after 4days i need help!!!

[nick_tinter]

I am the kinda person that will read and read and read before i ask any thing.Ok here it goes with another brake problem.I have a 1972 m35a2 that i have been having for a few months now and every worked great for a while and now i am having the problem with it.The brakes went to the floors about a month ago and i add fluid and did a quick old school bleed job and they worked great.I went to use the truck a 1 week ago and the brakes would work then not work so i made where i had to go and let the truck sit for 2 weeks and went to drive it and no brakes.They went to the floor,So i put fluid inn and did the old scholl way again and nothing.Today i made a pressure bleeder and start at the air pack then started from the farthest wheel from the m/c and worked my way forward.Some of them had a little air so i did it about 8 times and still nothing pedal still goes to floor.Yes i do have air pressure.I am out of ideas before i pull all the tires off and check everything.I didnt see any leaks any were also.Thnaks in advanced for any info.

 

[wsucougarx]

Wonder if you need to rebuild/replace your master brake cylinder or air pack. Have you looked at your brake lines for leaks? Youve got a leak somewhere or its escaping out of your mc vent?
Also, I make it a point to go through and replace all the wheel cylinders upon picking up my trucks. You can never be too sure on the integrity of the rubber seals in those cylinders.

 

[73m819]

With that much brake fluid added, there has to be a leak that you should see, check the back of each tire, check all 5 rubber hoses, steel lines along the frame, across the axles, there is going to be a wet spot somewhere and that spot will not be from a dog

 

[DBLDUECE77]

 

[nick_tinter]

thanks for the quick replies i am gonna look around for any leaks again.

Is there any way to tell or to test to know if the air pack or the m/c needs to bee rebuilt?

 

[jaymcb]

It's a leak, bad master cylinder, or both.

 

[mhassett]

Nick;
Give me a call.
MHassett
Bush, LA

 

[doghead]

Unless the person you bought it from, told you they completely rebuilt the whole brake system, I would inspect and completely rebuild the brake system. Not only will you find your problem, you'll also know that your brakes are in top condition after that. It will also give you the opportunity to inspect and replace any bad wheel bearings and hub seals. Then you can roll on the highways with others and feel confident you have a good brake system.

Anything less and your simply rolling on a chance and a prayer.

 

[APM215]

With that much brake fluid added, there has to be a leak that you should see, check the back of each tire, check all 5 rubber hoses, steel lines along the frame, across the axles, there is going to be a wet spot somewhere and that spot will not be from a dog

 

[73m819]

a bad M/C will not use fluid, just allow it to bypass or come out the front, as your post, you had to refill at least twice, if not more, and bad enough to bleed each time, the first time the M/C was empty with the pedal going to the floor after running with no problems should have told you that there just might have been a problem, NOT fill and bleed and go

 

[DeucesWild11]

Mine is leaking at the hoses that connect to the wheels. I noticed the brake fluid not on the ground but drip marks on the inside of the front tires. Now I just need to order the correct hoses and replace..

 

[dozer1]

I agree with Ron and the others that there most likely is a leak that you should see. If the fluid is going somewhere and you can't find a leak to save your life, it could be filling the dustboot on the MC. I have seen this happen before and couldn't figure it out myself, untill it popped like a big zit.

 

[pctrans]

I already know SOME of you will say I'm wrong, but it works. Find/fix your apparent leak. Drain the fluid in your master cylinder, and refill with DOT 3. Then pressure bleed your lines (using DOT 3). Much cheaper and it will swell all the seals in the system.

 

[nick_tinter]

i think its the m/c so i just ordered one.thanks for all the help.

i bleed the breaks a few times to make sure i didnt have air in the lines and didnt find any leaks.and i did talk to a nice guy that helped me out with the problem

 

[gimpyrobb]

Why guess? Have you adjusted the brakes? If they are all out of adjustment, that could be the issue too. Adjust them and re-bleed the system, then post back up.

 

[doghead]

It is very easy to remove the dust boot on the Master cylinder rod and see if it is leaking. Very very easy, one person task. You can sit right there and pull down on the brake pedal lever and watch it.

Your airpack may be filling with brake fluid. It could hols about a gallon and you'd never see it.

Guessing with brakes will kill someone. You need to do a total inspection of your brake system, if it has not been done in the last year or so.

What brake fluid have you been using?

 

[hndrsonj]

If there's no fluid leaking anywhere, my bet is an internal leak on the airpack.

 

[clinto]

thanks for the quick replies i am gonna look around for any leaks again.

Is there any way to tell or to test to know if the air pack or the m/c needs to bee rebuilt?

You can plug the outputs of the airpack and master cylinder.

1. Plug airpack outlet-if you have a stiff pedal, the problem is downrange. If you have no pedal pressure, it's either the airpack or master.

2. Plug master cylinder. If you have good pedal, you know the master is good. Soft or no pedal, master is no good.

 

[nick_tinter]

i am gonna put a new m/c and re bleed the breaks to see what happens.

 

[SMOKEWAGON66]

...Am i missing something here? 2 replies from DH on a mechanical question thread, and not once did he mention the TMs....Im scared. LOL.

But to keep on track here...as stated above, it does sound like an internal leak in the AP...start there...then do what DH suggested and go through the WHOLE system front to back.