Loss of power assist braking

[Joey]

Just thought that I would post a note to see if anyone out there has run acrost this problem. I have a 2000 Chev 2500 3/4 ton 6.0L with Hydro Boost brakes and they have failed. The poweer steering works fine but no assist on the brakes. I changed the Hydro Boast unit and they still do not work any ideas? My assumtion was that if the power steering works that the pump was not the problem and the fact that the two systems are in series that the issue would have been the Hydro Boost unit. I hate to think that I have spent $150.00 for nothing.

[Joey]

Just thought that I would post a note to see if anyone out there has run acrost this problem. I have a 2000 Chev 2500 3/4 ton 6.0L with Hydro Boost brakes and they have failed. The poweer steering works fine but no assist on the brakes. I changed the Hydro Boast unit and they still do not work any ideas? My assumtion was that if the power steering works that the pump was not the problem and the fact that the two systems are in series that the issue would have been the Hydro Boost unit. I hate to think that I have spent $150.00 for nothing.

[CD]

Joey
I can be wrong but I think you need to look for Vacuum loss. Any brake boost systems I have worked on used vacuum not hydraulic but that has been a while.

[RustyJC]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by CD:
Any brake boost systems I have worked on used vacuum not hydraulic but that has been a while. </div></BLOCKQUOTE>
If your brake system on your 2001 Cummins/Ram fails, you'll be exposed to hydro-boosted brakes. Since a diesel, having no throttle plate, doesn't produce engine vacuum, Dodge uses a hydro-boost system that uses pressure from the power steering pump to provide hydraulic assist for both the steering and brakes.

As to the original post, I'm not a GM mechanic, but I find it interesting that a 6.0 gas engine wouldn't use the traditional vacuum booster for the brakes since the vacuum source is already there.

Rusty

[Joey]

It is hydro boost with the unit getting its power source from the power stearing pump along with the PS unit. Bith units are in series as for as the flow of fluid from the pump thus being the reason that expected the hyrdo boost unit to be the problem as the PS works fine.

[Ray,IN]

Rusty- Dodge uses a power belt driven vacuum pump to power a brake vacuum booster. I received a recall notice on mine to have the check valve replaced.

[RustyJC]

Ray,

What year? The later 24 valve 2nd generation Cummins diesel like mine uses a vacuum pump on the back of the hydraulic pump. The steering and brakes are hydraulically assisted (hydro boost). The small amount of vacuum produced by the vacuum pump is only used for control functions such as the HVAC damper actuators, etc. The 3rd generation Cummins has no vacuum at all - to add an exhaust brake, Jacobs supplied a belt-driven vacuum pump as part of the kit.

Rusty

[Larry]

Ray must be referring to the same recall I had on my '96, to add a check valve in the vacuum system. My 2001 is hydroboost,built in 2/00. I thought they changed to hydroboost in '97 or '98.
Larry