Hi, I have a 95 Chevy Blazer that had a brake line going to the back of the truck rust out. In the process, the brake warning light came on. I replace the brake line running to back of the truck, the distribution block at the rear axle, and the lines running to the wheel cylinders. I ended up replacing the rear wheel cylinders because the bleeders were rusted in. I bleed the rear brakes. No air appears to be coming out of the bleeders any more. The brake pedal is firm but lower than before, but the brake warning light is still on and I have no rear brake pressure. Is it possible that the combination valve is stuck or frozen? Could I still have air in the rear brake system?
On Tue, 27 Oct 2009 19:16:10 -0700 (PDT), zwic...@frontiernet.net wrote:
>Hi, I have a 95 Chevy Blazer that had a brake line going to the back >of the truck rust out. In the process, the brake warning light came >on. I replace the brake line running to back of the truck, the >distribution block at the rear axle, and the lines running to the >wheel cylinders. I ended up replacing the rear wheel cylinders because >the bleeders were rusted in. I bleed the rear brakes. No air appears >to be coming out of the bleeders any more. The brake pedal is firm but >lower than before, but the brake warning light is still on and I have >no rear brake pressure. Is it possible that the combination valve is >stuck or frozen? Could I still have air in the rear brake system?
Does it have ABS? If so it may be one of those systems that can only be properly bleed by hooking up a computer to it to make the ABS valves open up and purge air.
On Oct 27, 11:03 pm, Ashton Crusher <d...@moore.net> wrote:
> Does it have ABS? If so it may be one of those systems that can only > be properly bleed by hooking up a computer to it to make the ABS > valves open up and purge air.
> On Tue, 27 Oct 2009 19:16:10 -0700 (PDT), zwic...@frontiernet.net > wrote:
> >Hi, I have a 95 Chevy Blazer that had a brake line going to the back > >of the truck rust out. In the process, the brake warning light came > >on. I replace the brake line running to back of the truck, the > >distribution block at the rear axle, and the lines running to the > >wheel cylinders. I ended up replacing the rear wheel cylinders because > >the bleeders were rusted in. I bleed the rear brakes. No air appears > >to be coming out of the bleeders any more. The brake pedal is firm but > >lower than before, but the brake warning light is still on and I have > >no rear brake pressure. Is it possible that the combination valve is > >stuck or frozen? Could I still have air in the rear brake system?
> Does it have ABS? If so it may be one of those systems that can only > be properly bleed by hooking up a computer to it to make the ABS > valves open up and purge air.
Yes, vehicle has K-H 4WAL ABS system, I do not believe that air was introduced upstream into the ABS system.
zwic...@frontiernet.net wrote: > Hi, I have a 95 Chevy Blazer that had a brake line going to the back > of the truck rust out. In the process, the brake warning light came > on. I replace the brake line running to back of the truck, the > distribution block at the rear axle, and the lines running to the > wheel cylinders. I ended up replacing the rear wheel cylinders because > the bleeders were rusted in. I bleed the rear brakes. No air appears > to be coming out of the bleeders any more. The brake pedal is firm but > lower than before, but the brake warning light is still on and I have > no rear brake pressure. Is it possible that the combination valve is > stuck or frozen? Could I still have air in the rear brake system?
If it is the combo valve, you can usually untrip the switch by pumping it up, holding it down 'hard' and opening a front bleeder. This makes the combo valve trip towards the front usually opening up the back for use and another bleed to get the rest of the air out.
Mike 2000 Cherokee Sport 86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00 'New' frame and everything else in '09. Some Canadian Bush Trip and Build Photos: http://mikeromainjeeptrips.shutterfly.com
On Oct 27, 10:16 pm, zwic...@frontiernet.net wrote:
> Hi, I have a 95 Chevy Blazer that had a brake line going to the back > of the truck rust out. In the process, the brake warning light came > on. I replace the brake line running to back of the truck, the > distribution block at the rear axle, and the lines running to the > wheel cylinders. I ended up replacing the rear wheel cylinders because > the bleeders were rusted in. I bleed the rear brakes. No air appears > to be coming out of the bleeders any more. The brake pedal is firm but > lower than before, but the brake warning light is still on and I have > no rear brake pressure. Is it possible that the combination valve is > stuck or frozen? Could I still have air in the rear brake system?
I remember someone telling that when you bleed the brakes with ABS just let the brake pedal go down until the brake light goes out.
zwic...@frontiernet.net wrote: > On Oct 27, 11:03 pm, Ashton Crusher <d...@moore.net> wrote: >> On Tue, 27 Oct 2009 19:16:10 -0700 (PDT), zwic...@frontiernet.net >> wrote:
>>> Hi, I have a 95 Chevy Blazer that had a brake line going to the back >>> of the truck rust out. In the process, the brake warning light came >>> on. I replace the brake line running to back of the truck, the >>> distribution block at the rear axle, and the lines running to the >>> wheel cylinders. I ended up replacing the rear wheel cylinders because >>> the bleeders were rusted in. I bleed the rear brakes. No air appears >>> to be coming out of the bleeders any more. The brake pedal is firm but >>> lower than before, but the brake warning light is still on and I have >>> no rear brake pressure. Is it possible that the combination valve is >>> stuck or frozen? Could I still have air in the rear brake system? >> Does it have ABS? If so it may be one of those systems that can only >> be properly bleed by hooking up a computer to it to make the ABS >> valves open up and purge air.
> Yes, vehicle has K-H 4WAL ABS system, I do not believe that air was > introduced upstream into the ABS system.
If the line broke and you lost all the fluid air got into the system. And you do need a scan tool to cycle the ABS system during bleeding.
Problem solved. I bleed more air out of the rear brake lines using a pressure bleeder setup instead of manual pumping of the brake pedal. I also readjusted the brake shoes tighter after fixing the seized brake shoe adjusters. I had rear brakes then but the brake warning light was still on. I had an assistant sit in the truck and push down on firmly in the brake pedal while tapping on the side of the combination valve. No change. I started the engine and repeated. The brake warning light finally went off due to the extra brake pressure from the vacuum power brake booster.
>due to the extra brake pressure from the vacuum power > brake booster.
Power brake boosters do not change pressure. The light went out do to the air being out of the system and the ABS solenoids cycled/set when you turned the key on.
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