Chevy & GMC Vans

Had Green's pedal hit the floor while out for lunch today, then it was fine the rest of the day. Once I returned home, I was able to repeat the pedal to floor by pressing the brakes really hard. I tried bleeding the brakes to fix it, but I was still able to hit the floor with enough force.

I don't see any leaks in the lines or master cylinder.

I'm suspecting the master cylinder, but I've never had one wear out before.

What do you all think?

+1 on the master cylinder

I had that happen twice, once with leaky line by gas tank. Other was the driver side line rusted out.. That one was hard to find at first, but once you found the leak it was real obvious.. Checkon the level of the fluid after a few pumps, maybe its just a leaky line and a cheap fix.

Scott

Yep. You got master cylinder issues. I had one fail AFTER I had Firestone do a COMPLETE brake job. The mech said that masters rarely go bad. BS! When I pulled that one out, there was a pit in the cylinder wall big enough to hide a VW in.

Make sure you bleed the replacement master BEFORE you install it in your beastie.

Pulled Green's master cylinder yesterday and took it apart. Yuck, dirtier inside than I thought it would be. Will finish cleaning it after work, then put it back together. Hopefully a good cleaning is all it needs.

Aaron,

It's kind of tough to figure out if it is a master cylinder or the hydro booster.If you truly go right to the floor with it I suggest it would be the master and search for the link that Darren put up to bleed the whole brake system to replace the old dirty fluid,but if it goes to a hard spot which appears to be the floor and then you rev up the engine right after that and it goes back to normal,then it's the hydro booster.

Oh,btw Aaron-if you have ever put in brake fluid in the power steering system,the two fluids are very different and it will screw up how the power booster acts.I found that out the hard way.Yeah-this old school boy is still learning.

I know it's not the hydro boost.

Had the pump go bad on my 2000, 6 hours from home in a winter snow storm. Was on a MTB trip as part of a four car convoy. Was fun driving back loaded with guys and gear without the power steering or brakes. Pedal never hit floor though.

Grumpy's pump is weak and I can feel the difference in pedal at low RPMs, yet I can never hit floor no matter how hard I try.

I am sure you have done it but check those lines to the back end - a little rusty leak and somehow not presenting itself on the ground and you've found you problem. However I am sure you have killed that idea by now, and your probably right the master cylinder is the issue. Keep us posted. Man now that I sold the Van and got the Expy I miss this place - the knowledge base is unmatched! Keep it up guys/gals!

Yeah I know this sounds kind of hokey,but the rear brake lines on the 1994 are run threw the open part of loop's part of the gas tank straps.The open part of it on the bottom by the strap bolts.I bought it that way and no more of the hidden brake line above the gas tank.

Well, this is still driving me nuts. New master cylinder installed, properly bench bled. Brakes bleed several times. No leaks to be seen anywhere. Soft lines do not swell.

When the van isn't running the brakes feel great, nice and solid, unable to push the pedal to the floor no matter how hard I try. Start the van up, with effort I can get the pedal to the floor. Driving around the pedal feels good, but twice today while maneuvering in a parking lot the pedal found the floor. Could the hydroboost have something to do with it?

CaptSquid wrote:Yep. You got master cylinder issues. I had one fail AFTER I had Firestone do a COMPLETE brake job. The mech said that masters rarely go bad. BS! When I pulled that one out, there was a pit in the cylinder wall big enough to hide a VW in.

Make sure you bleed the replacement master BEFORE you install it in your beastie.

Wow, a VW! Was that an old or new beetle??!!!

Drive safe,

Dan Harriman
91 Safari Shorty V8 RIP
Orange Texas

It's not likely the hydro boost. Pressure bleed the system. It sounds like there's air trapped in there somewhere.

Sounds like it's time to buy more tools.

Anyone with suggestions for a good kit?

Somewhere on this site Darren posted "how to" on building a pressure bleeder from a small garden sprayer. I took the idea and ran with it. It works great. Only invested about $20.

Smiliesafari wrote:Somewhere on this site Darren posted "how to" on building a pressure bleeder from a small garden sprayer. I took the idea and ran with it. It works great. Only invested about $20.

Any pics of yours?