The Stovebolt Site Forums The Parking Lot Big Bolts Why ain't my booster boosting?

So here's my conundrum, I recently went through the Hydra-Vac on my truck. I reinstalled it yesterday and bled the brakes. I have fluid on all four corners, it appears I have gotten all the air out of the system, yet I have no brakes. The pedal is soft too.

The truck is pulling 20+ inches of vacuum at idle per the gauge on the dash, and if I "vigorously" pump the pedal I do get some braking action.

What the heck is going on here?

Brian,

What is the brand, model, year of the truck?

Is everything in the braking system original-style parts?

Have you adjusted the brakes (brake shoes)?

What procedure did you use for bleeding (is it as described in your Shop/Maintenance Manual)?

The truck is a '66 C50.

All original style parts in the braking system.

The shoes were previously adjusted so I know they are OK.

Bleeding was performed with me pumping the peda, putting a big rock on it and then cracking the bleeder on the slave cylinder. I repeated that process around the truck.

Was that wrong?

Any ideas are welcome!

mmmm, I'm not big bolt guy but sounds like you may have air between the slave and the wheels.

ive tried using a stick by myself with limited results. i made a homemade pressure bleeder with mixed results and a hand vacuum pump with no results. for me the proven way with the best results was with two people. one that knows how to pump up the brakes and apply the pressure and the other one that knows how to work the bleeders with total communication between both parties and of coarse with the sequence used as stated in the maintenance manual.

Well, progress!

I enlisted the expert help of my four year old son to see if bleeding would get me anywhere today. Remember, I had NOTHING coming into this morning.

With the kiddo pumping and holding (intermittently) I was able to get some air out and the truck has brakes that are not great but working. My pop is coming over next weekend. Because we picked up some function today, having my pop and I bleeding them should get us back to where we need to be.

I'll keep you posted!

Brian

I used the Mityvac on my truck.

There is a step by step on this link:
http://www.mityvac.com/pages/info_faq.asp

I have had good luck with using a bottle with a hose stuck in it and starting with a little fluid in the bottle I connect the hose to the bleeder and make sure that the hose is into the brake fluid that I have in my container. When you pump the peddle you get air out and when you let off it has no choice, but to pull fluid back in instead of air! I run a restoration/fabrication business and I don't always have an extra hand (or foot) when I am ready to bleed brakes.

This method works well most of the time. Should work with the bleeder on the booster unit also. Sometimes you will need to bleed the master and then the booster and then the wheel cylinders!

Good luck!

Does a 66 have two wheel cylinders on each rear wheel? If so did you bleed all of them. I know I had a 64 with the 2 cylinders and I think my 65 LCF-60 does. They are a real pain.

I'm partial to Speed bleeders, awesome little critters. Replace your bleeder screws with them, attach a hose, crack a little, pump brakes 3-4 times, tighten bleeder, and move to the next one. Works for me anyway, not everyones favorite method.

As far as whether the HydroVac is workin, there's 2 ways I use to check mine. 1st, with motor off push on the pedal (pump if you need to), and crank her over. You should feel the pedal go down a bit more as the booster takes pressure. 2nd, to see if it's holding pressure well, kill the motor and pump the brakes a couple times, you should be able to hear the HydroVac chuff a time or two as it uses the residual vac pressure in the can & lines.

Hey all,

Thanks for the advice! You'll be happy to know that Goliath stops on a dime now! The major issue was air in the lines, it took having someone who "knows" what the pedal should feel like to help me pump it up as I went from wheel to wheel.

Just after I got that done, the front brake line blew out (luckily I was in my driveway at the time). I pulled the bumper and unbolted the line, bent up a new one and BINGO...I was back in business. I replaced a couple of the other lines while I was in there as well.

Thanks again guys,

Brian

If it were me and that happened, I wouldn't drive it without replacing ALL of the lines...both steel and rubber. You will always be wondering when the next line will blow.

Be safe!

Mike B

Mike, all the lines to the rear of the slave cylinder are a maximum of 3 years old with both of the lines that run between the wheel cylinders on the rear end being less than a year.

The rubber lines up front were swapped two years ago as claimed by the previous owner. They are in excellent condition.

I'll be driving my 2 and 4 year old boys around in the truck, so I'm as anal about the braking system as anyone would be.

I do appreciate you looking out though. It is sound advice!

Brian