Really strange brake issue..

[AllenKarber]

Or maybe not...

I've been working on getting my '64 running again. It sat for a year,and when I pressed the brake pedal the other day it went all the way to the floor. The brakes were fine when I drove the truck last. While I was sitting in the truck and pumping the brake pedal I kept hearing a whooshing noise. I finally figured out it was coming from the gas tank filler neck. How in the world is that happening? Am I missing something?? I have manual disc/drum brakes with a dual reservoir m/c.

[neto]

That is very strange. Did you follow the brake lines to make sure someone didn't connect a brake line to the gas line. Manual brakes so no vacuum line, so can't be there.

[66redw/white]

sounds to me like the inside of the master cylinder rotted

[markeb01]

The pedal going to the floor is almost certainly due to a leak in the system. The most common places to check are the master cylinder, wheel cylinders, and the rubber hoses. If it hasn’t been used much (or at all) over several years it’s possible all are bad. Wheel and master cylinders don’t like just sitting in one place. The other side of the cylinder beyond the seal and piston can get rusty. When the brakes are used again the seals are pushed over the rusty part of the cylinder and tear them up causing fresh leaks that weren’t there when the vehicle was last used.

The hoses should be replaced even if they look okay, because they frequently deteriorate from the inside out and deposit more crud in the system.

As for the whooshing sound, that’s an odd one. Perhaps the cab is tight and pedal movement is moving air past the filler neck seal, or the noise is bouncing around the cab and just sounds like it’s coming from the filler neck?

[AllenKarber]

Yeah, I need to bleed the brakes for sure. No doubt about that. I was too worn out from work this week to do so.

I went and bought another gas cap today,and the whooshing went away. And I had more pedal,but I still had to pump the brakes to stop. My front calipers,hoses,M.C.,and lines are only a couple of years old,but I have no idea how old the wheel cylinders are. The rearend came from a fairly low mileage '71 back in '97 so they might even be the original ones. Probably my next step along with bleeding the brakes.

Thanks for the help everyone!

[jocko]

so, you're driving it with this problem??!! YIKES.

I'm with markeb01 - gotta have a leak somewhere. I'd bet you may have had some wheel cylinder boots rot if it sat for a long time. I'd say before you go thru the bleeding process, pull all your wheels and look for obvious signs of a leak - and fix that, then bleed. If no obvious signs, then, hmmm.... not sure. Glad you got your whistling cab issue solved!

[fastwillie 696969]

i bet from sitting the brake fluid got condesation built up and brake fluid breaks down then eats the seals inside the mastercylinder ,you can pump the pedal until your leg fell off ,you need to change m/c and flush the old brake fluid out and have fresh fluid ,check wheel cyl.,hoses ,calipers , im just sayin

[awbrown]

Is this a C50 ?? I remember the farm trucks we had years ago when i first started to drive had the brake boosters under the cab and the booster had a vent that came up to the floorboard right below the gas tank .....

[AllenKarber]

Originally Posted by awbrown

Is this a C50 ?? I remember the farm trucks we had years ago when i first started to drive had the brake boosters under the cab and the booster had a vent that came up to the floorboard right below the gas tank .....

It's just a C10. It wasn't smart to drive the truck like it is,but I was so ready to drive it around some. I'm going to get down to business this coming weekend to fix the problem.

[Muleman100]

If you can pump the brakes and it stops and you have no leaks you may want to adjust your brake shoes. Too much space between the brake shoe and the drum will require more pedal and a quick pump of brakes make up that distance. just a thought other than tou may need to replace your master cylinder, make sure you bench bleed first.

[AllenKarber]

Originally Posted by awbrown

Is this a C50 ?? I remember the farm trucks we had years ago when i first started to drive had the brake boosters under the cab and the booster had a vent that came up to the floorboard right below the gas tank .....

I do love those old farm trucks! They still use some 60's and 70's vintage trucks on some of the soybean farms around here.

If you can pump the brakes and it stops and you have no leaks you may want to adjust your brake shoes. Too much space between the brake shoe and the drum will require more pedal and a quick pump of brakes make up that distance. just a thought other than tou may need to replace your master cylinder, make sure you bench bleed first.

I haven't lost a drop of brake fluid. With my luck it's probably the not very old MC,but I will check the brake adjustment.