The Stovebolt Site Forums The Parking Lot Big Bolts pressure bleeder

Service manual says that manual bleeding will only work on 3/4, 1, and 1 1/2 ton without Hydrovac, all others require a pressure system. Would anyone know how to make such a device as I am sure nothing is available for this era machine? I have tried manual bleeding and it just doesn't seem to get it enough, therefore the pedal needs pumped to get a stiff brake.

Thanks.

Yes, I made one out of a half gallon weed sprayer. Was refered to a web site with the How-To, which I no longer have but: You need a spare master cyl cap/cover drill out for a fitting to connect the hose from your pump sprayer, also drilled a hole in the top of the sprayer for a 20psi press gauge. Screw in your new filler cap and hose pump up to about 15 PSI, sprayer is about 1/3 full of new brake fluid, pump her up and then bleed away.

What about filling your system from the wheel cylinders up with a pump oil can . Just saw an artical about that in sport avaition mag.

Right smack in the middle of doing the same thing on the '48 2t. I borrowed a pressure bleeder from the local garage. They can't be used with modern systems, so the guy was in no hurry to get it back. They're fairly complicated, tank with diaphram, universal fittings for master cylinder, etc. I'd try to borrow or rent one. A question of my own: The nipple on top of the bleeder valves on the hydrovac have been replaced with screws??? I can try to fit the plastic tubing around the valve, but where would you find the right valve?

Update on the bleeder valves. I drilled (7/32) out the threaded (8-32) hole on top of the valve and tapped it 1/4-28. Ground off the bottom of a new zerk so the spring and ball fell out...instant nipple, worked slick.

Any competant parts house will carry an assortment of bleeder screws..I just bought 6 for one of my
2 ton dumps...Were only .75 ea...

I dont have any trouble bleeding brakes on the big truck without the presurre bleeder. Take any tank thats air tight and has an opening to put the brake fluid in. An old freon tank works great, Put a rubber hose from the tank to the cap on the master. The cap should have a hose barb threaded into it. Put the tank with the brake fluid on your seat or hang it up from the roof. Gravity is your friend here, just open a bleeder some where and the fliud will flow. This will work on any system old or new, you just have to have the tank higher than the master and keep fluid in it.

Thanks,

I did manufacture a pressure bleeder from an ACE 1 gallon sprayer. I added a fitting and a regulator to the side so that I could run it from an air compressor and keep constant pressure on it. We also manufactured an adapter to fit the resivoir, it has a bleed screw and extends up into to cab for easy access. This system seems to work great.

But...

I still have something going on. This system is all new/rebuilt. We have the wheel cylinders rebuilt to new condition, the Hydrovac is rebuilt to new condition, and the master cylinder is rebuilt. We also have 100% new brake lines installed. The system is fully bleed and adjusted and still the pedal goes almost to the floor. It works quite well if you pump it once or twice. It's almost as if there is not enough fluid to fill the pistons. I have the master cylinder that every auto store says I need, it is a 1 1/4 inch bore. Everything appears to be right according to the Chevy service manual. If I cap it so that I dead head the unit it works fantastic, hard as a rock with no fad, so there is no bleed by on the primary cup. The only thing left in the unit is the check valve and I have no good way to test that, although I don't really see how that would affect the outgoing oil as it is there to control the return oil.

The manual says after bleeding and adjustment with 75 pounds of force on the pedal there should be 5 inches of clearance from the bottom of the pedal to the toe board (with no mat).

I've ruled out air in the system by adjusting the pads all the way out until they can't go any further, this results in a very hard pedal with no mush or fad. As I bring the pads back into proper adjustment I continue to loose toe board clearance until finally I need to pump it for good operation. Also when the unit is fully pumped up I can only get about 4 inches of toe board clearance instead of the 5 the Chevy service manual says I should achieve. I could live with the 4 inches if it were there when the pads were adjusted properly.

As a second question, I seem to have a discussion going with some others here as to how much drag is proper on the wheels. I have never had any problems with being able to barely hear the pads wisping the drums but another says I should leave them at a point that will make the drums hot with just a drive around the block. I know that "lite drag" is subjective but is there any better methods or thoughts on this.

Thanks again for the feedback.