1978 Chrysler makes hiss sound and brakes seem soft when applying brakes
- Thread starter Fred A
- Start date
As in hard to stop soft, or too much travel? The hiss from under the dash at steering column is usually followed by a booster failure. You can have a bad brake master cylinder that has leaked fluid into booster and booth are on the way out.
Chk fluid in gthe master cyl and also look for a brake fluid trail from the middle of where the master cyl mounts to the booster.
The hiss is from vacuum, it can progress to where the engine misses when you step on the brakes, too. Plan on a rebuild of the booster, at least.
CBODY67
The hiss is from vacuum, it can progress to where the engine misses when you step on the brakes, too. Plan on a rebuild of the booster, at least.
CBODY67
To much travel. It stops good but close to floor
Have checked the rear brake shoe adjustment, front pad wear?
hootothecore
New Member
Does this car have the vacuum actuated automatic parking brake release when putting car in drive or reverse?
Darter6
Active Member
If I remember Chrysler had a recall because of complaints of the hiss sound. I worked at a Dodge dealership mid 70's back then.
Now this was over 50 years ago and my memory isn't the best. I believe there was a filter/silencer that was inserted where the brake pushrod went thru the firewall. Not much to it a fiber/fuzzy disc. I was the carb/tune guy and seldom did brake warranty work.
Maybe some one else remembers....
Now this was over 50 years ago and my memory isn't the best. I believe there was a filter/silencer that was inserted where the brake pushrod went thru the firewall. Not much to it a fiber/fuzzy disc. I was the carb/tune guy and seldom did brake warranty work.
Maybe some one else remembers....
First off, apologies for the pics from under the dash of my 78 NYB...I'm not a flexible as I used to be.
Start the car and stick your head under the dash and locate the source. Look in the following 3 places:
Your NYB has a feature that automatically releases the parking brake when you move the shifter...it is vacuum operated.
This pic is of the vacuum actuator on your emergency brake...the silver can in the pic...the hose runs to the top of it not in the picture:
The vacuum switch at the base of the steering column (with the 2 vacuum lines to it):
The last place is the cylindrical bellows (vacuum booster) visible behind the vacuum lines.
These are the likely sources of your hissing noise. If it is the Ebrake system, you can just block off the offending leaky part until you locate replacement parts, or leave it as there is a manual brake release back up.
If it's the booster, obviously, it will need to be replaced.
Start the car and stick your head under the dash and locate the source. Look in the following 3 places:
Your NYB has a feature that automatically releases the parking brake when you move the shifter...it is vacuum operated.
This pic is of the vacuum actuator on your emergency brake...the silver can in the pic...the hose runs to the top of it not in the picture:
The vacuum switch at the base of the steering column (with the 2 vacuum lines to it):
The last place is the cylindrical bellows (vacuum booster) visible behind the vacuum lines.
These are the likely sources of your hissing noise. If it is the Ebrake system, you can just block off the offending leaky part until you locate replacement parts, or leave it as there is a manual brake release back up.
If it's the booster, obviously, it will need to be replaced.
Rick T
Member
My 78 does the same thing when it’s cold however it has a built 440 with a heavy cam. I believe that’s what’s causing my issue once it’s warmed up it doesn’t do it anymore. I’m assuming low vacuum, but it doesn’t do it all the time.
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