73-87chevytrucks.com

73-87 Chevy _ GMC Trucks => Brakes, Frame, Steering & Suspension => Brakes and Braking Systems => Topic started by: allanbegg on July 31, 2009, 12:06:32 pm

Title: No rear brakes
Post by: allanbegg on July 31, 2009, 12:06:32 pm

All,

We've stumbled across a problem and need some assistance. We aren't getting any brake fluid to either of the rear wheels on the project '78 K10. We had replaced a wheel cylinder on one side and when we went to bleed the brakes, couldn't get fluid to come to the cylinder. We opened the bleeder valve on the other rear wheel and found that there wasn't any fluid on that side either.

When pushing on the brake pedal, there is plenty of resistance, even with either of the rear bleeders open. The fluid level does not go down, in the rear reservoir, either.

What could be causing this?
Is the Master cylinder bad?
Could it be the proportioning valve?

Any troubleshooting ideas would be welcome.

Thanks, Allan

Title: Re: No rear brakes
Post by: ron350 on July 31, 2009, 12:36:52 pm

Sounds like you need to change the rear rubber brake hose that feeds the brake lines on the rear end.

The rubber swells shut and will not let fluid pass.

Title: Re: No rear brakes
Post by: VileZambonie on July 31, 2009, 04:06:23 pm

Open the system before the hose and see if there's fluid and work your way up.

Title: Re: No rear brakes
Post by: choptop on July 31, 2009, 04:24:26 pm

one problem that I have had very often is that the bleeder gets clogged up. Pull the bleeder out completely and make sure its not clogged up.

Title: Re: No rear brakes
Post by: joesgarage71 on July 31, 2009, 07:55:24 pm

 Don't your prop valve have a button deal on the front? If its sticking out push it in and try bleeding it. might as well bleed the front too. Using a small drill bit clean the debris from inside the bleeder screws first.
 Steve

Title: Re: No rear brakes
Post by: 4x4x4x on August 02, 2009, 09:40:47 pm

had a similar problem with my 85 k10 and it was a bad master cylinder. as a safety feature the master cylinder is designed so that in the event of rear brake problems, a valve in the master cylinder rear reservior that shuts off the the back brakes and you just operate off of the front brakes only.  we found this out after we had SS disk brake conversion done to the rear brakes.

replacing the master cylinder solved the problem.

Title: Re: No rear brakes
Post by: Irish_Alley on August 03, 2009, 12:21:16 am

it does should like a master cylinder problem but i would check the lines like vile said. start with were the rear line "y"s off take the line off before the y and see what you have then go to the other end of the rear rubber then move up to the proportioner (think thats the right spelling) valve see what you have there try after the valve then before if still nothing then it your master cylinder better yet try that first if you get any start at the rear and work to the front