97catintenn

Hello everyone,

My brake pedal now goes almost to the floor before the brakes start to slow the truck down. The pedal is very soft too, so it easily goes all the way down.

I've bled the brakes but it didn't help.

What could be the problem?

JBradley500

im subscribing to this thread to see peoples opinions... i drove my truck home (6-700 miles) and then let it sit for 2 weeks.. went out and it was doing the same thing.

wannadiesel

If nothing is leaking it's the master.

97catintenn

Cool, that's easier than replacing the booster

Thanks

Onemoparnut

When the booster goes it usually makes the pedal hard as a rock.

jbawden

Here is another thread dealing with the exact same issue. It may not be the MC.

https://www.dieseltruckresource.com/...d.php?t=271509

97catintenn

Well, now I have found that the rear wheel cylinder is leaking. I didn't thinkg the rear brakes would cause my pedal to go all the way to floor, because I figured if the fronts were working good, then that would keep it from flooring.

So, as I was bleeding the fronts, every now and then, the rear resivoir would need just a little topping off. Which, I thought was weird, but it wasn't much and I was almost done with the fronts and what I thought would complete the brake service. I didn't think anymore of it.

I drove the truck for a mile and back, and didn't notice any fluid loss. But today, I parked in a fresh clean spot, and after an hour there was a puddle by the rear tire...now that looked odd!!

So, instead of picking a MC at advance, I picked up a wheel cylinder. I'll know in a couple of hours if that solves the problem.

ppiggppenn

That's good to see, ... WC is a lot cheaper and easier than a MC. And chances are your shoes will be OK too because of that "slinger" ring in the hub that keeps the leaked fluid running outside the drum.

maybe368

A leak anywhere in this system can cause the pedal to go to the floor. If you end up replacing your mc,(and I have a sneaky suspicion that you will) it is better, IMHO, to replace the mc and booster as a mated pair. If you search on this board, you will find that this is a very common problem with these trucks. There must be a very common cause Right??????...Mark

KD93

My MC leaks like a darned sieve. I believe it's kind of normal for our trucks. I used the $0.02 fix, a copper underneath each contact point where the wire presses down on the lid.

97catintenn

I agree, I just didn't want to do the pair because I did both of them 4yrs ago.

Check out my shoes They're a little thin. I'm opening up the other side now...

97catintenn

*************FIXED***************

Looking at the pic above, the brake fluid must have caused that side to deteriorate...cause the opposite side was still good.

Anyway, just wanted to give a closing post saying that the job is complete. Master was not replaced. I replaced both wheel cylinders and pads, put it all together. Still had a really soft long pedal. Manually adjusted the rear brakes, drove it...still had a long soft pedal. Manually adjusted and drove it two more times, and now is perfect!

I just takes a few times to get the rear pad/shoes evenly adjusted. You can adjust them to the point where you feel a little drag, like you want. But when you are adjusting them, you are usually only moving one pad. Once you drive the truck, then they center up in the rotor, and you won't have any drag. So, that's why it takes a couple of times to get it right.

Thanks for all your input everyone.

Matt