Packard Forum Index » Pre-War (1899-1942)

I recently installed a new master cylinder, wheel cylinders, hoses, shoes, etc on my 1807 Formal Sedan. The car stops on a dime now BUT, when I start depressing the brake pedal to slow the car down, the motor also slows down. If I continue to push the pedal, the car will very quickly stall.

This sounds to me like a vacuum leak tied to the brakes.


Does this car have a vacuum brake assist? If so, where is it?

Any other thoughts on what could be the issue?

Thanks,
Gar

Power-assisted brakes, vacuum or otherwise, were not offered in 1940.

Is the clutch releasing properly when you depress it to start slowing down to a stop or is the problem just in slowing down a slight amount but the car is still moving fast enough the engine is not going to want to stall because of car speed.

Can you put the car in neutral and move the accelerator to get the engine at a decent rpm and then quickly let off the accelerator. Does the engine want to die when the throttle closes. If so, some of the 40s had a vacuum operated dash pot like device to sort of control the speed the throttle closed so engines would not die as the air was abruptly cut off. If yours has one maybe it is not working.

The clutch releases and shifts into neutral and the motor slows down very slowly without an issue, as long as I stay off of the brake.

I can rev the motor up and completely take my foot off of the accelerator and the car's rpm will slow down but it doesn't stall. If I do the exact same thing and push the brake pedal, the car will stall.

Very strange.

I read about the dashpot in the owners manual which is supposed to be an anti-stalling device on the carb. I will check it out and see if I have a leak or if it is not functioning correctly. The brakes are totally not connected to to anything so I don't know why that would be causing me an issue. Maybe just coincidence...

Any chance the brake pedal is rubbing or moving a wire when it is pushed down. If the engine abruptly stalls and the car has OD perhaps somewhere the ign cut out circuit is being prematurely grounded. Does the car have the armored cable between the coil and ign switch. If so is that cable being moved by the pedal or anything else. The wire inside the armored cable has been known to act up when moved.

Shorting a wire... I never thought of that. Great suggestion. I will check it out this week and let you know.

The ignition cut-out circuit runs down from the OD relay and over to the rear side of the distributor. If it isn't fastened up to the trunk of the wiring harness, it could be hanging in front of the brake arm. The master cylinder is in the area, so perhaps the wire was moved from where it was to finish installing it.

If anything the throttle guard would apply more gas, not stall you out. Says one who has not yet tested the throttle guard he installed this am.

Good afternoon all...I wonder if this problem could be connected to the carburetor float or needle valve? Ernie in Arizona

One other humble thought...the other day 'Miss Prudence' was stumbling a bit and I found two things. The positive battery terminal had worked loose and there was a bit of junk in the carburetor filter! The old girl just wanted me to pay a bit more attention to her! Ernie in Arizona

Just wanted to do a quick follow up.

The stalling was was two fold:
CARB float was a bit too high (which caused the car to flood, when I would stop)
There was also a short in the wire to the coil.

THANKS for all of the help!