bam_bam
New Member
- Joined
- Aug 29, 2011
- Location
- salisbury nc
I have a 1974 Chevy k20 with military dana 70 axles. I have rebuilt all the brake lines and rebuilt all the brakes and wheel cylinders. Truck has a brand new Power brake booster. I know the master cylinder and porportioning valve are both good. Heres my problem. When i bled the brakes with the truck off i get a good firm pedal and the brakes are working. If i start the truck i loose my pedal but the brakes still work once the pedal is to the floor. I have tried bleeding them while the truck is running and nothing i do stiffens the pedal back up. I know i'm getting good vacum from the manifold. If anyone has any suggestions or sees anything i'm missing or not doing please let me know. At a stand still on this build until i can figure this out.