the FSM; a bad brake booster can cause a dropping brake pedal; also make sure the brake booster output rod length is correct as specified in the FSM. Check all the brake hoses to make sure they are in good condition; no cracks.


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## Shadetree68 (Oct 26, 2016)

*1995 HB bleeding issues*

I have a 1995 Nissan Hard Body Pickup, 2wd extended cab, 6 cyl. I am also having issues bleeding the lines after replacing blown brake lines to the rear of the truck. I have no leaks, I have run 2 qts of fluid through the master. I can pump the brakes up, then nothing. I am getting a steady stream of fluid, with no air at the wheel bleeders. I also bled the unit under the passenger side in front of the gas tank. Any help would be greatly appreciated.


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## Shadetree68 (Oct 26, 2016)

I got under the truck looking for other bleeder valves. I found a bleeder on top of the LSV. (Mine was above the rear axel and had 3 brake lines attached). I bled the valve and had full brakes in less than a minute.


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