with a new refurb one that also had the booster attached on it (the old one didn't have the booster). Put it on & bleed master into itself before hooking it up to brake lines. After bleeding master & hooking up lines, started at rear passanger side & began bleeding brakes. I noticed at this point that the brake pedal had to be pulled all the way up on each bleeding. Did all the way up to front passanger side & still same having to pull pedal back up, it stayed on the floor on each bleeding. Got over to the drivers front & had wife put pressure on pedal & beofre opening valve the brake pedal went all the way down to floor. I had her push the brake pedal to the floor several times & looked at each wheel & there is no leaking, not even at the master cylinder.

Any thoughts?

thanks
Garry

 

First of all I would recommend purchasing a NEW master cylinder rather than a reman unit. I had my truck several years before the m/c went out. Bought a reman and it lasted a couple months. Exchanged for another and it lasted maybe a month, I said F%&@ this and paid the difference for a NEW unit.

I used that for 10 years before I switched over the 4 wheel disks and manual brakes.

Pretty tough to say exactly what the problem is, but I am curious what exactly do you mean the reman m/c only came with a booster? Are you saying you switched from manual to power brakes?

Also, with a pedal going to the floor with ALL bleeders closed you must have a ton of air in the system, however, the master cylinder has internal springs to push the pistons and therefore the pedal back into position.

Something is screwed up in that regard. Easist thing to check is to make sure you didn't crank too hard on the pivot bolt on the pedal for now.

Josh

 

yes, I went from manual to power brakes & the guy at Advance auto parts said I should just buy a new mc & booster togther & that is what I did.

Sounds like to me from the get-go that since the brake pedal never came up on its own that it is probably a mc issue, dont you? Is there anyway to know if it is the mc w/o having to just take it back?
GT

 

The m/c acted ok when you bench bled it?

What year truck are we dealing with? And was the m/c-booster for the same year?

There are several different boosters and pedal combos it's nuts.

Josh

 

You also need to check that the push rod in the booster is at the correct length.

 

I didn't bench bleed it, I put it on & bolted it down w/o hooking up the brake lines & then bleed it.
it goes on a 74'.
Also strange that when I put it all together that the manual brake pedal now with a booster didn't come all the way up to depress the stop switch.

 

While I have "bench" bled a m/c with it installed in a vehicle, it's called bench bleeding for a reason.

With the master mounted in a vise on the bench you can make sure it is level and things are working the way they should when you press in the piston.

So, I am guessing you have a combination of air in the system and a couple things funky with the pushrod. The pushrod coming out of the booster on the m/c side is adjustable.

As for the pedal and brake switch you might have to add some shims/ washers to the brake light switch stop to take up the slack so the switch will work.

When I went from power to manual the pedal came back too far and make the switch pop out of it's bracket. I had to shorten the pushrod.

Josh

 

why on earth would you go from power to manual, mine had to be almost stood on just to slow it down, I am hoping that making it power would help with that

 

I notice no difference in braking between my old set-up (power brakes with disk front drums rear or power brakes with disk front and disk rear) to manual brakes disk front and rear.

I did it to make more room to adjust the valves and change valve springs easier.

If you had to stand on the brakes to make the truck stop, something was wrong.

Josh

 

if you have discs on the front and drums on the back you need a propertioning valve to adjust the preasure for front to back

 

I thought since it was manual braking that it was due to that. I had manual brakes on vehciles in my teens & didn't remember them being so hard to brake, of course they weren't on a truck.

 

An F100 weighs less than most cars, my truck empty tips the scales at 3850 lbs.

There should already be a proportioning valve whether the truck was manual or power brakes.

Josh

 

There's also a spring-loaded needle and seat in the prop.valve that has to be retracted and held open in order to bleed the front brakes completely. NAPA sells a little c-clip looking tool that holds the rod out, but I just used needle nose pliers to retract the rod, and a very small pair of vice grips (needle-nose like) to hold the rod out when bleeding the fronts. This is with front disc/rear drums.


Pete

 

That's only on the F100/F150. You do not do this with F250/F350

Josh

 

Sorry, didn't see him mention 250/350 anywhere in his post or sig.......just took it for granted he was talking about the lighter trucks. But that's good info, didn't know that. I've never owned anything bigger than the 150......


Pete