Having problems with your 1983 Ford F 250 ?
My 83 f250 makes a air leak sound under the dash when the brake pedal is compressed and even when not. is it a bad master cylinder?
Sounds like the brake booster has a hole in the diaphragm .. You should be able to pick up a used one fairly cheap and they are easy to change out. You don't need to undo any brake lines just remove the master cylinder and prop it out of the way.
Repair Help & Product Troubleshooting for 1983 Ford F 250
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