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BrianD

I'm NOT getting any brake PEDAL! What the...? What is the prolm?

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My problem started in another topic titled, "Brake Failure while Driving".

(Update - the small "slit" in the diaphragm inside the reservoir cap HAS to be there! I glued it closed thinking that might be the prolm until

I was bleeding the system - checked it for fluid and found the MC sucked the diaphragm right outta the filler cap and into the reservoir filler neck! so..it's gotta get air from somewhere right? or the fluid won't go down the lines.)

 

Wifey ran the system dry after a brake line ruptured. I replaced 2 lines into the Load Sensing Valve that come from the front of the truck into a brass "splitter " type fixture and another on the back axle to the RR wheel. The bleeder screw on the LSV is extremely corroded. I tried to get a wrench & vise grips on there before heating it but there's no room to work. (I've replaced a few lines on the front LH and RH sides and nvr bled this LSV before. I drove it for 1000's of miles - no prolm.)

 

I have..No leaks.. bled the system 4 - 5 times now ( up to 10 X each rear wheel) trying to a get a stiff brake pedal..no luk.

I took the master cylinder out, cleaned it, checked the rubber seals inside and bench tested/ bled it. It seemed good.

Removed the rubber tube from the brake booster and the whoosh of air told me it checks out good too.

Re-installed the original MC - bled the brakes again and reconnected the battery ground cable and started it. Pedal goes to the floor like there's no fluid in the system what so ever.

 

Got a new master cylinder - bench bled it - installed it - bled the system AGAIN and NO BRAKES.

AGAIN ..after starting it, the Pedal goes to the floor like there's no fluid in the system what so ever. WTF?

So far..the pedal never Ever got "hard" when bleeding..I just checked again now and it sinks slowly to the floor.

I'm lukn in the factory Service manual for answers but I suck at electrical.

WHAT IS WRONG HEEEEE? Come on! Really?

Anybody have this happen to them?

I think I SHUD get SOME kinda stiff pedal while pumping it up before bleeding YA?

I saw 7,800,000 other ppl looking asking the same type questions on line.

One guy even installed 3! different Master cylinders and 2! ABS modules with no luk. Nevr did see the final result.

Your help will much appreciated!

Thanx in advance.

 

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Did you bleed the front at all? If you ran it dry there could be air up there. Also the ABS module might need to be activated to bleed properly. Any chance you could drive it somewhere (safely) and get the antilock to come on so it is sitting in a different position? I've had to do that on a car before.

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Thanx - yes I bled all 4 corners multiple times. I have NO brakes but I suppose I cud try doon that on my dead end/ no exit street. cheers

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A friend of mine used to work with a mechanic said they had this happen B4..about 20yrs ago. He said, " When the system has gone dry it doesn't bleed like normal. If the reservoir empties you just start again but all bleeders need to be open at the same time and the reservoir topped up as it bleeds ". I Nvr heard of this B4 - I don't have time to work on it anymore today but I will try this when I get more clear rubber tubing and make some catch bottles...but I'm still open to suggestions. I forgot to add that I checked the 7.5 amp ABS fuse in the dash and it was also good.

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First, you are always supposed to top the reservoir off as you bleed, don't let it get below the low mark. Second, if the split in the rubber allowing outside air to get in, that is bad. Brake fluid will absorb moisture from the air and that will cause corrosion in the system. The fact that it sucked the diaphragm in tells me that the fluid was too low.

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Huh, I always thought the diaphragm design was a domestic thing. My WD21 doesn't have one. My understanding is that the diaphragm is supposed to flex and follow the surface of the fluid, allowing air to come and go above it as the fluid level rises and drops below but keeping the two separate. Probably worth replacing at some point but I doubt it's what's screwing up your bleed.

 

You might get lucky with a gravity bleed but I suspect the LSV's got an air pocket in it that will only come out through the bleeder. It makes sense that you didn't have to bleed it when you did the front lines--air would have to go a long way to get from the front brake lines to the LSV. But now you've worked on the lines right at the LSV, and the master pumped air into it as well. If you don't have the clearance underneath to persuade what's left of the bleeder, you may have an easier time removing the valve from the truck and extracting the bleeder on the bench. If it's totally rounded, you may have to resort to drilling and extracting or welding a nut to it. If you can get it out without screwing up the valve, you can just put a new bleeder in the hole and hopefully be good to go.

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First, you are always supposed to top the reservoir off as you bleed, don't let it get below the low mark. Second, if the split in the rubber allowing outside air to get in, that is bad. Brake fluid will absorb moisture from the air and that will cause corrosion in the system. The fact that it sucked the diaphragm in tells me that the fluid was too low.

I did keep filling the reservoir full while bleeding..always kept checking...did that...but when bleeding the system there's a lot of fluid being pumped out/ down, so if it's sealed 100% it's not going to want to drain out to the bleeder valves right? That's what caused that diaphragm thing..I bled the system a LOT.. we used a lot of fluid. Cheers

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Huh, I always thought the diaphragm design was a domestic thing. My WD21 doesn't have one. My understanding is that the diaphragm is supposed to flex and follow the surface of the fluid, allowing air to come and go above it as the fluid level rises and drops below but keeping the two separate. Probably worth replacing at some point but I doubt it's what's screwing up your bleed.

 

You might get lucky with a gravity bleed but I suspect the LSV's got an air pocket in it that will only come out through the bleeder. It makes sense that you didn't have to bleed it when you did the front lines--air would have to go a long way to get from the front brake lines to the LSV. But now you've worked on the lines right at the LSV, and the master pumped air into it as well. If you don't have the clearance underneath to persuade what's left of the bleeder, you may have an easier time removing the valve from the truck and extracting the bleeder on the bench. If it's totally rounded, you may have to resort to drilling and extracting or welding a nut to it. If you can get it out without screwing up the valve, you can just put a new bleeder in the hole and hopefully be good to go.

Thanx for the reply. The Diaphragm doesn't touch the fluid even when the resv is full. That LSV! I guess I'll try to get the rusted nutz & bolts removed from that. Someone suggested I loosen the highest brake line on the LSV and gravity bleed it. It's raining an blowing like **** out there. I'll try and talk myself into doon it guess.

I don't know what else to do so..ya. Thanx man.

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Huh, I always thought the diaphragm design was a domestic thing. My WD21 doesn't have one. My understanding is that the diaphragm is supposed to flex and follow the surface of the fluid, allowing air to come and go above it as the fluid level rises and drops below but keeping the two separate. Probably worth replacing at some point but I doubt it's what's screwing up your bleed.

 

You might get lucky with a gravity bleed but I suspect the LSV's got an air pocket in it that will only come out through the bleeder. It makes sense that you didn't have to bleed it when you did the front lines--air would have to go a long way to get from the front brake lines to the LSV. But now you've worked on the lines right at the LSV, and the master pumped air into it as well. If you don't have the clearance underneath to persuade what's left of the bleeder, you may have an easier time removing the valve from the truck and extracting the bleeder on the bench. If it's totally rounded, you may have to resort to drilling and extracting or welding a nut to it. If you can get it out without screwing up the valve, you can just put a new bleeder in the hole and hopefully be good to go.

Your right. Almost all of my experience is on domestics. Now that you mention it, the Nissans do have a gasket instead of a diaphragm. Same idea though, have to keep the fluid separate from atmosphere so it doesn't absorb moisture.

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I had a bad brake pedal from the moment I bought my Pathy. It didn’t do emergency stops properly. Mechanics said it was fine, but were wrong.

I bought a used MC. No change.

Bled it 3 times. No change.

Bought a NEW MC. Mechanic installed and bled. No better.

 

Then I bled it with a vacuum pump.

At first, it got air, then just pure fluid. But then I sealed the MC and held vacuum. That pulled a crap-load of air (finally).

Probably from the LSV, which I couldn’t bleed for the same reason as you.

 

I strongly suggest you vacuum bleed rather than pressure-bleed or gravity bleed.

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I had a bad brake pedal from the moment I bought my Pathy. It didn’t do emergency stops properly. Mechanics said it was fine, but were wrong.

I bought a used MC. No change.

Bled it 3 times. No change.

Bought a NEW MC. Mechanic installed and bled. No better.

 

Then I bled it with a vacuum pump.

At first, it got air, then just pure fluid. But then I sealed the MC and held vacuum. That pulled a crap-load of air (finally).

Probably from the LSV, which I couldn’t bleed for the same reason as you.

 

I strongly suggest you vacuum bleed rather than pressure-bleed or gravity bleed.

UPDATE - we bled the brakes again with my nephew( didn't know if wifey was doon it correctly) then started it - the brake pedal is still very low but the brakes actually worked when I put it in gear. Took it down the street and hit the brakes 4 - 5x - it activated the ABS and the tires wud skid and then release just like they're supposed to. No leaks & the reservoir is full.

I guess it's GOTTA be the damn LSV!

How do mean U sealed the MC - how? With what? I want this finally FIXED or I'll need a sponsorship for Dot 3 brake fluid..

I'll be working on possibly borrowing a vacuum bleeder asap. It shud be a lot easier sliding around on my driveway with the ice out there.

Thanx very much for taking the time to reply on my behalf.

Cheers

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UPDATE - we bled the brakes again with my nephew( didn't know if wifey was doon it correctly) then started it - the brake pedal is still very low but the brakes actually worked when I put it in gear. Took it down the street and hit the brakes 4 - 5x - it activated the ABS and the tires wud skid and then release just like they're supposed to. No leaks & the reservoir is full.

I guess it's GOTTA be the damn LSV!

How do mean U sealed the MC - how? With what? I want this finally FIXED or I'll need a sponsorship for Dot 3 brake fluid..

I'll be working on possibly borrowing a vacuum bleeder asap. It shud be a lot easier sliding around on my driveway with the ice out there.

Thanx very much for taking the time to reply on my behalf.

Cheers

OOps - to me, it lux like the RR is the longer brake line altho, I tried it multiple different ways the last 10 f****n times. Your thots?

Thanx

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I had a bad brake pedal from the moment I bought my Pathy. It didn’t do emergency stops properly. Mechanics said it was fine, but were wrong.

I bought a used MC. No change.

Bled it 3 times. No change.

Bought a NEW MC. Mechanic installed and bled. No better.

 

Then I bled it with a vacuum pump.

At first, it got air, then just pure fluid. But then I sealed the MC and held vacuum. That pulled a crap-load of air (finally).

Probably from the LSV, which I couldn’t bleed for the same reason as you.

 

I strongly suggest you vacuum bleed rather than pressure-bleed or gravity bleed.

Which brand/ type vacuum pump did U use? Hand pump operated type.... electric? Just curious as to which one werx best.

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You can get a decent one at princess auto. I think you're getting there but still have massive air in the system. CT is insane expensive for brake fluid. Try somewhere like carquest or a discount parts place.

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Hey Brian, sorry for the delay in answering.

I used a mityvac hand pump to vacuum bleed a few times with no luck.

What worked for me was a vacuum bleeder that hooks to an air compressor. Like this one: https://m.youtube.com/watch?v=XIuj2a6tx6Y

 

The reason is that the LSV is a high spot. Every other method of bleeding uses a slow movement of fluid which won’t carry the air bubbles along so they will stay in the LSV.

Without opening that bleeder you need something that moves the fluid fast enough to carry the bubbles downward.

So the vacuum pump that uses an air compressor works.

I had to sacrifice a whole quart of clean fluid to get it, but brakes have been great for 2 years now.

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Hey Brian, sorry for the delay in answering.

I used a mityvac hand pump to vacuum bleed a few times with no luck.

What worked for me was a vacuum bleeder that hooks to an air compressor. Like this one:

 

The reason is that the LSV is a high spot. Every other method of bleeding uses a slow movement of fluid which won’t carry the air bubbles along so they will stay in the LSV.

Without opening that bleeder you need something that moves the fluid fast enough to carry the bubbles downward.

So the vacuum pump that uses an air compressor works.

I had to sacrifice a whole quart of clean fluid to get it, but brakes have been great for 2 years now.

Awesome - thank you! - that makes a lot of sense.

but U said U sealed the MC - how? with something other than the resv cap?

I have a fresh quart sitting here ready to go - the truck is almost useless with brakes like these.

I'll see if I can get one locally today so I can bleed tomorrow.

Cheers and thanx again.

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Not sure how well this would work but you could try a plastic bag, and then put the cap on. The cap should be sealed regardless or moisture would get in the fluid.

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Questions:

1. What's the difference between a quote and multiquote?

 

2. Do you think it's worth the trbl to replace the LSV with a used one?

I found an Auto Recycler near here called You Pull It. .. ( the description says it all)..waiting to see if they've got an LSV from one of their 2 yards.

http://www.upullit.ca/elmira.php and how much $$$ if I pull it ..woah - ( that didn't sound right) haha

ooooor..

 

3. Do U think I can free up my rusted one? I sure it's not working from the rust.

If I can remove it without busting off any bolts I can fix the bleeder while I'm at it.

It's a PITA to do but I can't beg, borrow or steal a pneumatic bleeder anywhere so far except for on line from the USA.

They start at $130.00 in my city...not $30. I'm not spending that for one use.

 

4. When are they switching to new servers?

 

5. Will the new servers make it possible to post pix and video easier?

If I didn't have to jump thru 10 flaming hoops to post a picture or two I'd do that.

I once spent over an hour with a post just to have it all dis-appear when I tried posting.

 

6. Cheers?

 

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MultiQuote allows you to quote multiple people at one time, so you don't have to make multiple posts to address several people. Just click MultiQuote on all the posts you want to quote then there should is a button that says Reply to X Quoted Post(s). After clicking it you make your post like normal, just with multiple quote blocks.

 

Pictures can be a pain, out of all the sites I've tried I like postimage.org best. I usually try not to do too many pics per post to avoid losing a lot of work. Also, the reason pictures have to be stored externally is to keep the cost of running the forum down. I think Mr. Jim still pays for it; you don't have to pay dues, so a small inconvenience to help keep the bill down for whoever foots the bill is well worth it in my opinion... Unlike other forums, NPORA doesn't have ad banners all over the place, which I really appreciate.

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You might get lucky with a used LSV. Make sure the bleeder turns before dropping money on it. I'd be inclined to pull the one you've got and see if you can free it up before buying a used one. Either you get it working and don't need to buy a used one, or you know exactly what to check the used one for before handing money over.

You posted elsewhere about deleting the LSV. The diagram in the '96 manual shows an LSV for 4WD trucks only, and the '04 manual shows no LSV at all. The diagram on BR-6 of the '96 manual shows the LSV and non-LSV systems side by side, and unless there's something going on in the four-way connectors that I don't know about, I don't see anything stopping you from converting an LSV system to a non-LSV system. Besides rusted fittings, anyway. Maybe cross-ref the ABS blocks and master cylinders to make sure the proportioning wasn't altered there for LSV vs non-LSV systems before pulling the trigger on a delete, though, just to be sure you don't end up with screwy brake bias.

 

As for the forum questions: If I'm putting a long post together, especially if it's been up a while since I started, I like to copy the lot before hitting Post, just on the off chance it screws up. Haven't had an issue in a while, though. I assume the mods are busy and the server changeover will happen when it happens.

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I didn’t really describe that “sealing the MC” correctly.

I have a bleed kit with various fittings. One of which is a top that goes on the MC that allows a bottle of brake fluid to screw it upside down from the top.

 

It let me pull a LOT of fluid through without having to keep running back and forth to keep the MC full.

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When I bled mine, I used a long length of fishtank airline. Opened the bleed valve and crammed on the tubing. slipped on a small clamp just to be safe. ran the other end to the MC and held it in place with a clamp. Then I just got in the truck and stomped the hell outta the pedal until I stopped seeing air bubbles going past. Closed the valve and moved to the next wheel. Worked great.

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Which brand/ type vacuum pump did U use? Hand pump operated type.... electric? Just curious as to which one werx best.

I don't know - I borrowed it from my mechanic buddy - it's pretty old and dirty..I cudn't tell. I didn't end up using it.

Solved my prolm -fixed!

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I didn’t really describe that “sealing the MC” correctly.

I have a bleed kit with various fittings. One of which is a top that goes on the MC that allows a bottle of brake fluid to screw it upside down from the top.

 

It let me pull a LOT of fluid through without having to keep running back and forth to keep the MC full.

Thanx again for taking the time to post. I'll post my findings at the bottom. I GOT IT FIXED!

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