Bleeding booster in IH truck

We replaced the brake booster on our 62 IH truck today. We have bled, bled, & bled. We do not get air any where and have ran 2 quarts of brake fluid through it. We still have no "pedel." Am I missing something? Ours is a three line setup, and does not have a bleeder on the booster anywhere (that we can find).

Thanks

They are horrible!!!!
Use the fittings at the booster to bleed the air out. Old mechanics fill the chamber and piston while it is off the vehicle. Even then it is a chore to get it pumping. Make sure the piston is returning to the stop (pushrod not too long) if it does not, it cannot uncover the intake, and will remain air locked. Pressure bleeding can be a major help. Use an adapter on the reservoir to put 3psi of fluid pressure in the system, then bleed the lines at the cylinder first. JimN

Is that a vacuum booster?? If it is then thats does not need bled. Sounds like you have a bad line some place or a bad master or wheel cylinder. Since your loosing fluid it sounds like a wheel cylinder is bad of the master is leaking into the booster and the engine is then sucking the fluid into the engine and burning it. BTDT with a bad master cylinder
Hobby farm

I'd check master-cly real close to see if its "reloading" each stroke. also, don't pump it real fast-most boosters I mess with have 1 bleeder' but have seen none-use clear hose or pressure if possible,as others suggest. If i remember,mas/cyl outlet check valve is omited when H/vac is used,makes fluid want to suck back anyway--good luck, paul

I'd check master-cly real close to see if its "reloading" each stroke. also, don't pump it real fast-most boosters I mess with have 1 bleeder' but have seen none-use clear hose or pressure if possible,as others suggest. If i remember,mas/cyl outlet check valve is omited when H/vac is used,makes fluid want to suck back anyway--good luck, paul

The booster is under the floor board. We know the old booster was bad with brake fluid in vacuum lines. We replaced several fittings and a brake line at the same time. We pressurized the master cylinder resivor, vacuum bled the rear wheel cylinders and traditionally bled the front wheel cylinders. We bled 2 quarts of fluid out of various bleed screws and fittings. We are getting no air out of the system. That is why I asked what I am missing. The pedel is easily pushed to the floor with your hand. any more ideas... please.

Sounds like the master cylinder may be bad or not going all the way home

If you take the line off the master cylinder and hold your finger over the outlet, does it make so much pressure that you can't hold it with your finger when pumping the brake pedal? If it does not, the problem is most likely the master cylinder

Some of those old boosters had two bleeders.

Our 1700 did the same thing, found the master cyl to be bad. Also, make sure the vac. line is in good shape. We had to replace that too.

I would try and find a rebuilt master cylinder. You may have to put a kit in the old cylinder if there's no rebuilt cylinders. If you find a rebuilt cylinder be sure to bench bleed it before installing. See if anyone has a Wagner brake bleeder you can use. Hal

You could try this,remove the lines from the master cylinder,or really just break them loose one at a time as somebody holds the pedal down,does it squirt fluid?If not,its your master cylinder,maybe.If it does squirt fluid,and you say there is no bleeder on the booster?Have somebody pump the pedal,then hold it down and you break the line loose going to the booster.If you dont have any fluid there,its your master cylinder,if you do,break the line on the other side of the booster and see if you have pressure.Keep on like this untill you get to a back wheel.If you have pressure to a back wheel,but pedal goes to the floor,its either the master cylinder is not working,or could be plugged up with crud,the new booster is leaking internally,(probably not)there is a wheel cylinder leaking and you cant tell which one yet,(not likely).Pressure bleeding can help if you are by yourself.If you start the motor does it get pedal?If it did that would be a sign of a trapped air bubble in the lines.I have done this before,just fill your master cylinder with fluid,then crack the bleeder loose on the longest line,with a dual system the longest other line too,and let it drip or just barely a little fluid come out.After a few hours check and make sure you dont run out of fluid in the master cylinder,then tighten the bleeders,and for me it worked and I had pedal.Somehow,if you have a lot of kinks in the lines it can trap air in there and that was the only way I could get it out.Most likely its your master cylinder,but the motor would need to be running to get the full effect of the booster and all on your pedal.You might not ever get real good pedal until the motor is running,but it should stop before it gets to the floor.My guess is the master cylinder,pull it if you dont have pressure and clean it,look for a hole in the bottom of the chambers for fluid that is full of crud.If its real clean,I would say replace or rebuild it like lots of others said too.If you are lucky,you might just clean it up and maybe put a kit in it and fix it.The trouble is trucks with brakes like that set a lot of the time and moisture collects in the bottom of the wheel cylinders and the master cylinder and corrodes into the metal.It doesnt take very much corrosion and they get to where they wont build pressure,or get stuck in the bore solid as a rock.If it sets a lot,changing the booster and the master cylinder might just be the start,you might have to fix more problems.

Ok first off Don't be suprised if the rebuilt booster is not bad, as i went thru this a couple months ago . BUT FIRST OFF why did you replace it??? ,because you had no pedal . With old juice brakes on OLD trucks better then half the time when ya think the booster is bad all ya need to do is ADJUST the brakes as that takes some getting use to doing correctly . The master cylinder only moves somuch fluid along with the booster and when ya start having to PUMP the brakes to get pedal then the brakes are out of adjustment and with most larger trucks with juice brakes there are TWO adjusters to each wheel . ANd each one has to be adjusted correctly . One also has to keep in mind that there is NO dual braking system on these old trucks and everything MUST be wright the first time . The best way to bleed these old trucks is with a power bleeder because here again the master cylinder and booster can only move somuch fluid and normaly it is not enough with the routing of the lines . But here again it all comes back to brake adjustment. One other thing you MUST also look at is the brake hoses from the steel lines to the rear axle and to the ft. wheels . It is not uncommon for them to collapes inside and stop the flow of brake fluid to that wheel or axle . This will dive you nuts tryen to fine the problem . So best to change them all as i your life along with somebody else's if your brake job fails.

Sounds like you have a Hydro Vac system. Theres a trick to doing it. It's not like a car where you just dump in fluid in the master cyl on the fire wall and try to pump it up. You need to find an old truck mechanic whose dealt with these things.