Packard Forum Index » Post-War (1946-54)

Hi guys. I am new to this forum and have been reading and digesting all the posts and information I can in the past few months, Thanks for all the info.

I have been restoring a 1953 Packard Clipper 2 door coupe for the past few months. The car was in very nice condition and engine had been rebuilt not to long ago.

Now complete and driving, I have come across an issue with the power brakes. Prior to the restoration the brakes worked beautiful so the only items I replaced were the brake lines and vacuum lines. When I go to start the engine the brake pedal engages the brakes by itself without me applying my foot to the pedal. When I remove vacuum line to booster and plug line all works manually perfect. When car is turned off brakes feel normal.

Thanks in advanced for any help someone might have for this problem.

I woud check the pedal and rod alignment first. If there is anything binding or out of alignment so the pedal can't retract fully when your foot is off then it might be activating the vacuum section. With the engine running so there is vacuum grab hold of the pedal and try to pull it back. If it moves at all and the problem goes away then check the carpet or that the screws on the floor plate are not loose or missing so the floor plate slipped or the rod is not at an angle between the pedal and brake unit. Less likely but has happened is the pedal bracket on firewall has developed some kind of bind.

If that doesn't seem to be the problem then something has happened internally like maybe a broken spring or failed valve or diaphragm.

EDIT: The 53 unit should only have the one hose connection on the side. Confirm that is correct and an earlier unit with two hoses hasn't been installed. If it does have two hoses make sure the vacuum supply is on the upper connection.

Yup to all howard said. You mentioned replacing the brake lines so you must have been pumping the heck out of the pedal to bleed unless you used a hand vac or pressure bleeder. You did not say if you replaced hard lines fr n rr and the rubber flex hoses. Best way to diag this is on a lift or jackstands with all 4 up. Engine off, spin all 4. If free start engine just for a few seconds or ensure proper ventilation and try to spin all 4. If they all have drag or are locked- pull up on the pedal and have a friend spin en. If all are free problem is in the vac booster. You can use this method to find bad hoses and pulls on apply and drag on a specific wheel after release.

G'day calgt,
to PackardInfo. And I invite you to include your '53 Clipper Coupe in the Packard Owner's Registry.

Thank you for the information. Last night I checked the carpet, boot, etc. Everything looks great. I did replace all hard lines, rubber hoses, etc when restoring the brake system. The booster only has one vacuum line. Used a preasure bleeder to bleed the brake, so no hard use of the pedal. All wheels and brakes are working correctly. I think I will need to remove booster, inspect and rebuild to see if that is the problem. Thanks again for all of your time.