Help! Just rebuilt from frame up a 1982 F150 2wd,4.9L,power brakes, flairside. all items have been replaced on the brake system including master cyl,vac chamber,lines etc, except the distribution block. I bleed the brakes starting at the left rear,then right,then front. I got fluid from all cyls' air went through,used 2.5 cans of fluid. Problem: Brake pedal gets hard then goes soft. Brake pedal is not the same height as clutch pedal. I thing I have the wrong size shaft in the vac chamber. I don't think that is what is causing my problem. Any ideas?? Thanks Art

 

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[This message has been edited by max mitchell (edited 03-22-2001).]

 

When you're bleeding, caution your helper (the one who's pushing on the pedal) to not push all the way to the floor (she yells out "almost" and you cut off the flow).

Be sure that you only let the reservoir go down 50% during each bleed -- and have the helper lift up the pedal slowly, so as to not suck in any air (due the little vortex like water going down a drain).

It sounds to me like you're sucking in more air just as you've gotten the thing bleed-out -- and are starting over.

The easiest way (albeit expensive) for a one-person job (especially if you're gonna do it often) is to get a pressure bleeder -- which essentially caps the master cyllinder reservoir with an air-tight cover -- and gently applies pressure and fluid as you take your time with each wheel cylinder.

Hope this wasn't too basic.



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Y2K™ Jim - N8JG@Hotmail.com

Toreador Red, Keyless XLT SC SB 5.4L E4x4 4wDisc/ABS, 3.73LS, Skid, HD 7700# Towing, LT-245's on Chrome, Tube-Steps, Captain's, 6CD, Tonneau, named: "Nick"

 

she yells out "almost" and you cut off the flow
i heard this before somewhere

 

Thanks for the quick responce. I followed the instructions for bench bleeding the Master Cyl, got good flow out of both ports. I also made sure that my assistant pumped up the pedal 6 times and held down same as I opened the bleed fitting on the cyl's starting with the farest from the master cyl ending up on the front drivers side. IMADE SURE THAT HE DID NOT RELEASE PEDAL UNTIL I CLOSED THE FITTING. After bleeding the pedal was hard but not equal height compared to the clutch pedal. After a few minutes the pedal went soft. There are no leaks in the system. everthing is new except the dist block. I got good flow and pressure from each cyl when bleeding. Confused all should work?

 

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[This message has been edited by max mitchell (edited 03-22-2001).]

 

does it have a power booster ?

 

Yes it has a boster. Yesterday I removed the booster and Master cyl. Went back to the bench and rebleed the master cyl, got good floe no air from both chambers. Measured the rod according to spec's for clearance from power boster rod to Master cyl piston, all ok. Rebleed the sys from longest away to close to master cyl. Still pedal does not match cluch pedal height and Pedel gets soft after a few min. Then went back to exchange the master cyl. Reinstalled an got same problem. I am doing things right but I am starting to get #$#$%%^^%^%$. Thanks for help any more ideas?

 

Hmmmmmm.

"...After a few minutes the pedal went soft..." -- could you have rear brakes that are way out of adjustment?

I wish I knew what you meant by going soft.

If your rears were out of adjustment, you could pump them up (spread the shoes against the drums) and have a nice hard pedal -- only to have the shoes slowly pull back away from the drums by the return springs -- with the pedal going down a bunch upon application after a reasonable wait.

In this scenario, you'd be able to 'pump them up' -- with a firm pedal -- only to have the cycle repeat.

If 'soft' means a mushy pedal that cannot be pumped 'hard' easily -- and if there's no fluid going anywhere, I'd bet on the booster.

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Y2K™ Jim - N8JG@Hotmail.com

Toreador Red, Keyless XLT SC SB 5.4L E4x4 4wDisc/ABS, 3.73LS, Skid, HD 7700# Towing, LT-245's on Chrome, Tube-Steps, Captain's, 6CD, Tonneau, named: "Nick"

 

i bet its a aftermarket power booster

 

yes,it is a aftermarket booster. Ford stoped making replacement in 1996. Soft pedal means right to the floor again.I am a little confused with the operation of the booster! Shoudn't I have brakes with the engine not running? There will not be power brakes, right? I bleed the brakes with the engine off. Is that my mistake? If it is I feel stupid. I will try bleeding again with eng on this weekend. Thanks everyone for the tips. Art

 

Bleed brakes with the engine off. They will have a very mushy feeling with no vacuum in the booster).

A very common mistake results in sucking in air during the 'pump-up' portion of the process -- and it involves sucking air into the little piston when the fluid in the reservior goes down (down due to your having let out fluid during the last pump).

So, have your helper release the brake with a deliberate but not blazingly-fast lift of the leg -- and then push (or pump) at a moderate rate.

Time and time again, I've seen jobs that were one bleed away from perfect -- become 'start-overs' due to not paying attendion to the reservoir level -- or an over-zealous helper.

If it doesn't bleed out fairly easily (once you're sure you're doing things right), then you have a different problem (others above have outlined).

Be sure your brakes are adjusted!!!



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Y2K™ Jim - N8JG@Hotmail.com

Toreador Red, Keyless XLT SC SB 5.4L E4x4 4wDisc/ABS, 3.73LS, Skid, HD 7700# Towing, LT-245's on Chrome, Tube-Steps, Captain's, 6CD, Tonneau, named: "Nick"

 

Lets review what I have done.

1.Replaced the following
Rear shoes, cyl, all new springs and hardware.All new Brake lines (from inline tube).Front Calipers,pads and rotors and brake lines new booster, and master cyl.

**Did not replace distribution valve.

2. What I did so far:
Bleed system 5 times started with farest away ended up closet to master cyl. Got fluid flow from all cyl, no air.

I had my assistant with eng running pump pedal 5 times and held down.(pedal firm)
While he held down I opened the bleed port on cyl fluid squirted out.Did this for all cyl.No luck pedal still went to the floor.

I removed and replaced the master cyl.ordered a new booster( because I thought the rod was to short on the unit I bought earlier. Compared them, they were the same.Verfied rod to master cyl proper lenth per spec.All ok

3. Bleed system 3 times yesterday no luck.
Checked rear adj of brake shoes. OK

I am confused . I did it all. the only thing I did not replace was the distribution valve. If it was bad I would have no flow of fluid from either the front or back.


Did I leave anything OUT? Please help need brakes
+

 

Was there a happy ending?

 

The best way I have found to bleed the brakes is to use a hand held vaccum pump. You just loosen the bleeder valve on the wheel, attach the pump to it, then start pumping (remove the master cylinder cap too). Don't need anyone to pump the brake pedal. The fluid goes into a little reservoir on the vaccum pump. You will see air bubbles all the time while doing this. Leads you to believe that there is air in the entire system! but it is just air leaking in from the threads around the bleeder valve.

I was doing a fluid change anyway, and just kept pumping until the fluid came out clear (I did remove all the old fluid from the master cylinder first and refilled with new). Check the master cylinder after each wheel, and refill.

I have also done this to bleed my dad's '71 F250. Worked great. Very firm pedal afterwards. Hope this helps.


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1997 F150 4x4 Off Road, SuperCab, Short Box, 5.4, Royal Blue/Silver, K&N, Gibson SS, LT265/75/16 Wild Country APT's