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Brake problem on a 1985 Chevy G30

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New User

Jun 14, 2013, 10:29 AM

Post #1 of 3 (2235 views)
Brake problem on a 1985 Chevy G30 Sign In

I have a problem with a 1985 Chevy G30 dual wheel box van with the hydroboost system.
This truck has over 200,000 miles on it.

The brakes are locking up from time to time and also are also 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.

(This post was edited by Discretesignals on Jun 14, 2013, 7:33 PM)

Ultimate Carjunky / Moderator
Discretesignals profile image

Jun 14, 2013, 7:39 PM

Post #2 of 3 (2208 views)
Re: Brake problem on a 1985 Chevy G30 Sign In

You should inspect the rears and make sure you don't have wheel cylinders or axle seals leaking all over the shoes. Also inspect the hardware
and be sure the wheel cylinders haven't froze if they aren't leaking.

If a front doesn't release the brakes when you loosen a caliper bleeder, you have some caliper pistons hanging up.

Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Jun 14, 2013, 7:39 PM)

Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jun 14, 2013, 8:52 PM

Post #3 of 3 (2193 views)
Re: Brake problem on a 1985 Chevy G30 Sign In

Just some thoughts on this to add: Can you get all wheels off ground all at once with what you have? If both sides on an axle I find that rare OR if this has been dunked in deep water calipers will almost always just fail as dust boots for pistons don't like that or time either but usually noticed one wheel at a time.

Have fronts been worn down low enough for pistons to go a bit crooked in all the miles? They can, HD such as this rotors could have been turned a couple times, thinner of course and can't take worn pads to the end.

Not yet even heard of hydro-boost or proportioning valve doing this and by releasing pressure at bleeders not changing it kinda rules those out IMO.

Other is even at a glance pads may look fine but separating from metal backing plate with wild odd behaviour till one at a time can fall right out. Some don't take long to do that,


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