1973 GMC 6500 dump truck brake problems

[heavyd]

Bought this dump truck to use on my farm. Of course, it's not worth a squirt if the brakes don't work. It has the hydrovac system.

The issues are:
Won't hold a peddle
It's sucking air from I believe what's called the accumulator

I think it's the hydroboost because after I pump up the peddle, it won't drop and plunge back up when you crank the engine. I've bleed the system several times, so it's not air in the brakes.

Any ideas or advice? I can't sink too much in this old truck, but I'de be happy to pay someone who is a professional for some advice. Thanks, guys.

 

[Kahrnut]

Did you drive it home? Does it have standard, or air brakes? Does it have a power brake booster? Pics?

 

[bambam]

What does the computer code read?

 

[heavyd]

It's hydroboost. Regular brakes with hydraulic assist from the power steering pump.

 

[heavyd]

What does the computer code read?

Hahaha

 

[bambam]

The bladder may be out in the booster.

 

[bambam]

Here is a good old Army training film for you.

 

[jeep78]

Do you have a diesel engine?

Are there 2 hydraulic hoses coming from the power steering pump to the brake booster?

Do you have air brakes?

Can you post a pic of the brake master cylinder together with the booster it attaches to?

 

[Kahrnut]

The bladder may be out in the booster.

That's what SHE said!

 

[heavyd]

It does not have air brakes. Gas engine. High top 427.