And my brake pedal went to the floor!

[four_by_ken]

Took out the M1008 last night to get something to eat. Got to the end of the street and the pedal went to the floor. Dummy brake light came on.

Truck is now a full double pump to stop. The brake light goes out after a second pump to build pressure.

Never had problems with brakes before.

Now, as I am typing this... as I checked the oil yesterday, I did notice a spot on the frame, under the master cylinder that was real wet with 'oil'. I thought I had a leaking valve cover or something. Maybe its was brake fluid?

 

[doghead]

Are your power steering fluid and brake fluid levels correct?

 

[four_by_ken]

Are your power steering fluid and brake fluid levels correct?

It was dark when this happened and I just parked it for the night. Had been working on things all day and I was burnt out for the day. I will have to look tonight when I get home.

 

[four_by_ken]

Brake fluid was definitely low. Time for a master change.

I was told there were two different master cylinders in '86 for a K30, diesel, 4wd. And that I had to look at the stamping on it to determine which one it was.

Well, the casting didnt match either one.... the stampings were not what they were 'supposed' to be.

But, it was easy to tell the correct one by the input to the master cylinder coming from the hydra boost.

Hopefully this will help someone else.

Brakes are back to normal now.

 

[Recovry4x4]

Steel lines are subject to rusting. Check them all thoroughly.

 

[four_by_ken]

Steel lines are subject to rusting. Check them all thoroughly.

Brakes are good now. It was the master for sure.

 

[doghead]

Could you post the part, brand name and part number here Please?

 

[four_by_ken]

Could you post the part, brand name and part number here Please?

When I go back outside next I will get the info and post it up.

 

[four_by_ken]

Here is the box of the correct master cylinder that I got. $19.99 from Murray's.

Perfect fit and the brakes are now working great again.

And here is the text, just in case my photobucket picture disappears.

CARDONE Online Home Page is the manufacturer.

part number 10-1584

 

[EZFEED]

Seems it would be a good measure to rip all the original lines out of a truck and replace with stainless. I had a case of rusted line twice

 

[four_by_ken]

Seems it would be a good measure to rip all the original lines out of a truck and replace with stainless. I had a case of rusted line twice

If it was a rusty truck, I would... but there isnt any rust on my truck.

 

[StrykerPez]

Hate that feeling. Both times it happened to me was in my 9000+ lb GMC 4x4. First time, the power steering line blew so I lost both steering and brakes at the same time. Then the drivers side soft brake line blew while I was going down a hill towards a red light and a bunch of stopped cars. Thankfully I managed to ditch into a parking lot and run over a planter without hitting anything.

You probably have a leaking rear seal on the M/C. Replace it soon!

 

[four_by_ken]

You probably have a leaking rear seal on the M/C. Replace it soon!

Nope, was definitely the master cylinder... as I said above.

 

[Crash_AF]

I'm having a brake problem with my 1009. When I got it, it didn't have a master cylinder on it (long story short, it was a residue truck) and I'm almost ready to put it on the road. I don't know how long the master was off, but I put a new one on and the brakes won't bleed. No matter how much I pump, I do not get any pedal pressure or pressure out of the wheel cyl/caliper bleeds.

I'm guessing I got a bum master cyl from the store, but does anyone have any other ideas before I go diving into the brake system?

Later,
Joe

 

[four_by_ken]

I'm having a brake problem with my 1009. When I got it, it didn't have a master cylinder on it (long story short, it was a residue truck) and I'm almost ready to put it on the road. I don't know how long the master was off, but I put a new one on and the brakes won't bleed. No matter how much I pump, I do not get any pedal pressure or pressure out of the wheel cyl/caliper bleeds.

I'm guessing I got a bum master cyl from the store, but does anyone have any other ideas before I go diving into the brake system?

Later,
Joe

Did you bleed the master, or just trying at the wheels. You HAVE to bleed at the master. Most new master cylinders come with a bleed kit. Basically two little plastic adapter that allow you to run a rubber hose from the front and rear reservoir outlets back into the reservoir itself. When that his hooked up... a dozen or so pumps and you are good to go. Without doing this (or a bench bleed, just mounting it is just as easy) you will never get a firm pedal.

 

[Crash_AF]

Yes, I installed it and then used the bleeder kit to get the air out. Then I put the lines on and tried to bleed it and got nothing at the wheels.

Later,
Joe

 

[four_by_ken]

Yes, I installed it and then used the bleeder kit to get the air out. Then I put the lines on and tried to bleed it and got nothing at the wheels.

Later,
Joe

Something is wrong for sure! I would fill the master and let it gravity bleed for a bit and see if you get some fluid to the calipers. If you bled the master with the little kit and it worked... meaning that the fluid did come up out of the hoses the kit came with... there is nothing wrong with the master. That leaves the calipers and lines.

Also, get one of the bleed pump kits they sell at the auto parts stores... much nicer than the old pedal pumping method.

 

[ChuckSmith]

Depending on how long the master was off, the lines are probably clogged with rust. Brake fluid absorbs moisture rapidly. No master on it allowed them to rust internally. I'd be replacing the lines. Stainless is a good idea, but you can also get the coated lines, they hold up well, they are cheaper than stainless, and are easier to work with (bend).

~Chuck