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| | | | Joined: Dec 2004 Posts: 1,897 Shop Shark | | Shop Shark Joined: Dec 2004 Posts: 1,897 | Installed on my 1959 gmc 1/2 ton for about 5 years. The pedal does not always return to the top. This is the under floor booster with combination valve on a disc/disc truck.
When I start the truck, I can see the pedal move about 1/2 way down, and then slowly come back up. Brake travel seems a bit much. I noticed a small drip of fluid coming from the booster last week.
So do I have a bad MC? (spent several hours bleeding the brakes today, the front reservoir was dry.)
A bad vacuum booster?
Or something else I haven't considered? | | | | | Joined: Dec 2004 Posts: 1,897 Shop Shark | | Shop Shark Joined: Dec 2004 Posts: 1,897 | Oh yeah, I suspect a broken spring in the front part of the MC which actuates the rear brakes. | | | | | Joined: May 2006 Posts: 8,351 'Bolter | | 'Bolter Joined: May 2006 Posts: 8,351 | Sounds like the seal at the pushrod and the seal in the booster are bad. If you check the hose to the manifold from the booster, it'll probably be wet with brake fluid.
Bill Burmeister
| | | | | Joined: Dec 2004 Posts: 1,897 Shop Shark | | Shop Shark Joined: Dec 2004 Posts: 1,897 | Thanks Bill
Under the rubber dust boot on the booster, there was a metal cap with a felt seal that had worked it's way off the booster. That cap was preventing the pedal from returning.
I believe the excessive brake travel is the adjustment rod between the booster and the MC. I believe this rod has walked in over time increasing the free pedal travel before the MC is actuated. | | |
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