# Brake Problems:1985 Chevy G30 van with hydroboost system



## CHETT (Mar 4, 2011)

*I have a problem with a 1985 Chevy G30 van with the hydroboost system.*
The brakes are locking up from time to time and also are grabby at times. I know that the front brakes are locking up but I am not sure yet about the rears. 
If I let it set for a while the pressure bleeds of and they may be OK for a week or more. I have bled the front brakes to remove any dirt. 
Opening the bleeders does not to seem to instantly release the brakes either. The brake pedal does not seem to be sticking and the actuating rod length has never been changed.
I have been told the master cylinder will not cause this. What about the hydro booster or proportioning valve? 
The brake system warning light DOES NOT come on when this happens.
I am desperate here as this is the truck I use to make my living as a contractor.
if anyone has experienced this please contact me.


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## Wrench97 (May 10, 2008)

If you open the bleeder screw is there pressure at the calipers without the pedal being pressed? 

There could be several reasons a blocked hyd return line from the hydro boost to the power steering pump being one, a failing hyrdo booster another.


If brake pedal is free of any binding conditions and return line is free of obstructions, remove the master cylinder cover. 
Observe the brake fluid in the reservoir while rapidly depressing the brake pedal one inch. 
Fluid surface should have some movement or spout in the forward reservoir section. Minor spouting may occur in the rearward reservoir. If no movement or spouting of fluid occurs in the forward reservoir, the hydro-boost unit is defective and must be replaced.


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## CHETT (Mar 4, 2011)

Wrench97 
If I carefully probe the return booster line with a wire to check for blockage is there any chance of damaging anything in the power steering pump? Would it be practical to attempt applying vacuum or low pressure air to it when it is not running?


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## Wrench97 (May 10, 2008)

Problem is sometimes the inner liner in the hose cracks and the fluid flowing through it causes it to flap up like a valve and close off(the same thing can happen to a brake hose), a wire probably won't find it, air may but I would disconnect both ends of the hose before trying it.


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## CHETT (Mar 4, 2011)

When I tore the system apart I saw that the brake booster was leaking internally. I installed a rebuilt brake booster two weeks ago and it seems to have resolved the problem. Thank you for your help.
Chett


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## Wrench97 (May 10, 2008)

Good to hear you found the problem


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## wolfen1086 (Oct 4, 2007)

Good to hear


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## CHETT (Mar 4, 2011)

CHETT said:


> When I tore the system apart I saw that the brake booster was leaking internally. I installed a rebuilt brake booster two weeks ago and it seems to have resolved the problem. Thank you for your help.
> Chett


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## CHETT (Mar 4, 2011)

Please read to end and help if you can.
Well friends after a few months now I have replaced the hydroboost unit 3 times only to have the same problem return in time. All came from A1 Cardone the worst rebuilers in the world and apparently the only ones too.
I have had many of their products fail before.
*HOWEVER* I am wondering if possibly there may be an adjustment rod somewhere in the system that needs addressed??!! 
Could the a linkage be keeping a slight pressure on the spool valve and not letting it return all the way to purge the pressure after repeated applications of the brakes? 
As before if I let it set or crack all the line fittings the brakes release. 
I also changed all the hoses and the pump and flushed the system power steering to make sure it is not a contamination problem with the last replacement. 
Chett


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## Wrench97 (May 10, 2008)

There is a rod coming off the brake pedal that should be adjustable, however if there is a little bit of play(as in you can pull the pedal back towards the seat a fraction of an inch and it drops back) that won't be the problem.

If you crack the 2 lines coming off the master cylinder when this happens do the brakes release?


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## Panther063 (Jul 13, 2009)

The Brake Master Cylinder may be sticking on, rust or sludge build up internally can cause this.


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