Re: '01 2500 HD spongy brake pedal
Hatzie, thanks for the reply.
To answer your questions:
The master cylinder was bench bled. It took about an hour but all air bubbles were out before mounting.
New A/C Delco OEM power steering pump and A/C Delco power steering fluid. Hydro boost unit was used but I flushed it before installing. My original Hydro boost unit was leaking so I figured I would replace it.
I am running 17" tires. Over all diameter of 31". Standard width tire on GM 8 lug aluminum alloy rims from a later GMC truck.
For bleeding I made a special cap with an air fitting that snaps onto the master cylinder. I pressurize the master cylinder with about 5-10 psi from a compressor to push the fluid through the system. This works quite well as I can go from wheel to wheel and bleed the entire system while monitoring the level of fluid in the master cylinder.
When I bought the truck about 5 years ago, I replaced the hard lines with stainless steel ones since the originals were rotted out. All new rubber lines on 4 corners and rebuilt caliper on the corners as well.
Since the system was opened to replace the hard lines, I figured I must have gotten air into the system, or at least the ABS unit. So I bought a scan tool to actuate the ABS unit while bleeding. I have bled multiple times but with same result.
Peculiar thing: If the ABS is activated while driving on ice or something slippery, the pedal will firm up momentarily and then return to it's spongy state.
__________________
John
1967 C20 2WD Longbed
2001 2500 HD 4X4 Extended cab long bed
Last edited by Mickeymotormount; 12-18-2021 at 09:38 AM.
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