The Stovebolt Site Forums The Parking Lot Big Bolts Brake bleeding

After honing out all 6 wheel cylinders last year and installing new kits, I still lost 2 cylinders. We bled them many times before going for wood, but I lost a rear one half way back. I crimped of the rear flex line, then lost a front seal just after I got home. This is on my '53 Chevy 2 ton.

A mechanic says I need to bench bleed the cylinders. First question, would it not be easier to plumb in a bleeder valve at the highest point on the bracket? 2nd; Are my pads shot now that they have been soaked in brake fluid? I sent them out to have religned last year.

Something sounds wrong, either bad seals, or the cylinders were to far gone even with honing. They could be to much oversize to seal properly, or pitted or scratched?

It would not hurt to bench bleed the cylinders, although I have never heard of it being done for wheel cylinders, just new master cylinders. If you had all the air out and a good firm pedal the way you first did it you can't ask for more.

You already have a bleeder valve at the highest points of the wheel cylinders, there is no need for additional bleeders.

Brake shoes are ruined by brake fluid, or at least they don't work very well after.
There are many "tricks" to get the brake fluid off, but the problem is it is soaked in the pads, and with heat from braking it resurfaces.
So, all the brakeclean in the world won't fix it.

I have heard, but have not tried, that if you soak the pads in Coleman fuel, (white gas) then set them in a shallow pan with a little more fuel, then light it you can burn most or all of the brake fluid out. I would give it a try, as you have nothing to loose. I think it may work satisfactorily, but again, have not tried.

Grigg

Grigg, I asked my friend who did the wheel cylinders for me if he mic'd the wheel cylinders before he got the kits. He said they weren't pitted much so he honed them out and just put the kits in. Now I'm not even sure he took the numbers off the cylinders and bought the correct ones. He had repair shop in the Bay area for 20 years, but I haven't been impressed with his work so far. Guess I had better do them myself this time.

I'll let you know how the brake burning works. If I singe off my eyebrows I'm blaming you!

If your brake drums are to big, in other words turned to far, your brake shoes will expaned to far and the cylinders will leak or come apart

101053, Good point. That's something I should have thought about, again I trusted someone else to take care of the brakes.

Grigg, on another thread, I saw something about bleeding the hydrovac. Should that be done whenever the whole system (all wheel cylinders) are bled too?

I believe that the hydrovacs have a bleeder screw, but honestly I have never messed with one, only to remove them and install hydroboosters.

I would guess that yes you should bleed it.
I'll have to refer you to the shop manual for the details.

Grigg

Hey, Grigg, me again, about Hydro-Vacs this time.

The 1987 Suburban 3/4 ton Diesel has Hydro-Vac. (My wife checks it every morning to make sure it hasn't moved to the 1951.) I've never liked the feel of those brakes, but they sure do stop.

The system has drum brakes front and rear, and the rear shoes were installed by a GM certified mechanic. Unfortunately, he is my step son, so I have my suspicions.

Anyway, the thing that bothers me is that there are a few degrees of free play in the pedal and then it acts like the brake drums are not round. The pedal doesn't move, but the stopping action is kind of 'lumpy' for want of a better word. Its been like that ever since we've had it.

I'm 90% sure that this is not a Hydro-Vac issue, but you've driven ones that actually work. Have you ever run into anything like this?

I also suspect that I might need to find out what the bleeding operation consists of. We think that the truck has 242,000 miles on it, with only a transmission re-build, but we aren't sure.

The PO said that he had hauled a 5000 pound boat back and forth to Florida, from St. Louis, MO, many times (one of the reasons I was daring enough to try to haul the 1 1/2 ton home with it, and it is probably also why it has that lace effect around the lower body.)

Starkweather,
First things first, a Hydro-Vac "sucks". A Hydrobooster uses pressure from a PS pump to help stop.

So, your suburban has a Hydrobooster right?

There is nothing different to do with the brake system when bleeding brakes with a hydrobooster.
When first starting after changing a PS pump, box, line, or hydrobooster you will need to follow some simple steps to work the air out of the pump, so as to not kill it when you start the engine. in short you jack up the front of the vehicle and turn the wheels full left to full right about two dozen times, engine not running. Then you start the engine for about 5 seconds and cut it off. Check and refill the fluid very frequently the entire time. Then with engine running turn left to right a bunch of times again, checking fluid often.

Nowadays Hydroboosters are not recommended for drum drum brakes, as they can be a little funny feeling.

Both of my trucks have disc disc brakes.
One has a 2004 booster and it works very nicely, smooth, consistent, and strong.
The other has a booster from the 80's. It feels about as you describe, I have no problem with it, but it is different.

Hydroboosters are essentially the same from the first ones to the ones used today. However there are many internal changes over the years that give the newer ones a more civilized feel.
Both ford and GM use almost the same boosters, the only difference is the MC bolt spacing and pilot bore.

So, sounds like your booster is normal, you could upgrade to a late model one if you wanted, but I would leave the Burb alone and put the late model one on your 4400.

For someone who really knows Hydroboosters talk to Paul at http://www.hydratechbraking.com/ He has helped me a bunch with my projects. I don't think there is a question about a hydrobooster he does not know the answer to.

Grigg