Question about sticking caliper on '86 C20

[fawkes]

Hello everyone. I have an 86 C20 that usually runs and drives great but today on my way to our campsite the passenger side front brake caliper started dragging really bad, and the truck almost pulled me off the road. But it's only the passenger side front caliper that's hanging up. I haven't had a chance to look into yet, but any suggestions on where to begin? It's not "locked up" but it's not releasing pressure and dragging really bad. Also something to note, the master cylinder was seeping some fluid out from under the lid and "twisting" when we pressed the brake pedal, I'm not sure if excessive pressure was to blame or not, but if it comes to that, can I use the original booster and just replace the master cylinder without issue?

Thanks for any feed back!

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[zieg85]

If the front brake hoses are original that may be the culprit

[bd]

Inspect the caliper for excessive mud and/or rust accumulation.  Check the condition of the brake pads.  Inspect the caliper slides for free movement.  Check the caliper brake hoses - if the right hose collapsed internally or developed a "flapper" it will restrict the flow of fluid to and from the caliper and can prevent a caliper from releasing.  Heed Zieg's advice.  If the caliper hose anchor appears severely rusted, just replace the hose.  Have the brake fluid tested for contaminates.

What do you mean the master cylinder was "twisting" with brake application?  If the entire booster/cylinder assembly is flexing on the firewall, inspect the firewall sheetmetal for starburst and radial cracks emanating from the booster mounting bolts.  If the master cylinder is seeping around the piston pushrod end as well as from the cap, the booster may contain brake fluid and should be replaced.  If the M/C cover gasket is distorted, checking for fluid contamination becomes crucial.

[fawkes]

Inspect the caliper for excessive mud and/or rust accumulation.  Check the condition of the brake pads.  Inspect the caliper slides for free movement.  Check the caliper brake hoses - if the right hose collapsed internally or developed a "flapper" it will restrict the flow of fluid to and from the caliper and can prevent a caliper from releasing.  Heed Zieg's advice.  If the caliper hose anchor appears severely rusted, just replace the hose.  Have the brake fluid tested for contaminates.

What do you mean the master cylinder was "twisting" with brake application?  If the entire booster/cylinder assembly is flexing on the firewall, inspect the firewall sheetmetal for starburst and radial cracks emanating from the booster mounting bolts.  If the master cylinder is seeping around the piston pushrod end as well as from the cap, the booster may contain brake fluid and should be replaced.  If the M/C cover gasket is distorted, checking for fluid contamination becomes crucial.

Thanks for the responses. The master cylinder (not the booster) was very slightly flexing to the side when we were pressing the brake pedal and it was causing fluid to seep out from under the cover, my guess is excessive pressure since the right side caliper seems to be holding fluid, causing it to not release. We cracked the bleeder screw loose to release the pressure and I drove it home fine. I'm just going to replace the pads, front lines, and that caliper and go from there. The parts are cheap so I'll just go a part at a time until I find the culprit.

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[bd]

The M/C shouldn't flex... certainly not enough to trigger a fluid leak, no matter how slight.  Make sure the M/C is properly mounted and suitably tight to the booster.

[Irish_Alley]

by the sounds of it it sounds like it was your hose. the metal bracket that bolts to the upper control arm will rust and squeeze the hose. it will allow fluid in but slowly release it