PM on Brakes

[BenMara]

Well i bleed the system 4 times in the last 3 weeks still have to pump brakes to stop did the test to see if booster is bad depress brakes then start should go down a lil but mine stays on floor so i dunno if its the master cylinder when i press the brake it goes to floor with resistance

No air in lines

Tkx for the help
Ben

 

[Ebag333]

Are you bleeding all 5 points?

You can bleed the fronts and the rears to your hearts content, if you don't bleed the LSPV (it's right next to your rear drivers side tire, just in front of the wheel well, you can't miss it) you'll experience soft brakes.

I had extremely soft brakes, bled the fronts and rears with only limited improvement. Bled the LSPV, and it made a world of difference.

 

[hzavarce]

Are you bleeding all 5 points?

You can bleed the fronts and the rears to your hearts content, if you don't bleed the LSPV (it's right next to your rear drivers side tire, just in front of the wheel well, you can't miss it) you'll experience soft brakes.

I had extremely soft brakes, bled the fronts and rears with only limited improvement. Bled the LSPV, and it made a world of difference.

Exact same thing happened to me. DO bleed the LSPV

 

[BenMara]

did all 5 points every time
I still think its the master cylinder and/or booster

 

[Ebag333]

did all 5 points every time
I still think its the master cylinder and/or booster

There is a procedure to bleed the master cylinder in the FSM (which is a pain). If you got enough air in there, you could have similar problems.
(Tip, if you decide to bleed the master cylinder, have some good flare nut wrenches, don't use a box wrench. Ask me how I know...and why I own the last availible-in-the-US pipe that attaches there. )

When you bled each time, did you see air come through the lines? How are you bleeding (some of the self bleed or vacuum bleed kits can actually let air back in the lines)?

Looking at the brake booster assembly check, it seems to me that if your brake pedal is already to the bump stop on the floor, trying to perform the two checks is an exercise in futility as the both require that the brake pedel be off the floor when you're pushing down on it.

Have you checked all four calipers to make sure they're functioning properly?

I'm still leaning towards air in the lines and/or master cylinder. It might be worth the coin to take it to the dealership or a good mechanic, and have them power bleed the brakes.

 

[BenMara]

when bleedin only saw air in LSPV, i did the bleed seq in par to what is stated if FAQ

I need to get a FSM, and quit askin so many question on here, brakes seem to be workin just takes more effort to stop have to pump pedal to stop, when i was backin off trailer brakes wouldnt hold from slamin front bumper into trailer.

What 2 checks are you referring for checkin the brake booster.

Well from talkin to PO only brake related thing hes dont is new front remaned calipers and slee lines for the lift

im contemplating gravity bleed

 

[Cattledog]

Keep bleeding the LSPV. It take ALOT of fluid to get all of the air out.... Took about 2 quarts for me at the LSPV.

 

[Ebag333]

when bleedin only saw air in LSPV, i did the bleed seq in par to what is stated if FAQ

If you see air from the LSPV, then you aren't getting any/much pressure (to speak of) to your rear brakes. While you do stop mostly with your front brakes, your rears make a significant difference in your stopping capability.

when i was backin off trailer brakes wouldnt hold from slamin front bumper into trailer.

Your towing a trailer with soft brakes?

Are these only problems when towing? Or all the time?

What 2 checks are you referring for checkin the brake booster.

At this point it doesn't matter because from what you've told us the brake pedel is all the way to the floor. Until that's resolved the BB checks (which require that the brake pedel not be on the floor) can't be done.

Well from talkin to PO only brake related thing hes dont is new front remaned calipers and slee lines for the lift

Your Slee lines might be letting air into the line, it's been known to happen (usually from improper install, lines getting pinched or rubbed, etc).

If you're seeing air from the LSPV, check the lines that connect to the LSPV for wear/pinching/damage/etc.

im contemplating gravity bleed

Gravity bleeds are for trailers, they won't work for this purpose.

Either keep bleeding the lines until you don't have any air in them or take it to the dealership or another mechanic who can power bleed them. In your case it may end up being cheaper/easier/safer to take it in rather than doing it yourself. Especially with the LSPV it's very easy to let air into your lines through the bleeder screw.

I used nearly 3 quarts of fluid to get all the air out, but a fair amount of that was wasted due to me cracking the LSPV bleeder screw open too far (and letting air in).

 

[BenMara]

was backin off the trailer when the brakes wouldnt let me ease off slowly ill look over the rear lines and bleed the LSPV again

 

[Miescha]

How are you performing the brake bleed each time? Power Bleeder, vac bleeder, or the old fashioned (argueably best) two person bleed?

If doing this by yourself especially, are you certain you kept the brake fluid resevoir full? If the fluid gets too low, you will certainly get air in the MC and once that happens, no amount of bleeding at the 5 bleeder valves will matter until you bleed the MC (which requires two people).

I say bleed the MC just to rule it out at this point, then re-bleed the entire system while making certain you don't let the resevoir drop too low and re-introduce air into the MC.

Good Luck!

 

[BenMara]

2 person bleed, bleedin the MC? care to elaborate?

 

[Firedog]

If you suspect that you still have air in the lines, build a pressure bleeder. That is what I finally had to do to get a good pedel in my '93.

Check out the thread here
https://forum.ih8mud.com/80-series-tech/171235-spongy-low-brakes-cant-fix-please-help.html

 

[jsuthey]

Refer to the FSM,lots of good reading in there! If you don't have one yet try downloading that section brakes/bleeding(search for that post on downloading).Good book to have ,keep looking for a used one,I scored a nice one for 40bucks.
John

 

[BenMara]

yea i need to get a FSM one day anyone wanna help me out ill paypal some $$ to anyone that has already DLed it

 

[hj60]

Ben-
You broadband or dialup?
I've got a copy on CD.

 

[BenMara]

PMin you

 

[Miescha]

2 person bleed, bleedin the MC? care to elaborate?

On the two-person bleed, I'm just referring to the traditional method of having one person pump the brake pedal while the other opens the bleeder valve just enough for flow to start and then close the valve before the person pumping the pedal releases it (possibly pulling air back into the system).

It is important to have a really good fitting on the bleeder valve or air may get sucked back into the system from around the connection (even though you have a tube going into your catch canister with enough fluid in the canister to at least cover the drain tube and prevent air being sucked back into the system at this point).

On Bleeding the MC, there is a procedure in the FSM for this, and there is no discussion of using a pressure bleeding device or pump for single person bleeding, so the FSM only discusses the traditional two person method.

I'm only aware of this b/c I used a pump to bleed my brakes at one point when I had to do it alone, and didn't keep up with the fluid level in the MC. As a result, I finished and thought everything was fine, but when I backed away from the lift using only the slightest amount of throttle I nearly hit the lift behind me b/c I had no friggin brakes! I was stumped and bled everything again and still no dang brakes (even though I wasn't getting air at the bleeder valves and I was keeping the MC full).

I went searching through the FSM to find reasons for no brakes and discovered the issue of air in the MC. IIRC, it calls for loosening two hard lines on the MC and bleeding the system via the brake pumping method. In the end, it worked, and so did my brakes.

Though I was relieved and happy to have my brakes back, I was pretty pissed that I screwed this up and caused so much extra headache. I'll certainly never let the resevoir drop too low again.

 

[Firedog]

On Bleeding the MC, there is a procedure in the FSM for this, and there is no discussion of using a pressure bleeding device or pump for single person bleeding, so the FSM only discusses the traditional two person method.

I'm only aware of this b/c I used a pump to bleed my brakes at one point when I had to do it alone, and didn't keep up with the fluid level in the MC. As a result, I finished and thought everything was fine, but when I backed away from the lift using only the slightest amount of throttle I nearly hit the lift behind me b/c I had no friggin brakes! I was stumped and bled everything again and still no dang brakes (even though I wasn't getting air at the bleeder valves and I was keeping the MC full).

Correct
Bleeding the MC is done the same way as bleeding the calipers.
You have someone "pump up" the brake system and hold pressure while you loosen the hard line fitting at the master cylinder. Fluid and air come out and you retighten the fitting while the other person holds pressure on the brake petal. Repeat on each fitting until no more air comes out.

 

[hj60]

Mityvac sells a reservoir for this. Part # MVA6832. You fill it with break fluid and turn it upside down on top of the master cyl reservoir. It keeps the MC fluid at the proper level for bleeding
I always vacuum bleed.
But if I can leave it over night, I gravity bleed.

 

[BenMara]

well i went to get some flare nut wrenches from SnapOn guy durin break at work but didnt have any so im just gona work on PM on front axle this weekend and some other issues but will be back on the brakes weekend after next
ill keep this updated

EDITED:
Just talked to PO again, he said this brake issues was even werse before he got the current remaned brake calipers. hmmm....