First off I hope this is posted in correct spot , I'm using mobile app I have a 1963 mercury Monterey , power brakes with master cyl single outlet . Drove it this weekend and had no issues , when we got home and parked it brake lights stayed on , I then tried to move car and the pedal was solid as a rock and car wouldn't move , brakes were locked up , next day all was ok again . Any suggestions , I assume it's gotta be in the master cyl or vaccum booster . We replaced master cyl , metal lines , rubber hoses etc when putting car together . Also the brake light switch is mounted right on master cyl Posted using the Full Custom H.A.M.B. App!
two pretty common causes for that are the pushrod for the master cylinder adjusted too tight, and the brake hoses being old and collapsed.
I'm going with Jim's assessment,most likely the old rubber brake line hoses have gotten soft and collapsed. HRP
make sure there is a little bit of free play between the pedal and the booster. If not, adjust so there is and try it. If the pedal adjustment was good, then maybe there is an adjustment between the booster and master cylinder, that's too tight. The master cylinder piston needs to be able to return fully to the rear, or it blocks off the little bypass hole that lets fluid expand in the system when it heats up.
The pedal would not move at all it was solid as a rock , tried to push , and pull it , but the next morning worked perfect again Posted using the Full Custom H.A.M.B. App!
it's hard as a rock because of pressure in the system , re-read and follow the advice in post # 5 that little port in the master cylinder needs to be uncovered and clear for your brakes to work properly
Sounds like not enough play in the pedal - booster area. Pedal is pushing ever so lightly on the booster, leading to a slight pressure in the system, clue is the brake lights (pressure activated on this car) being on. Another clue is the pedal being rock hard, there should be a bit of free play. Last clue is that they were fine the next day - after the vacuum has bled off. Loosen the adjustment between pedal and booster. Cosmo
what they all said--more free play in rod-also how close is your exhaust to brake lines, etc. Symptoms should have caused the brakes to start dragging after driving it a while I would think.
A friend of mine drove his 64 Ford right after replacing the M/C and had the same problem, as said above, we all suspected pedal play but here was no adjustment! When we got home he stood on the brakes and it popped... Ford M/Cs use a clip on the end of the push rod that keeps the push rod in place when not mounted. When we heard the pop, he said what was that? I said you just fixed your problem. Sure enough the clip hadn't seated and the factory rod with no adjustment was too long until it got seated on the rod. It was and is fine after that. Your Mercury probably has the same M/C setup. We used washers to space the M/C away from the firewall to get it home. Once it went pop the spacers were no longer needed. The M/C piston, out of place won't allow brake fluid to return properly and brake line pressure builds up.
Power brake booster pedal rods generally attach directly to the pedal without any clearance adjustment because they are part of the booster control valve. The booster-to-master push rod, however, is often adjustable, and may be the problem, as others have previously stated. I don't have any '63 info, but pictures of '63/'64 boosters very look similar, and my '64 big Ford/Merc shop manual states the push rod length from the master cylinder mounting surface of the booster should be adjusted for .995"-1.005". To verify, look closely at the rear fill port inside the master as you slowly install it on the booster, making sure the piston does not move as you secure the master. Ideally, the push rod should just touch the master cylinder piston, but no more than .015" clearance. Although the manual doesn't say, I would make this measurement with full engine vacuum in the booster, or about 20" Hg. Another thing that may be needed is a separate pedal return spring to assist the booster returning the pedal fully.
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